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* [PATCH] net: check for dev pointer being NULL in dev_hard_header() to avoid GPF
@ 2022-11-30 14:11 George Kennedy
  2022-12-01 13:16 ` Pavan Chebbi
  0 siblings, 1 reply; 8+ messages in thread
From: George Kennedy @ 2022-11-30 14:11 UTC (permalink / raw)
  To: davem, edumazet, kuba, pabeni
  Cc: george.kennedy, netdev, linux-kernel, bpf, harshit.m.mogalapalli

The dev pointer can be NULL in dev_hard_header(). Add check for dev being
NULL in dev_hard_header() to avoid GPF.

general protection fault, probably for non-canonical address
    0xdffffc0000000046: 0000 [#1] PREEMPT SMP KASAN NOPTI
KASAN: null-ptr-deref in range [0x0000000000000230-0x0000000000000237]
CPU: 1 PID: 45 Comm: kworker/1:1 Not tainted 6.1.0-rc7+ #2
Hardware name: Red Hat KVM, BIOS 1.15.0-2.module+el8.6.0+20659+3dcf7c70
Workqueue: mld mld_ifc_work
RIP: 0010:macvlan_hard_header (./include/linux/netdevice.h:3057
    (discriminator 4) drivers/net/macvlan.c:594 (discriminator 4))
RSP: 0018:ffff888103d377d0 EFLAGS: 00010212
RAX: dffffc0000000000 RBX: ffff88801cf1a000 RCX: 0000000000000000
RDX: 0000000000000046 RSI: 0000000000000000 RDI: 0000000000000230
RBP: ffff88801e8ef328 R08: 0000000000000000 R09: 0000000000000060
R10: 0000000000000000 R11: 0000000000000000 R12: ffff88801f0497c0
R13: 0000000000000000 R14: ffff888045187c98 R15: 0000000000000060
FS:  0000000000000000(0000) GS:ffff888106c80000(0000)
    knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007fbf3f1c1840 CR3: 0000000014e36000 CR4: 00000000000006e0
Call Trace:
 <TASK>
neigh_connected_output (./include/linux/netdevice.h:3060
    net/core/neighbour.c:1595)
ip6_finish_output2 (./include/net/neighbour.h:546
    net/ipv6/ip6_output.c:134)
ip6_finish_output (net/ipv6/ip6_output.c:195 net/ipv6/ip6_output.c:206)
ip6_output (./include/linux/netfilter.h:291 net/ipv6/ip6_output.c:227)
NF_HOOK.constprop.0 (./include/net/dst.h:445
    ./include/linux/netfilter.h:302)
mld_sendpack (net/ipv6/mcast.c:1824)
mld_send_cr (net/ipv6/mcast.c:2122)
mld_ifc_work (net/ipv6/mcast.c:2655)
process_one_work (kernel/workqueue.c:2294)
worker_thread (./include/linux/list.h:292 kernel/workqueue.c:2437)
kthread (kernel/kthread.c:376)
ret_from_fork (arch/x86/entry/entry_64.S:312)
 </TASK>
Modules linked in:
Dumping ftrace buffer:
   (ftrace buffer empty)
---[ end trace 0000000000000000 ]---

Fixes: 0c4e85813d0a ("[NET]: Wrap netdevice hardware header creation.")
Reported-by: syzkaller <syzkaller@googlegroups.com>
Signed-off-by: George Kennedy <george.kennedy@oracle.com>
---
 include/linux/netdevice.h | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/include/linux/netdevice.h b/include/linux/netdevice.h
index eddf8ee270e7..9b25a6301fa5 100644
--- a/include/linux/netdevice.h
+++ b/include/linux/netdevice.h
@@ -3054,7 +3054,7 @@ static inline int dev_hard_header(struct sk_buff *skb, struct net_device *dev,
 				  const void *daddr, const void *saddr,
 				  unsigned int len)
 {
-	if (!dev->header_ops || !dev->header_ops->create)
+	if (!dev || !dev->header_ops || !dev->header_ops->create)
 		return 0;
 
 	return dev->header_ops->create(skb, dev, type, daddr, saddr, len);
-- 
2.31.1


^ permalink raw reply related	[flat|nested] 8+ messages in thread

* Re: [PATCH] net: check for dev pointer being NULL in dev_hard_header() to avoid GPF
  2022-11-30 14:11 [PATCH] net: check for dev pointer being NULL in dev_hard_header() to avoid GPF George Kennedy
@ 2022-12-01 13:16 ` Pavan Chebbi
  2022-12-01 19:25   ` Eric Dumazet
  0 siblings, 1 reply; 8+ messages in thread
From: Pavan Chebbi @ 2022-12-01 13:16 UTC (permalink / raw)
  To: George Kennedy
  Cc: davem, edumazet, kuba, pabeni, netdev, linux-kernel, bpf,
	harshit.m.mogalapalli

[-- Attachment #1: Type: text/plain, Size: 3274 bytes --]

On Wed, Nov 30, 2022 at 7:43 PM George Kennedy
<george.kennedy@oracle.com> wrote:
>
> The dev pointer can be NULL in dev_hard_header(). Add check for dev being
> NULL in dev_hard_header() to avoid GPF.
>
> general protection fault, probably for non-canonical address
>     0xdffffc0000000046: 0000 [#1] PREEMPT SMP KASAN NOPTI
> KASAN: null-ptr-deref in range [0x0000000000000230-0x0000000000000237]
> CPU: 1 PID: 45 Comm: kworker/1:1 Not tainted 6.1.0-rc7+ #2
> Hardware name: Red Hat KVM, BIOS 1.15.0-2.module+el8.6.0+20659+3dcf7c70
> Workqueue: mld mld_ifc_work
> RIP: 0010:macvlan_hard_header (./include/linux/netdevice.h:3057
>     (discriminator 4) drivers/net/macvlan.c:594 (discriminator 4))
> RSP: 0018:ffff888103d377d0 EFLAGS: 00010212
> RAX: dffffc0000000000 RBX: ffff88801cf1a000 RCX: 0000000000000000
> RDX: 0000000000000046 RSI: 0000000000000000 RDI: 0000000000000230
> RBP: ffff88801e8ef328 R08: 0000000000000000 R09: 0000000000000060
> R10: 0000000000000000 R11: 0000000000000000 R12: ffff88801f0497c0
> R13: 0000000000000000 R14: ffff888045187c98 R15: 0000000000000060
> FS:  0000000000000000(0000) GS:ffff888106c80000(0000)
>     knlGS:0000000000000000
> CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
> CR2: 00007fbf3f1c1840 CR3: 0000000014e36000 CR4: 00000000000006e0
> Call Trace:
>  <TASK>
> neigh_connected_output (./include/linux/netdevice.h:3060
>     net/core/neighbour.c:1595)
> ip6_finish_output2 (./include/net/neighbour.h:546
>     net/ipv6/ip6_output.c:134)
> ip6_finish_output (net/ipv6/ip6_output.c:195 net/ipv6/ip6_output.c:206)
> ip6_output (./include/linux/netfilter.h:291 net/ipv6/ip6_output.c:227)
> NF_HOOK.constprop.0 (./include/net/dst.h:445
>     ./include/linux/netfilter.h:302)
> mld_sendpack (net/ipv6/mcast.c:1824)
> mld_send_cr (net/ipv6/mcast.c:2122)
> mld_ifc_work (net/ipv6/mcast.c:2655)
> process_one_work (kernel/workqueue.c:2294)
> worker_thread (./include/linux/list.h:292 kernel/workqueue.c:2437)
> kthread (kernel/kthread.c:376)
> ret_from_fork (arch/x86/entry/entry_64.S:312)
>  </TASK>
> Modules linked in:
> Dumping ftrace buffer:
>    (ftrace buffer empty)
> ---[ end trace 0000000000000000 ]---
>
> Fixes: 0c4e85813d0a ("[NET]: Wrap netdevice hardware header creation.")
> Reported-by: syzkaller <syzkaller@googlegroups.com>
> Signed-off-by: George Kennedy <george.kennedy@oracle.com>
> ---
>  include/linux/netdevice.h | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/include/linux/netdevice.h b/include/linux/netdevice.h
> index eddf8ee270e7..9b25a6301fa5 100644
> --- a/include/linux/netdevice.h
> +++ b/include/linux/netdevice.h
> @@ -3054,7 +3054,7 @@ static inline int dev_hard_header(struct sk_buff *skb, struct net_device *dev,
>                                   const void *daddr, const void *saddr,
>                                   unsigned int len)
>  {
> -       if (!dev->header_ops || !dev->header_ops->create)
> +       if (!dev || !dev->header_ops || !dev->header_ops->create)
>                 return 0;

net_device being NULL during eth header construction? seems like a
more serious issue?
If it indeed is a genuine scenario I think a better description is needed...

>
>         return dev->header_ops->create(skb, dev, type, daddr, saddr, len);
> --
> 2.31.1
>

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^ permalink raw reply	[flat|nested] 8+ messages in thread

* Re: [PATCH] net: check for dev pointer being NULL in dev_hard_header() to avoid GPF
  2022-12-01 13:16 ` Pavan Chebbi
@ 2022-12-01 19:25   ` Eric Dumazet
  2022-12-01 20:10     ` George Kennedy
  0 siblings, 1 reply; 8+ messages in thread
From: Eric Dumazet @ 2022-12-01 19:25 UTC (permalink / raw)
  To: Pavan Chebbi
  Cc: George Kennedy, davem, kuba, pabeni, netdev, linux-kernel, bpf,
	harshit.m.mogalapalli

On Thu, Dec 1, 2022 at 2:16 PM Pavan Chebbi <pavan.chebbi@broadcom.com> wrote:
>
> On Wed, Nov 30, 2022 at 7:43 PM George Kennedy
> <george.kennedy@oracle.com> wrote:
> >
> > The dev pointer can be NULL in dev_hard_header(). Add check for dev being
> > NULL in dev_hard_header() to avoid GPF.
> >
> > general protection fault, probably for non-canonical address
> >     0xdffffc0000000046: 0000 [#1] PREEMPT SMP KASAN NOPTI
> > KASAN: null-ptr-deref in range [0x0000000000000230-0x0000000000000237]
> > CPU: 1 PID: 45 Comm: kworker/1:1 Not tainted 6.1.0-rc7+ #2
> > Hardware name: Red Hat KVM, BIOS 1.15.0-2.module+el8.6.0+20659+3dcf7c70
> > Workqueue: mld mld_ifc_work
> > RIP: 0010:macvlan_hard_header (./include/linux/netdevice.h:3057
> >     (discriminator 4) drivers/net/macvlan.c:594 (discriminator 4))
> > RSP: 0018:ffff888103d377d0 EFLAGS: 00010212
> > RAX: dffffc0000000000 RBX: ffff88801cf1a000 RCX: 0000000000000000
> > RDX: 0000000000000046 RSI: 0000000000000000 RDI: 0000000000000230
> > RBP: ffff88801e8ef328 R08: 0000000000000000 R09: 0000000000000060
> > R10: 0000000000000000 R11: 0000000000000000 R12: ffff88801f0497c0
> > R13: 0000000000000000 R14: ffff888045187c98 R15: 0000000000000060
> > FS:  0000000000000000(0000) GS:ffff888106c80000(0000)
> >     knlGS:0000000000000000
> > CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
> > CR2: 00007fbf3f1c1840 CR3: 0000000014e36000 CR4: 00000000000006e0
> > Call Trace:
> >  <TASK>
> > neigh_connected_output (./include/linux/netdevice.h:3060
> >     net/core/neighbour.c:1595)
> > ip6_finish_output2 (./include/net/neighbour.h:546
> >     net/ipv6/ip6_output.c:134)
> > ip6_finish_output (net/ipv6/ip6_output.c:195 net/ipv6/ip6_output.c:206)
> > ip6_output (./include/linux/netfilter.h:291 net/ipv6/ip6_output.c:227)
> > NF_HOOK.constprop.0 (./include/net/dst.h:445
> >     ./include/linux/netfilter.h:302)
> > mld_sendpack (net/ipv6/mcast.c:1824)
> > mld_send_cr (net/ipv6/mcast.c:2122)
> > mld_ifc_work (net/ipv6/mcast.c:2655)
> > process_one_work (kernel/workqueue.c:2294)
> > worker_thread (./include/linux/list.h:292 kernel/workqueue.c:2437)
> > kthread (kernel/kthread.c:376)
> > ret_from_fork (arch/x86/entry/entry_64.S:312)
> >  </TASK>
> > Modules linked in:
> > Dumping ftrace buffer:
> >    (ftrace buffer empty)
> > ---[ end trace 0000000000000000 ]---
> >
> > Fixes: 0c4e85813d0a ("[NET]: Wrap netdevice hardware header creation.")
> > Reported-by: syzkaller <syzkaller@googlegroups.com>
> > Signed-off-by: George Kennedy <george.kennedy@oracle.com>
> > ---
> >  include/linux/netdevice.h | 2 +-
> >  1 file changed, 1 insertion(+), 1 deletion(-)
> >
> > diff --git a/include/linux/netdevice.h b/include/linux/netdevice.h
> > index eddf8ee270e7..9b25a6301fa5 100644
> > --- a/include/linux/netdevice.h
> > +++ b/include/linux/netdevice.h
> > @@ -3054,7 +3054,7 @@ static inline int dev_hard_header(struct sk_buff *skb, struct net_device *dev,
> >                                   const void *daddr, const void *saddr,
> >                                   unsigned int len)
> >  {
> > -       if (!dev->header_ops || !dev->header_ops->create)
> > +       if (!dev || !dev->header_ops || !dev->header_ops->create)

Do  you have a repro ?

This patch will not prevent a crash later I think.

Please fix the root cause, thanks !

> >                 return 0;
>
> net_device being NULL during eth header construction? seems like a
> more serious issue?
> If it indeed is a genuine scenario I think a better description is needed...
>
> >
> >         return dev->header_ops->create(skb, dev, type, daddr, saddr, len);
> > --
> > 2.31.1
> >

^ permalink raw reply	[flat|nested] 8+ messages in thread

* Re: [PATCH] net: check for dev pointer being NULL in dev_hard_header() to avoid GPF
  2022-12-01 19:25   ` Eric Dumazet
@ 2022-12-01 20:10     ` George Kennedy
  2022-12-02  4:11       ` Eric Dumazet
  0 siblings, 1 reply; 8+ messages in thread
From: George Kennedy @ 2022-12-01 20:10 UTC (permalink / raw)
  To: Eric Dumazet, Pavan Chebbi
  Cc: davem, kuba, pabeni, netdev, linux-kernel, bpf, harshit.m.mogalapalli

[-- Attachment #1: Type: text/plain, Size: 3804 bytes --]



On 12/1/2022 2:25 PM, Eric Dumazet wrote:
> On Thu, Dec 1, 2022 at 2:16 PM Pavan Chebbi <pavan.chebbi@broadcom.com> wrote:
>> On Wed, Nov 30, 2022 at 7:43 PM George Kennedy
>> <george.kennedy@oracle.com> wrote:
>>> The dev pointer can be NULL in dev_hard_header(). Add check for dev being
>>> NULL in dev_hard_header() to avoid GPF.
>>>
>>> general protection fault, probably for non-canonical address
>>>      0xdffffc0000000046: 0000 [#1] PREEMPT SMP KASAN NOPTI
>>> KASAN: null-ptr-deref in range [0x0000000000000230-0x0000000000000237]
>>> CPU: 1 PID: 45 Comm: kworker/1:1 Not tainted 6.1.0-rc7+ #2
>>> Hardware name: Red Hat KVM, BIOS 1.15.0-2.module+el8.6.0+20659+3dcf7c70
>>> Workqueue: mld mld_ifc_work
>>> RIP: 0010:macvlan_hard_header (./include/linux/netdevice.h:3057
>>>      (discriminator 4) drivers/net/macvlan.c:594 (discriminator 4))
>>> RSP: 0018:ffff888103d377d0 EFLAGS: 00010212
>>> RAX: dffffc0000000000 RBX: ffff88801cf1a000 RCX: 0000000000000000
>>> RDX: 0000000000000046 RSI: 0000000000000000 RDI: 0000000000000230
>>> RBP: ffff88801e8ef328 R08: 0000000000000000 R09: 0000000000000060
>>> R10: 0000000000000000 R11: 0000000000000000 R12: ffff88801f0497c0
>>> R13: 0000000000000000 R14: ffff888045187c98 R15: 0000000000000060
>>> FS:  0000000000000000(0000) GS:ffff888106c80000(0000)
>>>      knlGS:0000000000000000
>>> CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
>>> CR2: 00007fbf3f1c1840 CR3: 0000000014e36000 CR4: 00000000000006e0
>>> Call Trace:
>>>   <TASK>
>>> neigh_connected_output (./include/linux/netdevice.h:3060
>>>      net/core/neighbour.c:1595)
>>> ip6_finish_output2 (./include/net/neighbour.h:546
>>>      net/ipv6/ip6_output.c:134)
>>> ip6_finish_output (net/ipv6/ip6_output.c:195 net/ipv6/ip6_output.c:206)
>>> ip6_output (./include/linux/netfilter.h:291 net/ipv6/ip6_output.c:227)
>>> NF_HOOK.constprop.0 (./include/net/dst.h:445
>>>      ./include/linux/netfilter.h:302)
>>> mld_sendpack (net/ipv6/mcast.c:1824)
>>> mld_send_cr (net/ipv6/mcast.c:2122)
>>> mld_ifc_work (net/ipv6/mcast.c:2655)
>>> process_one_work (kernel/workqueue.c:2294)
>>> worker_thread (./include/linux/list.h:292 kernel/workqueue.c:2437)
>>> kthread (kernel/kthread.c:376)
>>> ret_from_fork (arch/x86/entry/entry_64.S:312)
>>>   </TASK>
>>> Modules linked in:
>>> Dumping ftrace buffer:
>>>     (ftrace buffer empty)
>>> ---[ end trace 0000000000000000 ]---
>>>
>>> Fixes: 0c4e85813d0a ("[NET]: Wrap netdevice hardware header creation.")
>>> Reported-by: syzkaller <syzkaller@googlegroups.com>
>>> Signed-off-by: George Kennedy <george.kennedy@oracle.com>
>>> ---
>>>   include/linux/netdevice.h | 2 +-
>>>   1 file changed, 1 insertion(+), 1 deletion(-)
>>>
>>> diff --git a/include/linux/netdevice.h b/include/linux/netdevice.h
>>> index eddf8ee270e7..9b25a6301fa5 100644
>>> --- a/include/linux/netdevice.h
>>> +++ b/include/linux/netdevice.h
>>> @@ -3054,7 +3054,7 @@ static inline int dev_hard_header(struct sk_buff *skb, struct net_device *dev,
>>>                                    const void *daddr, const void *saddr,
>>>                                    unsigned int len)
>>>   {
>>> -       if (!dev->header_ops || !dev->header_ops->create)
>>> +       if (!dev || !dev->header_ops || !dev->header_ops->create)
> Do  you have a repro ?
See syzkaller repros attached.

> This patch will not prevent a crash later I think.

The repro ran overnight without failure with the patch applied.

>
> Please fix the root cause, thanks !

Will try.

Thanks,
George
>
>>>                  return 0;
>> net_device being NULL during eth header construction? seems like a
>> more serious issue?
>> If it indeed is a genuine scenario I think a better description is needed...
>>
>>>          return dev->header_ops->create(skb, dev, type, daddr, saddr, len);
>>> --
>>> 2.31.1
>>>

[-- Attachment #2: repro_macvlan1.c --]
[-- Type: text/plain, Size: 44989 bytes --]

// general protection fault in macvlan_hard_header
// https://syzkaller.appspot.com/bug?id=3c51126024b6157a3f7ac2a11317f4a056d33f24
// status:open
// autogenerated by syzkaller (https://github.com/google/syzkaller)

#define _GNU_SOURCE

#include <arpa/inet.h>
#include <dirent.h>
#include <endian.h>
#include <errno.h>
#include <fcntl.h>
#include <net/if.h>
#include <net/if_arp.h>
#include <netinet/in.h>
#include <sched.h>
#include <signal.h>
#include <stdarg.h>
#include <stdbool.h>
#include <stdint.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <sys/ioctl.h>
#include <sys/mount.h>
#include <sys/prctl.h>
#include <sys/resource.h>
#include <sys/socket.h>
#include <sys/stat.h>
#include <sys/syscall.h>
#include <sys/time.h>
#include <sys/types.h>
#include <sys/uio.h>
#include <sys/wait.h>
#include <time.h>
#include <unistd.h>

#include <linux/capability.h>
#include <linux/genetlink.h>
#include <linux/if_addr.h>
#include <linux/if_ether.h>
#include <linux/if_link.h>
#include <linux/if_tun.h>
#include <linux/in6.h>
#include <linux/ip.h>
#include <linux/neighbour.h>
#include <linux/net.h>
#include <linux/netlink.h>
#include <linux/rtnetlink.h>
#include <linux/tcp.h>
#include <linux/veth.h>

unsigned long long procid;

static void sleep_ms(uint64_t ms)
{
  usleep(ms * 1000);
}

static uint64_t current_time_ms(void)
{
  struct timespec ts;
  if (clock_gettime(CLOCK_MONOTONIC, &ts))
    exit(1);
  return (uint64_t)ts.tv_sec * 1000 + (uint64_t)ts.tv_nsec / 1000000;
}

#define BITMASK(bf_off, bf_len) (((1ull << (bf_len)) - 1) << (bf_off))
#define STORE_BY_BITMASK(type, htobe, addr, val, bf_off, bf_len)               \
  *(type*)(addr) =                                                             \
      htobe((htobe(*(type*)(addr)) & ~BITMASK((bf_off), (bf_len))) |           \
            (((type)(val) << (bf_off)) & BITMASK((bf_off), (bf_len))))

static bool write_file(const char* file, const char* what, ...)
{
  char buf[1024];
  va_list args;
  va_start(args, what);
  vsnprintf(buf, sizeof(buf), what, args);
  va_end(args);
  buf[sizeof(buf) - 1] = 0;
  int len = strlen(buf);
  int fd = open(file, O_WRONLY | O_CLOEXEC);
  if (fd == -1)
    return false;
  if (write(fd, buf, len) != len) {
    int err = errno;
    close(fd);
    errno = err;
    return false;
  }
  close(fd);
  return true;
}

struct nlmsg {
  char* pos;
  int nesting;
  struct nlattr* nested[8];
  char buf[1024];
};

static struct nlmsg nlmsg;

static void netlink_init(struct nlmsg* nlmsg, int typ, int flags,
                         const void* data, int size)
{
  memset(nlmsg, 0, sizeof(*nlmsg));
  struct nlmsghdr* hdr = (struct nlmsghdr*)nlmsg->buf;
  hdr->nlmsg_type = typ;
  hdr->nlmsg_flags = NLM_F_REQUEST | NLM_F_ACK | flags;
  memcpy(hdr + 1, data, size);
  nlmsg->pos = (char*)(hdr + 1) + NLMSG_ALIGN(size);
}

static void netlink_attr(struct nlmsg* nlmsg, int typ, const void* data,
                         int size)
{
  struct nlattr* attr = (struct nlattr*)nlmsg->pos;
  attr->nla_len = sizeof(*attr) + size;
  attr->nla_type = typ;
  memcpy(attr + 1, data, size);
  nlmsg->pos += NLMSG_ALIGN(attr->nla_len);
}

static void netlink_nest(struct nlmsg* nlmsg, int typ)
{
  struct nlattr* attr = (struct nlattr*)nlmsg->pos;
  attr->nla_type = typ;
  nlmsg->pos += sizeof(*attr);
  nlmsg->nested[nlmsg->nesting++] = attr;
}

static void netlink_done(struct nlmsg* nlmsg)
{
  struct nlattr* attr = nlmsg->nested[--nlmsg->nesting];
  attr->nla_len = nlmsg->pos - (char*)attr;
}

static int netlink_send_ext(struct nlmsg* nlmsg, int sock, uint16_t reply_type,
                            int* reply_len)
{
  if (nlmsg->pos > nlmsg->buf + sizeof(nlmsg->buf) || nlmsg->nesting)
    exit(1);
  struct nlmsghdr* hdr = (struct nlmsghdr*)nlmsg->buf;
  hdr->nlmsg_len = nlmsg->pos - nlmsg->buf;
  struct sockaddr_nl addr;
  memset(&addr, 0, sizeof(addr));
  addr.nl_family = AF_NETLINK;
  unsigned n = sendto(sock, nlmsg->buf, hdr->nlmsg_len, 0,
                      (struct sockaddr*)&addr, sizeof(addr));
  if (n != hdr->nlmsg_len)
    exit(1);
  n = recv(sock, nlmsg->buf, sizeof(nlmsg->buf), 0);
  if (hdr->nlmsg_type == NLMSG_DONE) {
    *reply_len = 0;
    return 0;
  }
  if (n < sizeof(struct nlmsghdr))
    exit(1);
  if (reply_len && hdr->nlmsg_type == reply_type) {
    *reply_len = n;
    return 0;
  }
  if (n < sizeof(struct nlmsghdr) + sizeof(struct nlmsgerr))
    exit(1);
  if (hdr->nlmsg_type != NLMSG_ERROR)
    exit(1);
  return -((struct nlmsgerr*)(hdr + 1))->error;
}

static int netlink_send(struct nlmsg* nlmsg, int sock)
{
  return netlink_send_ext(nlmsg, sock, 0, NULL);
}

static int netlink_next_msg(struct nlmsg* nlmsg, unsigned int offset,
                            unsigned int total_len)
{
  struct nlmsghdr* hdr = (struct nlmsghdr*)(nlmsg->buf + offset);
  if (offset == total_len || offset + hdr->nlmsg_len > total_len)
    return -1;
  return hdr->nlmsg_len;
}

static void netlink_add_device_impl(struct nlmsg* nlmsg, const char* type,
                                    const char* name)
{
  struct ifinfomsg hdr;
  memset(&hdr, 0, sizeof(hdr));
  netlink_init(nlmsg, RTM_NEWLINK, NLM_F_EXCL | NLM_F_CREATE, &hdr,
               sizeof(hdr));
  if (name)
    netlink_attr(nlmsg, IFLA_IFNAME, name, strlen(name));
  netlink_nest(nlmsg, IFLA_LINKINFO);
  netlink_attr(nlmsg, IFLA_INFO_KIND, type, strlen(type));
}

static void netlink_add_device(struct nlmsg* nlmsg, int sock, const char* type,
                               const char* name)
{
  netlink_add_device_impl(nlmsg, type, name);
  netlink_done(nlmsg);
  int err = netlink_send(nlmsg, sock);
  (void)err;
}

static void netlink_add_veth(struct nlmsg* nlmsg, int sock, const char* name,
                             const char* peer)
{
  netlink_add_device_impl(nlmsg, "veth", name);
  netlink_nest(nlmsg, IFLA_INFO_DATA);
  netlink_nest(nlmsg, VETH_INFO_PEER);
  nlmsg->pos += sizeof(struct ifinfomsg);
  netlink_attr(nlmsg, IFLA_IFNAME, peer, strlen(peer));
  netlink_done(nlmsg);
  netlink_done(nlmsg);
  netlink_done(nlmsg);
  int err = netlink_send(nlmsg, sock);
  (void)err;
}

static void netlink_add_hsr(struct nlmsg* nlmsg, int sock, const char* name,
                            const char* slave1, const char* slave2)
{
  netlink_add_device_impl(nlmsg, "hsr", name);
  netlink_nest(nlmsg, IFLA_INFO_DATA);
  int ifindex1 = if_nametoindex(slave1);
  netlink_attr(nlmsg, IFLA_HSR_SLAVE1, &ifindex1, sizeof(ifindex1));
  int ifindex2 = if_nametoindex(slave2);
  netlink_attr(nlmsg, IFLA_HSR_SLAVE2, &ifindex2, sizeof(ifindex2));
  netlink_done(nlmsg);
  netlink_done(nlmsg);
  int err = netlink_send(nlmsg, sock);
  (void)err;
}

static void netlink_add_linked(struct nlmsg* nlmsg, int sock, const char* type,
                               const char* name, const char* link)
{
  netlink_add_device_impl(nlmsg, type, name);
  netlink_done(nlmsg);
  int ifindex = if_nametoindex(link);
  netlink_attr(nlmsg, IFLA_LINK, &ifindex, sizeof(ifindex));
  int err = netlink_send(nlmsg, sock);
  (void)err;
}

static void netlink_add_vlan(struct nlmsg* nlmsg, int sock, const char* name,
                             const char* link, uint16_t id, uint16_t proto)
{
  netlink_add_device_impl(nlmsg, "vlan", name);
  netlink_nest(nlmsg, IFLA_INFO_DATA);
  netlink_attr(nlmsg, IFLA_VLAN_ID, &id, sizeof(id));
  netlink_attr(nlmsg, IFLA_VLAN_PROTOCOL, &proto, sizeof(proto));
  netlink_done(nlmsg);
  netlink_done(nlmsg);
  int ifindex = if_nametoindex(link);
  netlink_attr(nlmsg, IFLA_LINK, &ifindex, sizeof(ifindex));
  int err = netlink_send(nlmsg, sock);
  (void)err;
}

static void netlink_add_macvlan(struct nlmsg* nlmsg, int sock, const char* name,
                                const char* link)
{
  netlink_add_device_impl(nlmsg, "macvlan", name);
  netlink_nest(nlmsg, IFLA_INFO_DATA);
  uint32_t mode = MACVLAN_MODE_BRIDGE;
  netlink_attr(nlmsg, IFLA_MACVLAN_MODE, &mode, sizeof(mode));
  netlink_done(nlmsg);
  netlink_done(nlmsg);
  int ifindex = if_nametoindex(link);
  netlink_attr(nlmsg, IFLA_LINK, &ifindex, sizeof(ifindex));
  int err = netlink_send(nlmsg, sock);
  (void)err;
}

static void netlink_add_geneve(struct nlmsg* nlmsg, int sock, const char* name,
                               uint32_t vni, struct in_addr* addr4,
                               struct in6_addr* addr6)
{
  netlink_add_device_impl(nlmsg, "geneve", name);
  netlink_nest(nlmsg, IFLA_INFO_DATA);
  netlink_attr(nlmsg, IFLA_GENEVE_ID, &vni, sizeof(vni));
  if (addr4)
    netlink_attr(nlmsg, IFLA_GENEVE_REMOTE, addr4, sizeof(*addr4));
  if (addr6)
    netlink_attr(nlmsg, IFLA_GENEVE_REMOTE6, addr6, sizeof(*addr6));
  netlink_done(nlmsg);
  netlink_done(nlmsg);
  int err = netlink_send(nlmsg, sock);
  (void)err;
}

#define IFLA_IPVLAN_FLAGS 2
#define IPVLAN_MODE_L3S 2
#undef IPVLAN_F_VEPA
#define IPVLAN_F_VEPA 2

static void netlink_add_ipvlan(struct nlmsg* nlmsg, int sock, const char* name,
                               const char* link, uint16_t mode, uint16_t flags)
{
  netlink_add_device_impl(nlmsg, "ipvlan", name);
  netlink_nest(nlmsg, IFLA_INFO_DATA);
  netlink_attr(nlmsg, IFLA_IPVLAN_MODE, &mode, sizeof(mode));
  netlink_attr(nlmsg, IFLA_IPVLAN_FLAGS, &flags, sizeof(flags));
  netlink_done(nlmsg);
  netlink_done(nlmsg);
  int ifindex = if_nametoindex(link);
  netlink_attr(nlmsg, IFLA_LINK, &ifindex, sizeof(ifindex));
  int err = netlink_send(nlmsg, sock);
  (void)err;
}

static void netlink_device_change(struct nlmsg* nlmsg, int sock,
                                  const char* name, bool up, const char* master,
                                  const void* mac, int macsize,
                                  const char* new_name)
{
  struct ifinfomsg hdr;
  memset(&hdr, 0, sizeof(hdr));
  if (up)
    hdr.ifi_flags = hdr.ifi_change = IFF_UP;
  hdr.ifi_index = if_nametoindex(name);
  netlink_init(nlmsg, RTM_NEWLINK, 0, &hdr, sizeof(hdr));
  if (new_name)
    netlink_attr(nlmsg, IFLA_IFNAME, new_name, strlen(new_name));
  if (master) {
    int ifindex = if_nametoindex(master);
    netlink_attr(nlmsg, IFLA_MASTER, &ifindex, sizeof(ifindex));
  }
  if (macsize)
    netlink_attr(nlmsg, IFLA_ADDRESS, mac, macsize);
  int err = netlink_send(nlmsg, sock);
  (void)err;
}

static int netlink_add_addr(struct nlmsg* nlmsg, int sock, const char* dev,
                            const void* addr, int addrsize)
{
  struct ifaddrmsg hdr;
  memset(&hdr, 0, sizeof(hdr));
  hdr.ifa_family = addrsize == 4 ? AF_INET : AF_INET6;
  hdr.ifa_prefixlen = addrsize == 4 ? 24 : 120;
  hdr.ifa_scope = RT_SCOPE_UNIVERSE;
  hdr.ifa_index = if_nametoindex(dev);
  netlink_init(nlmsg, RTM_NEWADDR, NLM_F_CREATE | NLM_F_REPLACE, &hdr,
               sizeof(hdr));
  netlink_attr(nlmsg, IFA_LOCAL, addr, addrsize);
  netlink_attr(nlmsg, IFA_ADDRESS, addr, addrsize);
  return netlink_send(nlmsg, sock);
}

static void netlink_add_addr4(struct nlmsg* nlmsg, int sock, const char* dev,
                              const char* addr)
{
  struct in_addr in_addr;
  inet_pton(AF_INET, addr, &in_addr);
  int err = netlink_add_addr(nlmsg, sock, dev, &in_addr, sizeof(in_addr));
  (void)err;
}

static void netlink_add_addr6(struct nlmsg* nlmsg, int sock, const char* dev,
                              const char* addr)
{
  struct in6_addr in6_addr;
  inet_pton(AF_INET6, addr, &in6_addr);
  int err = netlink_add_addr(nlmsg, sock, dev, &in6_addr, sizeof(in6_addr));
  (void)err;
}

static void netlink_add_neigh(struct nlmsg* nlmsg, int sock, const char* name,
                              const void* addr, int addrsize, const void* mac,
                              int macsize)
{
  struct ndmsg hdr;
  memset(&hdr, 0, sizeof(hdr));
  hdr.ndm_family = addrsize == 4 ? AF_INET : AF_INET6;
  hdr.ndm_ifindex = if_nametoindex(name);
  hdr.ndm_state = NUD_PERMANENT;
  netlink_init(nlmsg, RTM_NEWNEIGH, NLM_F_EXCL | NLM_F_CREATE, &hdr,
               sizeof(hdr));
  netlink_attr(nlmsg, NDA_DST, addr, addrsize);
  netlink_attr(nlmsg, NDA_LLADDR, mac, macsize);
  int err = netlink_send(nlmsg, sock);
  (void)err;
}

static int tunfd = -1;
static int tun_frags_enabled;

#define TUN_IFACE "syz_tun"

#define LOCAL_MAC 0xaaaaaaaaaaaa
#define REMOTE_MAC 0xaaaaaaaaaabb

#define LOCAL_IPV4 "172.20.20.170"
#define REMOTE_IPV4 "172.20.20.187"

#define LOCAL_IPV6 "fe80::aa"
#define REMOTE_IPV6 "fe80::bb"

#define IFF_NAPI 0x0010
#define IFF_NAPI_FRAGS 0x0020

static void initialize_tun(void)
{
  tunfd = open("/dev/net/tun", O_RDWR | O_NONBLOCK);
  if (tunfd == -1) {
    printf("tun: can't open /dev/net/tun: please enable CONFIG_TUN=y\n");
    printf("otherwise fuzzing or reproducing might not work as intended\n");
    return;
  }
  const int kTunFd = 240;
  if (dup2(tunfd, kTunFd) < 0)
    exit(1);
  close(tunfd);
  tunfd = kTunFd;
  struct ifreq ifr;
  memset(&ifr, 0, sizeof(ifr));
  strncpy(ifr.ifr_name, TUN_IFACE, IFNAMSIZ);
  ifr.ifr_flags = IFF_TAP | IFF_NO_PI;
  if (ioctl(tunfd, TUNSETIFF, (void*)&ifr) < 0) {
    exit(1);
  }
  char sysctl[64];
  sprintf(sysctl, "/proc/sys/net/ipv6/conf/%s/accept_dad", TUN_IFACE);
  write_file(sysctl, "0");
  sprintf(sysctl, "/proc/sys/net/ipv6/conf/%s/router_solicitations", TUN_IFACE);
  write_file(sysctl, "0");
  int sock = socket(AF_NETLINK, SOCK_RAW, NETLINK_ROUTE);
  if (sock == -1)
    exit(1);
  netlink_add_addr4(&nlmsg, sock, TUN_IFACE, LOCAL_IPV4);
  netlink_add_addr6(&nlmsg, sock, TUN_IFACE, LOCAL_IPV6);
  uint64_t macaddr = REMOTE_MAC;
  struct in_addr in_addr;
  inet_pton(AF_INET, REMOTE_IPV4, &in_addr);
  netlink_add_neigh(&nlmsg, sock, TUN_IFACE, &in_addr, sizeof(in_addr),
                    &macaddr, ETH_ALEN);
  struct in6_addr in6_addr;
  inet_pton(AF_INET6, REMOTE_IPV6, &in6_addr);
  netlink_add_neigh(&nlmsg, sock, TUN_IFACE, &in6_addr, sizeof(in6_addr),
                    &macaddr, ETH_ALEN);
  macaddr = LOCAL_MAC;
  netlink_device_change(&nlmsg, sock, TUN_IFACE, true, 0, &macaddr, ETH_ALEN,
                        NULL);
  close(sock);
}

#define DEVLINK_FAMILY_NAME "devlink"

#define DEVLINK_CMD_PORT_GET 5
#define DEVLINK_ATTR_BUS_NAME 1
#define DEVLINK_ATTR_DEV_NAME 2
#define DEVLINK_ATTR_NETDEV_NAME 7

static int netlink_devlink_id_get(struct nlmsg* nlmsg, int sock)
{
  struct genlmsghdr genlhdr;
  struct nlattr* attr;
  int err, n;
  uint16_t id = 0;
  memset(&genlhdr, 0, sizeof(genlhdr));
  genlhdr.cmd = CTRL_CMD_GETFAMILY;
  netlink_init(nlmsg, GENL_ID_CTRL, 0, &genlhdr, sizeof(genlhdr));
  netlink_attr(nlmsg, CTRL_ATTR_FAMILY_NAME, DEVLINK_FAMILY_NAME,
               strlen(DEVLINK_FAMILY_NAME) + 1);
  err = netlink_send_ext(nlmsg, sock, GENL_ID_CTRL, &n);
  if (err) {
    return -1;
  }
  attr = (struct nlattr*)(nlmsg->buf + NLMSG_HDRLEN +
                          NLMSG_ALIGN(sizeof(genlhdr)));
  for (; (char*)attr < nlmsg->buf + n;
       attr = (struct nlattr*)((char*)attr + NLMSG_ALIGN(attr->nla_len))) {
    if (attr->nla_type == CTRL_ATTR_FAMILY_ID) {
      id = *(uint16_t*)(attr + 1);
      break;
    }
  }
  if (!id) {
    return -1;
  }
  recv(sock, nlmsg->buf, sizeof(nlmsg->buf), 0); /* recv ack */
  return id;
}

static struct nlmsg nlmsg2;

static void initialize_devlink_ports(const char* bus_name, const char* dev_name,
                                     const char* netdev_prefix)
{
  struct genlmsghdr genlhdr;
  int len, total_len, id, err, offset;
  uint16_t netdev_index;
  int sock = socket(AF_NETLINK, SOCK_RAW, NETLINK_GENERIC);
  if (sock == -1)
    exit(1);
  int rtsock = socket(AF_NETLINK, SOCK_RAW, NETLINK_ROUTE);
  if (rtsock == -1)
    exit(1);
  id = netlink_devlink_id_get(&nlmsg, sock);
  if (id == -1)
    goto error;
  memset(&genlhdr, 0, sizeof(genlhdr));
  genlhdr.cmd = DEVLINK_CMD_PORT_GET;
  netlink_init(&nlmsg, id, NLM_F_DUMP, &genlhdr, sizeof(genlhdr));
  netlink_attr(&nlmsg, DEVLINK_ATTR_BUS_NAME, bus_name, strlen(bus_name) + 1);
  netlink_attr(&nlmsg, DEVLINK_ATTR_DEV_NAME, dev_name, strlen(dev_name) + 1);
  err = netlink_send_ext(&nlmsg, sock, id, &total_len);
  if (err) {
    goto error;
  }
  offset = 0;
  netdev_index = 0;
  while ((len = netlink_next_msg(&nlmsg, offset, total_len)) != -1) {
    struct nlattr* attr = (struct nlattr*)(nlmsg.buf + offset + NLMSG_HDRLEN +
                                           NLMSG_ALIGN(sizeof(genlhdr)));
    for (; (char*)attr < nlmsg.buf + offset + len;
         attr = (struct nlattr*)((char*)attr + NLMSG_ALIGN(attr->nla_len))) {
      if (attr->nla_type == DEVLINK_ATTR_NETDEV_NAME) {
        char* port_name;
        char netdev_name[IFNAMSIZ];
        port_name = (char*)(attr + 1);
        snprintf(netdev_name, sizeof(netdev_name), "%s%d", netdev_prefix,
                 netdev_index);
        netlink_device_change(&nlmsg2, rtsock, port_name, true, 0, 0, 0,
                              netdev_name);
        break;
      }
    }
    offset += len;
    netdev_index++;
  }
error:
  close(rtsock);
  close(sock);
}

#define DEV_IPV4 "172.20.20.%d"
#define DEV_IPV6 "fe80::%02x"
#define DEV_MAC 0x00aaaaaaaaaa

static void netdevsim_add(unsigned int addr, unsigned int port_count)
{
  char buf[16];
  sprintf(buf, "%u %u", addr, port_count);
  if (write_file("/sys/bus/netdevsim/new_device", buf)) {
    snprintf(buf, sizeof(buf), "netdevsim%d", addr);
    initialize_devlink_ports("netdevsim", buf, "netdevsim");
  }
}

#define WG_GENL_NAME "wireguard"
enum wg_cmd {
  WG_CMD_GET_DEVICE,
  WG_CMD_SET_DEVICE,
};
enum wgdevice_attribute {
  WGDEVICE_A_UNSPEC,
  WGDEVICE_A_IFINDEX,
  WGDEVICE_A_IFNAME,
  WGDEVICE_A_PRIVATE_KEY,
  WGDEVICE_A_PUBLIC_KEY,
  WGDEVICE_A_FLAGS,
  WGDEVICE_A_LISTEN_PORT,
  WGDEVICE_A_FWMARK,
  WGDEVICE_A_PEERS,
};
enum wgpeer_attribute {
  WGPEER_A_UNSPEC,
  WGPEER_A_PUBLIC_KEY,
  WGPEER_A_PRESHARED_KEY,
  WGPEER_A_FLAGS,
  WGPEER_A_ENDPOINT,
  WGPEER_A_PERSISTENT_KEEPALIVE_INTERVAL,
  WGPEER_A_LAST_HANDSHAKE_TIME,
  WGPEER_A_RX_BYTES,
  WGPEER_A_TX_BYTES,
  WGPEER_A_ALLOWEDIPS,
  WGPEER_A_PROTOCOL_VERSION,
};
enum wgallowedip_attribute {
  WGALLOWEDIP_A_UNSPEC,
  WGALLOWEDIP_A_FAMILY,
  WGALLOWEDIP_A_IPADDR,
  WGALLOWEDIP_A_CIDR_MASK,
};

static int netlink_wireguard_id_get(struct nlmsg* nlmsg, int sock)
{
  struct genlmsghdr genlhdr;
  struct nlattr* attr;
  int err, n;
  uint16_t id = 0;
  memset(&genlhdr, 0, sizeof(genlhdr));
  genlhdr.cmd = CTRL_CMD_GETFAMILY;
  netlink_init(nlmsg, GENL_ID_CTRL, 0, &genlhdr, sizeof(genlhdr));
  netlink_attr(nlmsg, CTRL_ATTR_FAMILY_NAME, WG_GENL_NAME,
               strlen(WG_GENL_NAME) + 1);
  err = netlink_send_ext(nlmsg, sock, GENL_ID_CTRL, &n);
  if (err) {
    return -1;
  }
  attr = (struct nlattr*)(nlmsg->buf + NLMSG_HDRLEN +
                          NLMSG_ALIGN(sizeof(genlhdr)));
  for (; (char*)attr < nlmsg->buf + n;
       attr = (struct nlattr*)((char*)attr + NLMSG_ALIGN(attr->nla_len))) {
    if (attr->nla_type == CTRL_ATTR_FAMILY_ID) {
      id = *(uint16_t*)(attr + 1);
      break;
    }
  }
  if (!id) {
    return -1;
  }
  recv(sock, nlmsg->buf, sizeof(nlmsg->buf), 0); /* recv ack */
  return id;
}

static void netlink_wireguard_setup(void)
{
  const char ifname_a[] = "wg0";
  const char ifname_b[] = "wg1";
  const char ifname_c[] = "wg2";
  const char private_a[] = "\xa0\x5c\xa8\x4f\x6c\x9c\x8e\x38\x53\xe2\xfd\x7a"
                           "\x70\xae\x0f\xb2\x0f\xa1\x52\x60\x0c\xb0\x08\x45"
                           "\x17\x4f\x08\x07\x6f\x8d\x78\x43";
  const char private_b[] = "\xb0\x80\x73\xe8\xd4\x4e\x91\xe3\xda\x92\x2c\x22"
                           "\x43\x82\x44\xbb\x88\x5c\x69\xe2\x69\xc8\xe9\xd8"
                           "\x35\xb1\x14\x29\x3a\x4d\xdc\x6e";
  const char private_c[] = "\xa0\xcb\x87\x9a\x47\xf5\xbc\x64\x4c\x0e\x69\x3f"
                           "\xa6\xd0\x31\xc7\x4a\x15\x53\xb6\xe9\x01\xb9\xff"
                           "\x2f\x51\x8c\x78\x04\x2f\xb5\x42";
  const char public_a[] = "\x97\x5c\x9d\x81\xc9\x83\xc8\x20\x9e\xe7\x81\x25\x4b"
                          "\x89\x9f\x8e\xd9\x25\xae\x9f\x09\x23\xc2\x3c\x62\xf5"
                          "\x3c\x57\xcd\xbf\x69\x1c";
  const char public_b[] = "\xd1\x73\x28\x99\xf6\x11\xcd\x89\x94\x03\x4d\x7f\x41"
                          "\x3d\xc9\x57\x63\x0e\x54\x93\xc2\x85\xac\xa4\x00\x65"
                          "\xcb\x63\x11\xbe\x69\x6b";
  const char public_c[] = "\xf4\x4d\xa3\x67\xa8\x8e\xe6\x56\x4f\x02\x02\x11\x45"
                          "\x67\x27\x08\x2f\x5c\xeb\xee\x8b\x1b\xf5\xeb\x73\x37"
                          "\x34\x1b\x45\x9b\x39\x22";
  const uint16_t listen_a = 20001;
  const uint16_t listen_b = 20002;
  const uint16_t listen_c = 20003;
  const uint16_t af_inet = AF_INET;
  const uint16_t af_inet6 = AF_INET6;
  /* Unused, but useful in case we change this:
  const struct sockaddr_in endpoint_a_v4 = {
      .sin_family = AF_INET,
      .sin_port = htons(listen_a),
      .sin_addr = {htonl(INADDR_LOOPBACK)}};*/
  const struct sockaddr_in endpoint_b_v4 = {
      .sin_family = AF_INET,
      .sin_port = htons(listen_b),
      .sin_addr = {htonl(INADDR_LOOPBACK)}};
  const struct sockaddr_in endpoint_c_v4 = {
      .sin_family = AF_INET,
      .sin_port = htons(listen_c),
      .sin_addr = {htonl(INADDR_LOOPBACK)}};
  struct sockaddr_in6 endpoint_a_v6 = {.sin6_family = AF_INET6,
                                       .sin6_port = htons(listen_a)};
  endpoint_a_v6.sin6_addr = in6addr_loopback;
  /* Unused, but useful in case we change this:
  const struct sockaddr_in6 endpoint_b_v6 = {
      .sin6_family = AF_INET6,
      .sin6_port = htons(listen_b)};
  endpoint_b_v6.sin6_addr = in6addr_loopback; */
  struct sockaddr_in6 endpoint_c_v6 = {.sin6_family = AF_INET6,
                                       .sin6_port = htons(listen_c)};
  endpoint_c_v6.sin6_addr = in6addr_loopback;
  const struct in_addr first_half_v4 = {0};
  const struct in_addr second_half_v4 = {htonl(128 << 24)};
  const struct in6_addr first_half_v6 = {{{0}}};
  const struct in6_addr second_half_v6 = {{{0x80}}};
  const uint8_t half_cidr = 1;
  const uint16_t persistent_keepalives[] = {1, 3, 7, 9, 14, 19};
  struct genlmsghdr genlhdr = {.cmd = WG_CMD_SET_DEVICE, .version = 1};
  int sock;
  int id, err;
  sock = socket(AF_NETLINK, SOCK_RAW, NETLINK_GENERIC);
  if (sock == -1)
    exit(1);
  id = netlink_wireguard_id_get(&nlmsg, sock);
  if (id == -1)
    goto error;
  netlink_init(&nlmsg, id, 0, &genlhdr, sizeof(genlhdr));
  netlink_attr(&nlmsg, WGDEVICE_A_IFNAME, ifname_a, strlen(ifname_a) + 1);
  netlink_attr(&nlmsg, WGDEVICE_A_PRIVATE_KEY, private_a, 32);
  netlink_attr(&nlmsg, WGDEVICE_A_LISTEN_PORT, &listen_a, 2);
  netlink_nest(&nlmsg, NLA_F_NESTED | WGDEVICE_A_PEERS);
  netlink_nest(&nlmsg, NLA_F_NESTED | 0);
  netlink_attr(&nlmsg, WGPEER_A_PUBLIC_KEY, public_b, 32);
  netlink_attr(&nlmsg, WGPEER_A_ENDPOINT, &endpoint_b_v4,
               sizeof(endpoint_b_v4));
  netlink_attr(&nlmsg, WGPEER_A_PERSISTENT_KEEPALIVE_INTERVAL,
               &persistent_keepalives[0], 2);
  netlink_nest(&nlmsg, NLA_F_NESTED | WGPEER_A_ALLOWEDIPS);
  netlink_nest(&nlmsg, NLA_F_NESTED | 0);
  netlink_attr(&nlmsg, WGALLOWEDIP_A_FAMILY, &af_inet, 2);
  netlink_attr(&nlmsg, WGALLOWEDIP_A_IPADDR, &first_half_v4,
               sizeof(first_half_v4));
  netlink_attr(&nlmsg, WGALLOWEDIP_A_CIDR_MASK, &half_cidr, 1);
  netlink_done(&nlmsg);
  netlink_nest(&nlmsg, NLA_F_NESTED | 0);
  netlink_attr(&nlmsg, WGALLOWEDIP_A_FAMILY, &af_inet6, 2);
  netlink_attr(&nlmsg, WGALLOWEDIP_A_IPADDR, &first_half_v6,
               sizeof(first_half_v6));
  netlink_attr(&nlmsg, WGALLOWEDIP_A_CIDR_MASK, &half_cidr, 1);
  netlink_done(&nlmsg);
  netlink_done(&nlmsg);
  netlink_done(&nlmsg);
  netlink_nest(&nlmsg, NLA_F_NESTED | 0);
  netlink_attr(&nlmsg, WGPEER_A_PUBLIC_KEY, public_c, 32);
  netlink_attr(&nlmsg, WGPEER_A_ENDPOINT, &endpoint_c_v6,
               sizeof(endpoint_c_v6));
  netlink_attr(&nlmsg, WGPEER_A_PERSISTENT_KEEPALIVE_INTERVAL,
               &persistent_keepalives[1], 2);
  netlink_nest(&nlmsg, NLA_F_NESTED | WGPEER_A_ALLOWEDIPS);
  netlink_nest(&nlmsg, NLA_F_NESTED | 0);
  netlink_attr(&nlmsg, WGALLOWEDIP_A_FAMILY, &af_inet, 2);
  netlink_attr(&nlmsg, WGALLOWEDIP_A_IPADDR, &second_half_v4,
               sizeof(second_half_v4));
  netlink_attr(&nlmsg, WGALLOWEDIP_A_CIDR_MASK, &half_cidr, 1);
  netlink_done(&nlmsg);
  netlink_nest(&nlmsg, NLA_F_NESTED | 0);
  netlink_attr(&nlmsg, WGALLOWEDIP_A_FAMILY, &af_inet6, 2);
  netlink_attr(&nlmsg, WGALLOWEDIP_A_IPADDR, &second_half_v6,
               sizeof(second_half_v6));
  netlink_attr(&nlmsg, WGALLOWEDIP_A_CIDR_MASK, &half_cidr, 1);
  netlink_done(&nlmsg);
  netlink_done(&nlmsg);
  netlink_done(&nlmsg);
  netlink_done(&nlmsg);
  err = netlink_send(&nlmsg, sock);
  if (err) {
  }
  netlink_init(&nlmsg, id, 0, &genlhdr, sizeof(genlhdr));
  netlink_attr(&nlmsg, WGDEVICE_A_IFNAME, ifname_b, strlen(ifname_b) + 1);
  netlink_attr(&nlmsg, WGDEVICE_A_PRIVATE_KEY, private_b, 32);
  netlink_attr(&nlmsg, WGDEVICE_A_LISTEN_PORT, &listen_b, 2);
  netlink_nest(&nlmsg, NLA_F_NESTED | WGDEVICE_A_PEERS);
  netlink_nest(&nlmsg, NLA_F_NESTED | 0);
  netlink_attr(&nlmsg, WGPEER_A_PUBLIC_KEY, public_a, 32);
  netlink_attr(&nlmsg, WGPEER_A_ENDPOINT, &endpoint_a_v6,
               sizeof(endpoint_a_v6));
  netlink_attr(&nlmsg, WGPEER_A_PERSISTENT_KEEPALIVE_INTERVAL,
               &persistent_keepalives[2], 2);
  netlink_nest(&nlmsg, NLA_F_NESTED | WGPEER_A_ALLOWEDIPS);
  netlink_nest(&nlmsg, NLA_F_NESTED | 0);
  netlink_attr(&nlmsg, WGALLOWEDIP_A_FAMILY, &af_inet, 2);
  netlink_attr(&nlmsg, WGALLOWEDIP_A_IPADDR, &first_half_v4,
               sizeof(first_half_v4));
  netlink_attr(&nlmsg, WGALLOWEDIP_A_CIDR_MASK, &half_cidr, 1);
  netlink_done(&nlmsg);
  netlink_nest(&nlmsg, NLA_F_NESTED | 0);
  netlink_attr(&nlmsg, WGALLOWEDIP_A_FAMILY, &af_inet6, 2);
  netlink_attr(&nlmsg, WGALLOWEDIP_A_IPADDR, &first_half_v6,
               sizeof(first_half_v6));
  netlink_attr(&nlmsg, WGALLOWEDIP_A_CIDR_MASK, &half_cidr, 1);
  netlink_done(&nlmsg);
  netlink_done(&nlmsg);
  netlink_done(&nlmsg);
  netlink_nest(&nlmsg, NLA_F_NESTED | 0);
  netlink_attr(&nlmsg, WGPEER_A_PUBLIC_KEY, public_c, 32);
  netlink_attr(&nlmsg, WGPEER_A_ENDPOINT, &endpoint_c_v4,
               sizeof(endpoint_c_v4));
  netlink_attr(&nlmsg, WGPEER_A_PERSISTENT_KEEPALIVE_INTERVAL,
               &persistent_keepalives[3], 2);
  netlink_nest(&nlmsg, NLA_F_NESTED | WGPEER_A_ALLOWEDIPS);
  netlink_nest(&nlmsg, NLA_F_NESTED | 0);
  netlink_attr(&nlmsg, WGALLOWEDIP_A_FAMILY, &af_inet, 2);
  netlink_attr(&nlmsg, WGALLOWEDIP_A_IPADDR, &second_half_v4,
               sizeof(second_half_v4));
  netlink_attr(&nlmsg, WGALLOWEDIP_A_CIDR_MASK, &half_cidr, 1);
  netlink_done(&nlmsg);
  netlink_nest(&nlmsg, NLA_F_NESTED | 0);
  netlink_attr(&nlmsg, WGALLOWEDIP_A_FAMILY, &af_inet6, 2);
  netlink_attr(&nlmsg, WGALLOWEDIP_A_IPADDR, &second_half_v6,
               sizeof(second_half_v6));
  netlink_attr(&nlmsg, WGALLOWEDIP_A_CIDR_MASK, &half_cidr, 1);
  netlink_done(&nlmsg);
  netlink_done(&nlmsg);
  netlink_done(&nlmsg);
  netlink_done(&nlmsg);
  err = netlink_send(&nlmsg, sock);
  if (err) {
  }
  netlink_init(&nlmsg, id, 0, &genlhdr, sizeof(genlhdr));
  netlink_attr(&nlmsg, WGDEVICE_A_IFNAME, ifname_c, strlen(ifname_c) + 1);
  netlink_attr(&nlmsg, WGDEVICE_A_PRIVATE_KEY, private_c, 32);
  netlink_attr(&nlmsg, WGDEVICE_A_LISTEN_PORT, &listen_c, 2);
  netlink_nest(&nlmsg, NLA_F_NESTED | WGDEVICE_A_PEERS);
  netlink_nest(&nlmsg, NLA_F_NESTED | 0);
  netlink_attr(&nlmsg, WGPEER_A_PUBLIC_KEY, public_a, 32);
  netlink_attr(&nlmsg, WGPEER_A_ENDPOINT, &endpoint_a_v6,
               sizeof(endpoint_a_v6));
  netlink_attr(&nlmsg, WGPEER_A_PERSISTENT_KEEPALIVE_INTERVAL,
               &persistent_keepalives[4], 2);
  netlink_nest(&nlmsg, NLA_F_NESTED | WGPEER_A_ALLOWEDIPS);
  netlink_nest(&nlmsg, NLA_F_NESTED | 0);
  netlink_attr(&nlmsg, WGALLOWEDIP_A_FAMILY, &af_inet, 2);
  netlink_attr(&nlmsg, WGALLOWEDIP_A_IPADDR, &first_half_v4,
               sizeof(first_half_v4));
  netlink_attr(&nlmsg, WGALLOWEDIP_A_CIDR_MASK, &half_cidr, 1);
  netlink_done(&nlmsg);
  netlink_nest(&nlmsg, NLA_F_NESTED | 0);
  netlink_attr(&nlmsg, WGALLOWEDIP_A_FAMILY, &af_inet6, 2);
  netlink_attr(&nlmsg, WGALLOWEDIP_A_IPADDR, &first_half_v6,
               sizeof(first_half_v6));
  netlink_attr(&nlmsg, WGALLOWEDIP_A_CIDR_MASK, &half_cidr, 1);
  netlink_done(&nlmsg);
  netlink_done(&nlmsg);
  netlink_done(&nlmsg);
  netlink_nest(&nlmsg, NLA_F_NESTED | 0);
  netlink_attr(&nlmsg, WGPEER_A_PUBLIC_KEY, public_b, 32);
  netlink_attr(&nlmsg, WGPEER_A_ENDPOINT, &endpoint_b_v4,
               sizeof(endpoint_b_v4));
  netlink_attr(&nlmsg, WGPEER_A_PERSISTENT_KEEPALIVE_INTERVAL,
               &persistent_keepalives[5], 2);
  netlink_nest(&nlmsg, NLA_F_NESTED | WGPEER_A_ALLOWEDIPS);
  netlink_nest(&nlmsg, NLA_F_NESTED | 0);
  netlink_attr(&nlmsg, WGALLOWEDIP_A_FAMILY, &af_inet, 2);
  netlink_attr(&nlmsg, WGALLOWEDIP_A_IPADDR, &second_half_v4,
               sizeof(second_half_v4));
  netlink_attr(&nlmsg, WGALLOWEDIP_A_CIDR_MASK, &half_cidr, 1);
  netlink_done(&nlmsg);
  netlink_nest(&nlmsg, NLA_F_NESTED | 0);
  netlink_attr(&nlmsg, WGALLOWEDIP_A_FAMILY, &af_inet6, 2);
  netlink_attr(&nlmsg, WGALLOWEDIP_A_IPADDR, &second_half_v6,
               sizeof(second_half_v6));
  netlink_attr(&nlmsg, WGALLOWEDIP_A_CIDR_MASK, &half_cidr, 1);
  netlink_done(&nlmsg);
  netlink_done(&nlmsg);
  netlink_done(&nlmsg);
  netlink_done(&nlmsg);
  err = netlink_send(&nlmsg, sock);
  if (err) {
  }

error:
  close(sock);
}
static void initialize_netdevices(void)
{
  char netdevsim[16];
  sprintf(netdevsim, "netdevsim%d", (int)procid);
  struct {
    const char* type;
    const char* dev;
  } devtypes[] = {
      {"ip6gretap", "ip6gretap0"}, {"bridge", "bridge0"},
      {"vcan", "vcan0"},           {"bond", "bond0"},
      {"team", "team0"},           {"dummy", "dummy0"},
      {"nlmon", "nlmon0"},         {"caif", "caif0"},
      {"batadv", "batadv0"},       {"vxcan", "vxcan1"},
      {"netdevsim", netdevsim},    {"veth", 0},
      {"xfrm", "xfrm0"},           {"wireguard", "wg0"},
      {"wireguard", "wg1"},        {"wireguard", "wg2"},
  };
  const char* devmasters[] = {"bridge", "bond", "team", "batadv"};
  struct {
    const char* name;
    int macsize;
    bool noipv6;
  } devices[] = {
      {"lo", ETH_ALEN},
      {"sit0", 0},
      {"bridge0", ETH_ALEN},
      {"vcan0", 0, true},
      {"tunl0", 0},
      {"gre0", 0},
      {"gretap0", ETH_ALEN},
      {"ip_vti0", 0},
      {"ip6_vti0", 0},
      {"ip6tnl0", 0},
      {"ip6gre0", 0},
      {"ip6gretap0", ETH_ALEN},
      {"erspan0", ETH_ALEN},
      {"bond0", ETH_ALEN},
      {"veth0", ETH_ALEN},
      {"veth1", ETH_ALEN},
      {"team0", ETH_ALEN},
      {"veth0_to_bridge", ETH_ALEN},
      {"veth1_to_bridge", ETH_ALEN},
      {"veth0_to_bond", ETH_ALEN},
      {"veth1_to_bond", ETH_ALEN},
      {"veth0_to_team", ETH_ALEN},
      {"veth1_to_team", ETH_ALEN},
      {"veth0_to_hsr", ETH_ALEN},
      {"veth1_to_hsr", ETH_ALEN},
      {"hsr0", 0},
      {"dummy0", ETH_ALEN},
      {"nlmon0", 0},
      {"vxcan0", 0, true},
      {"vxcan1", 0, true},
      {"caif0", ETH_ALEN},
      {"batadv0", ETH_ALEN},
      {netdevsim, ETH_ALEN},
      {"xfrm0", ETH_ALEN},
      {"veth0_virt_wifi", ETH_ALEN},
      {"veth1_virt_wifi", ETH_ALEN},
      {"virt_wifi0", ETH_ALEN},
      {"veth0_vlan", ETH_ALEN},
      {"veth1_vlan", ETH_ALEN},
      {"vlan0", ETH_ALEN},
      {"vlan1", ETH_ALEN},
      {"macvlan0", ETH_ALEN},
      {"macvlan1", ETH_ALEN},
      {"ipvlan0", ETH_ALEN},
      {"ipvlan1", ETH_ALEN},
      {"veth0_macvtap", ETH_ALEN},
      {"veth1_macvtap", ETH_ALEN},
      {"macvtap0", ETH_ALEN},
      {"macsec0", ETH_ALEN},
      {"veth0_to_batadv", ETH_ALEN},
      {"veth1_to_batadv", ETH_ALEN},
      {"batadv_slave_0", ETH_ALEN},
      {"batadv_slave_1", ETH_ALEN},
      {"geneve0", ETH_ALEN},
      {"geneve1", ETH_ALEN},
      {"wg0", 0},
      {"wg1", 0},
      {"wg2", 0},
  };
  int sock = socket(AF_NETLINK, SOCK_RAW, NETLINK_ROUTE);
  if (sock == -1)
    exit(1);
  unsigned i;
  for (i = 0; i < sizeof(devtypes) / sizeof(devtypes[0]); i++)
    netlink_add_device(&nlmsg, sock, devtypes[i].type, devtypes[i].dev);
  for (i = 0; i < sizeof(devmasters) / (sizeof(devmasters[0])); i++) {
    char master[32], slave0[32], veth0[32], slave1[32], veth1[32];
    sprintf(slave0, "%s_slave_0", devmasters[i]);
    sprintf(veth0, "veth0_to_%s", devmasters[i]);
    netlink_add_veth(&nlmsg, sock, slave0, veth0);
    sprintf(slave1, "%s_slave_1", devmasters[i]);
    sprintf(veth1, "veth1_to_%s", devmasters[i]);
    netlink_add_veth(&nlmsg, sock, slave1, veth1);
    sprintf(master, "%s0", devmasters[i]);
    netlink_device_change(&nlmsg, sock, slave0, false, master, 0, 0, NULL);
    netlink_device_change(&nlmsg, sock, slave1, false, master, 0, 0, NULL);
  }
  netlink_device_change(&nlmsg, sock, "bridge_slave_0", true, 0, 0, 0, NULL);
  netlink_device_change(&nlmsg, sock, "bridge_slave_1", true, 0, 0, 0, NULL);
  netlink_add_veth(&nlmsg, sock, "hsr_slave_0", "veth0_to_hsr");
  netlink_add_veth(&nlmsg, sock, "hsr_slave_1", "veth1_to_hsr");
  netlink_add_hsr(&nlmsg, sock, "hsr0", "hsr_slave_0", "hsr_slave_1");
  netlink_device_change(&nlmsg, sock, "hsr_slave_0", true, 0, 0, 0, NULL);
  netlink_device_change(&nlmsg, sock, "hsr_slave_1", true, 0, 0, 0, NULL);
  netlink_add_veth(&nlmsg, sock, "veth0_virt_wifi", "veth1_virt_wifi");
  netlink_add_linked(&nlmsg, sock, "virt_wifi", "virt_wifi0",
                     "veth1_virt_wifi");
  netlink_add_veth(&nlmsg, sock, "veth0_vlan", "veth1_vlan");
  netlink_add_vlan(&nlmsg, sock, "vlan0", "veth0_vlan", 0, htons(ETH_P_8021Q));
  netlink_add_vlan(&nlmsg, sock, "vlan1", "veth0_vlan", 1, htons(ETH_P_8021AD));
  netlink_add_macvlan(&nlmsg, sock, "macvlan0", "veth1_vlan");
  netlink_add_macvlan(&nlmsg, sock, "macvlan1", "veth1_vlan");
  netlink_add_ipvlan(&nlmsg, sock, "ipvlan0", "veth0_vlan", IPVLAN_MODE_L2, 0);
  netlink_add_ipvlan(&nlmsg, sock, "ipvlan1", "veth0_vlan", IPVLAN_MODE_L3S,
                     IPVLAN_F_VEPA);
  netlink_add_veth(&nlmsg, sock, "veth0_macvtap", "veth1_macvtap");
  netlink_add_linked(&nlmsg, sock, "macvtap", "macvtap0", "veth0_macvtap");
  netlink_add_linked(&nlmsg, sock, "macsec", "macsec0", "veth1_macvtap");
  char addr[32];
  sprintf(addr, DEV_IPV4, 14 + 10);
  struct in_addr geneve_addr4;
  if (inet_pton(AF_INET, addr, &geneve_addr4) <= 0)
    exit(1);
  struct in6_addr geneve_addr6;
  if (inet_pton(AF_INET6, "fc00::01", &geneve_addr6) <= 0)
    exit(1);
  netlink_add_geneve(&nlmsg, sock, "geneve0", 0, &geneve_addr4, 0);
  netlink_add_geneve(&nlmsg, sock, "geneve1", 1, 0, &geneve_addr6);
  netdevsim_add((int)procid, 4);
  netlink_wireguard_setup();
  for (i = 0; i < sizeof(devices) / (sizeof(devices[0])); i++) {
    char addr[32];
    sprintf(addr, DEV_IPV4, i + 10);
    netlink_add_addr4(&nlmsg, sock, devices[i].name, addr);
    if (!devices[i].noipv6) {
      sprintf(addr, DEV_IPV6, i + 10);
      netlink_add_addr6(&nlmsg, sock, devices[i].name, addr);
    }
    uint64_t macaddr = DEV_MAC + ((i + 10ull) << 40);
    netlink_device_change(&nlmsg, sock, devices[i].name, true, 0, &macaddr,
                          devices[i].macsize, NULL);
  }
  close(sock);
}
static void initialize_netdevices_init(void)
{
  int sock = socket(AF_NETLINK, SOCK_RAW, NETLINK_ROUTE);
  if (sock == -1)
    exit(1);
  struct {
    const char* type;
    int macsize;
    bool noipv6;
    bool noup;
  } devtypes[] = {
      {"nr", 7, true}, {"rose", 5, true, true},
  };
  unsigned i;
  for (i = 0; i < sizeof(devtypes) / sizeof(devtypes[0]); i++) {
    char dev[32], addr[32];
    sprintf(dev, "%s%d", devtypes[i].type, (int)procid);
    sprintf(addr, "172.30.%d.%d", i, (int)procid + 1);
    netlink_add_addr4(&nlmsg, sock, dev, addr);
    if (!devtypes[i].noipv6) {
      sprintf(addr, "fe88::%02x:%02x", i, (int)procid + 1);
      netlink_add_addr6(&nlmsg, sock, dev, addr);
    }
    int macsize = devtypes[i].macsize;
    uint64_t macaddr = 0xbbbbbb +
                       ((unsigned long long)i << (8 * (macsize - 2))) +
                       (procid << (8 * (macsize - 1)));
    netlink_device_change(&nlmsg, sock, dev, !devtypes[i].noup, 0, &macaddr,
                          macsize, NULL);
  }
  close(sock);
}

static int read_tun(char* data, int size)
{
  if (tunfd < 0)
    return -1;
  int rv = read(tunfd, data, size);
  if (rv < 0) {
    if (errno == EAGAIN)
      return -1;
    if (errno == EBADFD)
      return -1;
    exit(1);
  }
  return rv;
}

static void flush_tun()
{
  char data[1000];
  while (read_tun(&data[0], sizeof(data)) != -1) {
  }
}

#define MAX_FDS 30

static void setup_common()
{
  if (mount(0, "/sys/fs/fuse/connections", "fusectl", 0, 0)) {
  }
}

static void loop();

static void sandbox_common()
{
  prctl(PR_SET_PDEATHSIG, SIGKILL, 0, 0, 0);
  setpgrp();
  setsid();
  struct rlimit rlim;
  rlim.rlim_cur = rlim.rlim_max = (200 << 20);
  setrlimit(RLIMIT_AS, &rlim);
  rlim.rlim_cur = rlim.rlim_max = 32 << 20;
  setrlimit(RLIMIT_MEMLOCK, &rlim);
  rlim.rlim_cur = rlim.rlim_max = 136 << 20;
  setrlimit(RLIMIT_FSIZE, &rlim);
  rlim.rlim_cur = rlim.rlim_max = 1 << 20;
  setrlimit(RLIMIT_STACK, &rlim);
  rlim.rlim_cur = rlim.rlim_max = 0;
  setrlimit(RLIMIT_CORE, &rlim);
  rlim.rlim_cur = rlim.rlim_max = 256;
  setrlimit(RLIMIT_NOFILE, &rlim);
  if (unshare(CLONE_NEWNS)) {
  }
  if (unshare(CLONE_NEWIPC)) {
  }
  if (unshare(0x02000000)) {
  }
  if (unshare(CLONE_NEWUTS)) {
  }
  if (unshare(CLONE_SYSVSEM)) {
  }
  typedef struct {
    const char* name;
    const char* value;
  } sysctl_t;
  static const sysctl_t sysctls[] = {
      {"/proc/sys/kernel/shmmax", "16777216"},
      {"/proc/sys/kernel/shmall", "536870912"},
      {"/proc/sys/kernel/shmmni", "1024"},
      {"/proc/sys/kernel/msgmax", "8192"},
      {"/proc/sys/kernel/msgmni", "1024"},
      {"/proc/sys/kernel/msgmnb", "1024"},
      {"/proc/sys/kernel/sem", "1024 1048576 500 1024"},
  };
  unsigned i;
  for (i = 0; i < sizeof(sysctls) / sizeof(sysctls[0]); i++)
    write_file(sysctls[i].name, sysctls[i].value);
}

int wait_for_loop(int pid)
{
  if (pid < 0)
    exit(1);
  int status = 0;
  while (waitpid(-1, &status, __WALL) != pid) {
  }
  return WEXITSTATUS(status);
}

static void drop_caps(void)
{
  struct __user_cap_header_struct cap_hdr = {};
  struct __user_cap_data_struct cap_data[2] = {};
  cap_hdr.version = _LINUX_CAPABILITY_VERSION_3;
  cap_hdr.pid = getpid();
  if (syscall(SYS_capget, &cap_hdr, &cap_data))
    exit(1);
  const int drop = (1 << CAP_SYS_PTRACE) | (1 << CAP_SYS_NICE);
  cap_data[0].effective &= ~drop;
  cap_data[0].permitted &= ~drop;
  cap_data[0].inheritable &= ~drop;
  if (syscall(SYS_capset, &cap_hdr, &cap_data))
    exit(1);
}

static int do_sandbox_none(void)
{
  int pid = fork();
  if (pid != 0)
    return wait_for_loop(pid);
  setup_common();
  sandbox_common();
  drop_caps();
  initialize_netdevices_init();
  if (unshare(CLONE_NEWNET)) {
  }
  initialize_tun();
  initialize_netdevices();
  loop();
  exit(1);
}

static void kill_and_wait(int pid, int* status)
{
  kill(-pid, SIGKILL);
  kill(pid, SIGKILL);
  int i;
  for (i = 0; i < 100; i++) {
    if (waitpid(-1, status, WNOHANG | __WALL) == pid)
      return;
    usleep(1000);
  }
  DIR* dir = opendir("/sys/fs/fuse/connections");
  if (dir) {
    for (;;) {
      struct dirent* ent = readdir(dir);
      if (!ent)
        break;
      if (strcmp(ent->d_name, ".") == 0 || strcmp(ent->d_name, "..") == 0)
        continue;
      char abort[300];
      snprintf(abort, sizeof(abort), "/sys/fs/fuse/connections/%s/abort",
               ent->d_name);
      int fd = open(abort, O_WRONLY);
      if (fd == -1) {
        continue;
      }
      if (write(fd, abort, 1) < 0) {
      }
      close(fd);
    }
    closedir(dir);
  } else {
  }
  while (waitpid(-1, status, __WALL) != pid) {
  }
}

static void setup_test()
{
  prctl(PR_SET_PDEATHSIG, SIGKILL, 0, 0, 0);
  setpgrp();
  write_file("/proc/self/oom_score_adj", "1000");
  flush_tun();
}

static void close_fds()
{
  int fd;
  for (fd = 3; fd < MAX_FDS; fd++)
    close(fd);
}

static void execute_one(void);

#define WAIT_FLAGS __WALL

static void loop(void)
{
  int iter;
  for (iter = 0;; iter++) {
    int pid = fork();
    if (pid < 0)
      exit(1);
    if (pid == 0) {
      setup_test();
      execute_one();
      close_fds();
      exit(0);
    }
    int status = 0;
    uint64_t start = current_time_ms();
    for (;;) {
      if (waitpid(-1, &status, WNOHANG | WAIT_FLAGS) == pid)
        break;
      sleep_ms(1);
      if (current_time_ms() - start < 5 * 1000)
        continue;
      kill_and_wait(pid, &status);
      break;
    }
  }
}

uint64_t r[5] = {0xffffffffffffffff, 0xffffffffffffffff, 0x0,
                 0xffffffffffffffff, 0xffffffffffffffff};

void execute_one(void)
{
  intptr_t res = 0;
  res = syscall(__NR_socket, 0x10ul, 3ul, 0ul);
  if (res != -1)
    r[0] = res;
  res = syscall(__NR_socket, 0x10ul, 3ul, 0xcul);
  if (res != -1)
    r[1] = res;
  memcpy((void*)0x200000c0, "team0\000\000\000\000\000\000\000\000\000\000\000",
         16);
  *(uint32_t*)0x200000d0 = 0;
  res = syscall(__NR_ioctl, r[1], 0x8933ul, 0x200000c0ul);
  if (res != -1)
    r[2] = *(uint32_t*)0x200000d0;
  *(uint64_t*)0x20000000 = 0;
  *(uint32_t*)0x20000008 = 0;
  *(uint64_t*)0x20000010 = 0x20000100;
  *(uint64_t*)0x20000100 = 0x200001c0;
  *(uint32_t*)0x200001c0 = 0x58;
  *(uint16_t*)0x200001c4 = 0x10;
  *(uint16_t*)0x200001c6 = 0x401;
  *(uint32_t*)0x200001c8 = 0;
  *(uint32_t*)0x200001cc = 0;
  *(uint8_t*)0x200001d0 = 0;
  *(uint8_t*)0x200001d1 = 0;
  *(uint16_t*)0x200001d2 = 0;
  *(uint32_t*)0x200001d4 = 0;
  *(uint32_t*)0x200001d8 = 0;
  *(uint32_t*)0x200001dc = 0;
  *(uint16_t*)0x200001e0 = 0x30;
  STORE_BY_BITMASK(uint16_t, , 0x200001e2, 0x12, 0, 14);
  STORE_BY_BITMASK(uint16_t, , 0x200001e3, 0, 6, 1);
  STORE_BY_BITMASK(uint16_t, , 0x200001e3, 1, 7, 1);
  *(uint16_t*)0x200001e4 = 8;
  *(uint16_t*)0x200001e6 = 1;
  memcpy((void*)0x200001e8, "sit\000", 4);
  *(uint16_t*)0x200001ec = 0x24;
  STORE_BY_BITMASK(uint16_t, , 0x200001ee, 2, 0, 14);
  STORE_BY_BITMASK(uint16_t, , 0x200001ef, 0, 6, 1);
  STORE_BY_BITMASK(uint16_t, , 0x200001ef, 1, 7, 1);
  *(uint16_t*)0x200001f0 = 5;
  *(uint16_t*)0x200001f2 = 0xa;
  *(uint8_t*)0x200001f4 = 1;
  *(uint16_t*)0x200001f8 = 8;
  *(uint16_t*)0x200001fa = 2;
  *(uint8_t*)0x200001fc = 0xac;
  *(uint8_t*)0x200001fd = 0x14;
  *(uint8_t*)0x200001fe = 0x14;
  *(uint8_t*)0x200001ff = 0xaa;
  *(uint16_t*)0x20000200 = 6;
  *(uint16_t*)0x20000202 = 0xd;
  *(uint16_t*)0x20000204 = 4;
  *(uint16_t*)0x20000208 = 6;
  *(uint16_t*)0x2000020a = 0x12;
  *(uint16_t*)0x2000020c = htobe16(0x4e23);
  *(uint16_t*)0x20000210 = 8;
  *(uint16_t*)0x20000212 = 0xa;
  *(uint32_t*)0x20000214 = r[2];
  *(uint64_t*)0x20000108 = 0x58;
  *(uint64_t*)0x20000018 = 1;
  *(uint64_t*)0x20000020 = 0;
  *(uint64_t*)0x20000028 = 0;
  *(uint32_t*)0x20000030 = 0;
  syscall(__NR_sendmsg, r[0], 0x20000000ul, 0ul);
  res = syscall(__NR_socket, 0x10ul, 3ul, 0ul);
  if (res != -1)
    r[3] = res;
  *(uint64_t*)0x20000140 = 0;
  *(uint32_t*)0x20000148 = 0;
  *(uint64_t*)0x20000150 = 0x20000200;
  *(uint64_t*)0x20000200 = 0x200000c0;
  memcpy((void*)0x200000c0, "\x68\x00\x00\x00\x10\x00\x01\x08\x00\x00\x00\x00"
                            "\x00\x00\x00\x00\x00\x00\x00\x00",
         20);
  *(uint32_t*)0x200000d4 = 0;
  memcpy((void*)0x200000d8,
         "\x00\x00\x00\x00\x04\x00\x00\x00\x14\x00\x1a\x80\x10\x00\x02\x80\x0c"
         "\x00\x01\x80\x08\x00\x04\x00\x00\x00\x00\x00\x08\x00\x1b\x00\x00\x00"
         "\x00\x00\x08\x00\x29\x00\x00\x00\x00\x00\x14\x00\x14\x00\x62\x6f\x6e"
         "\x64\x5f\x73\x6c\x61\x76\x65\x5f\x30\x00\x00\x00\x00\x08\x00\x0a\x00",
         68);
  *(uint32_t*)0x2000011c = 0;
  memcpy((void*)0x20000120, "\000\000\000\000\000\000\000\000", 8);
  *(uint64_t*)0x20000208 = 0x68;
  *(uint64_t*)0x20000158 = 1;
  *(uint64_t*)0x20000160 = 0;
  *(uint64_t*)0x20000168 = 0;
  *(uint32_t*)0x20000170 = 0;
  syscall(__NR_sendmsg, r[3], 0x20000140ul, 0x84ul);
  res = syscall(__NR_socket, 0x10ul, 2ul, 0ul);
  if (res != -1)
    r[4] = res;
  *(uint64_t*)0x20001640 = 0;
  *(uint32_t*)0x20001648 = 0;
  *(uint64_t*)0x20001650 = 0x20000140;
  *(uint64_t*)0x20000140 = 0x20001600;
  memcpy((void*)0x20001600, "\x2e\x00\x00\x00\x10\x00\x81\x88\x04\x0f\x80\xec"
                            "\xdb\x4c\xb9\xcc\xa7\x48\x0e\xf4\x3c\x00\x00\x00"
                            "\xe3\xbd\x6e\xfb\x44\x00\x09\x00\x0e\x00\x0a\x00"
                            "\x10\x00\x00\x00\x00\x80\x00\x00\x12\x01",
         46);
  *(uint64_t*)0x20000148 = 0x2e;
  *(uint64_t*)0x20001658 = 1;
  *(uint64_t*)0x20001660 = 0;
  *(uint64_t*)0x20001668 = 0;
  *(uint32_t*)0x20001670 = 0;
  syscall(__NR_sendmsg, r[4], 0x20001640ul, 0ul);
}
int main(void)
{
  syscall(__NR_mmap, 0x20000000ul, 0x1000000ul, 3ul, 0x32ul, -1, 0);
  for (procid = 0; procid < 6; procid++) {
    if (fork() == 0) {
      do_sandbox_none();
    }
  }
  sleep(1000000);
  return 0;
}


[-- Attachment #3: repro_macvlan2.c --]
[-- Type: text/plain, Size: 44416 bytes --]

// autogenerated by syzkaller (https://github.com/google/syzkaller)

#define _GNU_SOURCE

#include <arpa/inet.h>
#include <dirent.h>
#include <endian.h>
#include <errno.h>
#include <fcntl.h>
#include <net/if.h>
#include <net/if_arp.h>
#include <netinet/in.h>
#include <sched.h>
#include <signal.h>
#include <stdarg.h>
#include <stdbool.h>
#include <stdint.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <sys/ioctl.h>
#include <sys/mount.h>
#include <sys/prctl.h>
#include <sys/resource.h>
#include <sys/socket.h>
#include <sys/stat.h>
#include <sys/syscall.h>
#include <sys/time.h>
#include <sys/types.h>
#include <sys/uio.h>
#include <sys/wait.h>
#include <time.h>
#include <unistd.h>

#include <linux/capability.h>
#include <linux/genetlink.h>
#include <linux/if_addr.h>
#include <linux/if_ether.h>
#include <linux/if_link.h>
#include <linux/if_tun.h>
#include <linux/in6.h>
#include <linux/ip.h>
#include <linux/neighbour.h>
#include <linux/net.h>
#include <linux/netlink.h>
#include <linux/rtnetlink.h>
#include <linux/tcp.h>
#include <linux/veth.h>

unsigned long long procid;

static void sleep_ms(uint64_t ms)
{
  usleep(ms * 1000);
}

static uint64_t current_time_ms(void)
{
  struct timespec ts;
  if (clock_gettime(CLOCK_MONOTONIC, &ts))
    exit(1);
  return (uint64_t)ts.tv_sec * 1000 + (uint64_t)ts.tv_nsec / 1000000;
}

#define BITMASK(bf_off, bf_len) (((1ull << (bf_len)) - 1) << (bf_off))
#define STORE_BY_BITMASK(type, htobe, addr, val, bf_off, bf_len)               \
  *(type*)(addr) =                                                             \
      htobe((htobe(*(type*)(addr)) & ~BITMASK((bf_off), (bf_len))) |           \
            (((type)(val) << (bf_off)) & BITMASK((bf_off), (bf_len))))

static bool write_file(const char* file, const char* what, ...)
{
  char buf[1024];
  va_list args;
  va_start(args, what);
  vsnprintf(buf, sizeof(buf), what, args);
  va_end(args);
  buf[sizeof(buf) - 1] = 0;
  int len = strlen(buf);
  int fd = open(file, O_WRONLY | O_CLOEXEC);
  if (fd == -1)
    return false;
  if (write(fd, buf, len) != len) {
    int err = errno;
    close(fd);
    errno = err;
    return false;
  }
  close(fd);
  return true;
}

struct nlmsg {
  char* pos;
  int nesting;
  struct nlattr* nested[8];
  char buf[1024];
};

static struct nlmsg nlmsg;

static void netlink_init(struct nlmsg* nlmsg, int typ, int flags,
                         const void* data, int size)
{
  memset(nlmsg, 0, sizeof(*nlmsg));
  struct nlmsghdr* hdr = (struct nlmsghdr*)nlmsg->buf;
  hdr->nlmsg_type = typ;
  hdr->nlmsg_flags = NLM_F_REQUEST | NLM_F_ACK | flags;
  memcpy(hdr + 1, data, size);
  nlmsg->pos = (char*)(hdr + 1) + NLMSG_ALIGN(size);
}

static void netlink_attr(struct nlmsg* nlmsg, int typ, const void* data,
                         int size)
{
  struct nlattr* attr = (struct nlattr*)nlmsg->pos;
  attr->nla_len = sizeof(*attr) + size;
  attr->nla_type = typ;
  memcpy(attr + 1, data, size);
  nlmsg->pos += NLMSG_ALIGN(attr->nla_len);
}

static void netlink_nest(struct nlmsg* nlmsg, int typ)
{
  struct nlattr* attr = (struct nlattr*)nlmsg->pos;
  attr->nla_type = typ;
  nlmsg->pos += sizeof(*attr);
  nlmsg->nested[nlmsg->nesting++] = attr;
}

static void netlink_done(struct nlmsg* nlmsg)
{
  struct nlattr* attr = nlmsg->nested[--nlmsg->nesting];
  attr->nla_len = nlmsg->pos - (char*)attr;
}

static int netlink_send_ext(struct nlmsg* nlmsg, int sock, uint16_t reply_type,
                            int* reply_len)
{
  if (nlmsg->pos > nlmsg->buf + sizeof(nlmsg->buf) || nlmsg->nesting)
    exit(1);
  struct nlmsghdr* hdr = (struct nlmsghdr*)nlmsg->buf;
  hdr->nlmsg_len = nlmsg->pos - nlmsg->buf;
  struct sockaddr_nl addr;
  memset(&addr, 0, sizeof(addr));
  addr.nl_family = AF_NETLINK;
  unsigned n = sendto(sock, nlmsg->buf, hdr->nlmsg_len, 0,
                      (struct sockaddr*)&addr, sizeof(addr));
  if (n != hdr->nlmsg_len)
    exit(1);
  n = recv(sock, nlmsg->buf, sizeof(nlmsg->buf), 0);
  if (hdr->nlmsg_type == NLMSG_DONE) {
    *reply_len = 0;
    return 0;
  }
  if (n < sizeof(struct nlmsghdr))
    exit(1);
  if (reply_len && hdr->nlmsg_type == reply_type) {
    *reply_len = n;
    return 0;
  }
  if (n < sizeof(struct nlmsghdr) + sizeof(struct nlmsgerr))
    exit(1);
  if (hdr->nlmsg_type != NLMSG_ERROR)
    exit(1);
  return -((struct nlmsgerr*)(hdr + 1))->error;
}

static int netlink_send(struct nlmsg* nlmsg, int sock)
{
  return netlink_send_ext(nlmsg, sock, 0, NULL);
}

static int netlink_next_msg(struct nlmsg* nlmsg, unsigned int offset,
                            unsigned int total_len)
{
  struct nlmsghdr* hdr = (struct nlmsghdr*)(nlmsg->buf + offset);
  if (offset == total_len || offset + hdr->nlmsg_len > total_len)
    return -1;
  return hdr->nlmsg_len;
}

static void netlink_add_device_impl(struct nlmsg* nlmsg, const char* type,
                                    const char* name)
{
  struct ifinfomsg hdr;
  memset(&hdr, 0, sizeof(hdr));
  netlink_init(nlmsg, RTM_NEWLINK, NLM_F_EXCL | NLM_F_CREATE, &hdr,
               sizeof(hdr));
  if (name)
    netlink_attr(nlmsg, IFLA_IFNAME, name, strlen(name));
  netlink_nest(nlmsg, IFLA_LINKINFO);
  netlink_attr(nlmsg, IFLA_INFO_KIND, type, strlen(type));
}

static void netlink_add_device(struct nlmsg* nlmsg, int sock, const char* type,
                               const char* name)
{
  netlink_add_device_impl(nlmsg, type, name);
  netlink_done(nlmsg);
  int err = netlink_send(nlmsg, sock);
  (void)err;
}

static void netlink_add_veth(struct nlmsg* nlmsg, int sock, const char* name,
                             const char* peer)
{
  netlink_add_device_impl(nlmsg, "veth", name);
  netlink_nest(nlmsg, IFLA_INFO_DATA);
  netlink_nest(nlmsg, VETH_INFO_PEER);
  nlmsg->pos += sizeof(struct ifinfomsg);
  netlink_attr(nlmsg, IFLA_IFNAME, peer, strlen(peer));
  netlink_done(nlmsg);
  netlink_done(nlmsg);
  netlink_done(nlmsg);
  int err = netlink_send(nlmsg, sock);
  (void)err;
}

static void netlink_add_hsr(struct nlmsg* nlmsg, int sock, const char* name,
                            const char* slave1, const char* slave2)
{
  netlink_add_device_impl(nlmsg, "hsr", name);
  netlink_nest(nlmsg, IFLA_INFO_DATA);
  int ifindex1 = if_nametoindex(slave1);
  netlink_attr(nlmsg, IFLA_HSR_SLAVE1, &ifindex1, sizeof(ifindex1));
  int ifindex2 = if_nametoindex(slave2);
  netlink_attr(nlmsg, IFLA_HSR_SLAVE2, &ifindex2, sizeof(ifindex2));
  netlink_done(nlmsg);
  netlink_done(nlmsg);
  int err = netlink_send(nlmsg, sock);
  (void)err;
}

static void netlink_add_linked(struct nlmsg* nlmsg, int sock, const char* type,
                               const char* name, const char* link)
{
  netlink_add_device_impl(nlmsg, type, name);
  netlink_done(nlmsg);
  int ifindex = if_nametoindex(link);
  netlink_attr(nlmsg, IFLA_LINK, &ifindex, sizeof(ifindex));
  int err = netlink_send(nlmsg, sock);
  (void)err;
}

static void netlink_add_vlan(struct nlmsg* nlmsg, int sock, const char* name,
                             const char* link, uint16_t id, uint16_t proto)
{
  netlink_add_device_impl(nlmsg, "vlan", name);
  netlink_nest(nlmsg, IFLA_INFO_DATA);
  netlink_attr(nlmsg, IFLA_VLAN_ID, &id, sizeof(id));
  netlink_attr(nlmsg, IFLA_VLAN_PROTOCOL, &proto, sizeof(proto));
  netlink_done(nlmsg);
  netlink_done(nlmsg);
  int ifindex = if_nametoindex(link);
  netlink_attr(nlmsg, IFLA_LINK, &ifindex, sizeof(ifindex));
  int err = netlink_send(nlmsg, sock);
  (void)err;
}

static void netlink_add_macvlan(struct nlmsg* nlmsg, int sock, const char* name,
                                const char* link)
{
  netlink_add_device_impl(nlmsg, "macvlan", name);
  netlink_nest(nlmsg, IFLA_INFO_DATA);
  uint32_t mode = MACVLAN_MODE_BRIDGE;
  netlink_attr(nlmsg, IFLA_MACVLAN_MODE, &mode, sizeof(mode));
  netlink_done(nlmsg);
  netlink_done(nlmsg);
  int ifindex = if_nametoindex(link);
  netlink_attr(nlmsg, IFLA_LINK, &ifindex, sizeof(ifindex));
  int err = netlink_send(nlmsg, sock);
  (void)err;
}

static void netlink_add_geneve(struct nlmsg* nlmsg, int sock, const char* name,
                               uint32_t vni, struct in_addr* addr4,
                               struct in6_addr* addr6)
{
  netlink_add_device_impl(nlmsg, "geneve", name);
  netlink_nest(nlmsg, IFLA_INFO_DATA);
  netlink_attr(nlmsg, IFLA_GENEVE_ID, &vni, sizeof(vni));
  if (addr4)
    netlink_attr(nlmsg, IFLA_GENEVE_REMOTE, addr4, sizeof(*addr4));
  if (addr6)
    netlink_attr(nlmsg, IFLA_GENEVE_REMOTE6, addr6, sizeof(*addr6));
  netlink_done(nlmsg);
  netlink_done(nlmsg);
  int err = netlink_send(nlmsg, sock);
  (void)err;
}

#define IFLA_IPVLAN_FLAGS 2
#define IPVLAN_MODE_L3S 2
#undef IPVLAN_F_VEPA
#define IPVLAN_F_VEPA 2

static void netlink_add_ipvlan(struct nlmsg* nlmsg, int sock, const char* name,
                               const char* link, uint16_t mode, uint16_t flags)
{
  netlink_add_device_impl(nlmsg, "ipvlan", name);
  netlink_nest(nlmsg, IFLA_INFO_DATA);
  netlink_attr(nlmsg, IFLA_IPVLAN_MODE, &mode, sizeof(mode));
  netlink_attr(nlmsg, IFLA_IPVLAN_FLAGS, &flags, sizeof(flags));
  netlink_done(nlmsg);
  netlink_done(nlmsg);
  int ifindex = if_nametoindex(link);
  netlink_attr(nlmsg, IFLA_LINK, &ifindex, sizeof(ifindex));
  int err = netlink_send(nlmsg, sock);
  (void)err;
}

static void netlink_device_change(struct nlmsg* nlmsg, int sock,
                                  const char* name, bool up, const char* master,
                                  const void* mac, int macsize,
                                  const char* new_name)
{
  struct ifinfomsg hdr;
  memset(&hdr, 0, sizeof(hdr));
  if (up)
    hdr.ifi_flags = hdr.ifi_change = IFF_UP;
  hdr.ifi_index = if_nametoindex(name);
  netlink_init(nlmsg, RTM_NEWLINK, 0, &hdr, sizeof(hdr));
  if (new_name)
    netlink_attr(nlmsg, IFLA_IFNAME, new_name, strlen(new_name));
  if (master) {
    int ifindex = if_nametoindex(master);
    netlink_attr(nlmsg, IFLA_MASTER, &ifindex, sizeof(ifindex));
  }
  if (macsize)
    netlink_attr(nlmsg, IFLA_ADDRESS, mac, macsize);
  int err = netlink_send(nlmsg, sock);
  (void)err;
}

static int netlink_add_addr(struct nlmsg* nlmsg, int sock, const char* dev,
                            const void* addr, int addrsize)
{
  struct ifaddrmsg hdr;
  memset(&hdr, 0, sizeof(hdr));
  hdr.ifa_family = addrsize == 4 ? AF_INET : AF_INET6;
  hdr.ifa_prefixlen = addrsize == 4 ? 24 : 120;
  hdr.ifa_scope = RT_SCOPE_UNIVERSE;
  hdr.ifa_index = if_nametoindex(dev);
  netlink_init(nlmsg, RTM_NEWADDR, NLM_F_CREATE | NLM_F_REPLACE, &hdr,
               sizeof(hdr));
  netlink_attr(nlmsg, IFA_LOCAL, addr, addrsize);
  netlink_attr(nlmsg, IFA_ADDRESS, addr, addrsize);
  return netlink_send(nlmsg, sock);
}

static void netlink_add_addr4(struct nlmsg* nlmsg, int sock, const char* dev,
                              const char* addr)
{
  struct in_addr in_addr;
  inet_pton(AF_INET, addr, &in_addr);
  int err = netlink_add_addr(nlmsg, sock, dev, &in_addr, sizeof(in_addr));
  (void)err;
}

static void netlink_add_addr6(struct nlmsg* nlmsg, int sock, const char* dev,
                              const char* addr)
{
  struct in6_addr in6_addr;
  inet_pton(AF_INET6, addr, &in6_addr);
  int err = netlink_add_addr(nlmsg, sock, dev, &in6_addr, sizeof(in6_addr));
  (void)err;
}

static void netlink_add_neigh(struct nlmsg* nlmsg, int sock, const char* name,
                              const void* addr, int addrsize, const void* mac,
                              int macsize)
{
  struct ndmsg hdr;
  memset(&hdr, 0, sizeof(hdr));
  hdr.ndm_family = addrsize == 4 ? AF_INET : AF_INET6;
  hdr.ndm_ifindex = if_nametoindex(name);
  hdr.ndm_state = NUD_PERMANENT;
  netlink_init(nlmsg, RTM_NEWNEIGH, NLM_F_EXCL | NLM_F_CREATE, &hdr,
               sizeof(hdr));
  netlink_attr(nlmsg, NDA_DST, addr, addrsize);
  netlink_attr(nlmsg, NDA_LLADDR, mac, macsize);
  int err = netlink_send(nlmsg, sock);
  (void)err;
}

static int tunfd = -1;
static int tun_frags_enabled;

#define TUN_IFACE "syz_tun"

#define LOCAL_MAC 0xaaaaaaaaaaaa
#define REMOTE_MAC 0xaaaaaaaaaabb

#define LOCAL_IPV4 "172.20.20.170"
#define REMOTE_IPV4 "172.20.20.187"

#define LOCAL_IPV6 "fe80::aa"
#define REMOTE_IPV6 "fe80::bb"

#define IFF_NAPI 0x0010
#define IFF_NAPI_FRAGS 0x0020

static void initialize_tun(void)
{
  tunfd = open("/dev/net/tun", O_RDWR | O_NONBLOCK);
  if (tunfd == -1) {
    printf("tun: can't open /dev/net/tun: please enable CONFIG_TUN=y\n");
    printf("otherwise fuzzing or reproducing might not work as intended\n");
    return;
  }
  const int kTunFd = 240;
  if (dup2(tunfd, kTunFd) < 0)
    exit(1);
  close(tunfd);
  tunfd = kTunFd;
  struct ifreq ifr;
  memset(&ifr, 0, sizeof(ifr));
  strncpy(ifr.ifr_name, TUN_IFACE, IFNAMSIZ);
  ifr.ifr_flags = IFF_TAP | IFF_NO_PI;
  if (ioctl(tunfd, TUNSETIFF, (void*)&ifr) < 0) {
    exit(1);
  }
  char sysctl[64];
  sprintf(sysctl, "/proc/sys/net/ipv6/conf/%s/accept_dad", TUN_IFACE);
  write_file(sysctl, "0");
  sprintf(sysctl, "/proc/sys/net/ipv6/conf/%s/router_solicitations", TUN_IFACE);
  write_file(sysctl, "0");
  int sock = socket(AF_NETLINK, SOCK_RAW, NETLINK_ROUTE);
  if (sock == -1)
    exit(1);
  netlink_add_addr4(&nlmsg, sock, TUN_IFACE, LOCAL_IPV4);
  netlink_add_addr6(&nlmsg, sock, TUN_IFACE, LOCAL_IPV6);
  uint64_t macaddr = REMOTE_MAC;
  struct in_addr in_addr;
  inet_pton(AF_INET, REMOTE_IPV4, &in_addr);
  netlink_add_neigh(&nlmsg, sock, TUN_IFACE, &in_addr, sizeof(in_addr),
                    &macaddr, ETH_ALEN);
  struct in6_addr in6_addr;
  inet_pton(AF_INET6, REMOTE_IPV6, &in6_addr);
  netlink_add_neigh(&nlmsg, sock, TUN_IFACE, &in6_addr, sizeof(in6_addr),
                    &macaddr, ETH_ALEN);
  macaddr = LOCAL_MAC;
  netlink_device_change(&nlmsg, sock, TUN_IFACE, true, 0, &macaddr, ETH_ALEN,
                        NULL);
  close(sock);
}

#define DEVLINK_FAMILY_NAME "devlink"

#define DEVLINK_CMD_PORT_GET 5
#define DEVLINK_ATTR_BUS_NAME 1
#define DEVLINK_ATTR_DEV_NAME 2
#define DEVLINK_ATTR_NETDEV_NAME 7

static int netlink_devlink_id_get(struct nlmsg* nlmsg, int sock)
{
  struct genlmsghdr genlhdr;
  struct nlattr* attr;
  int err, n;
  uint16_t id = 0;
  memset(&genlhdr, 0, sizeof(genlhdr));
  genlhdr.cmd = CTRL_CMD_GETFAMILY;
  netlink_init(nlmsg, GENL_ID_CTRL, 0, &genlhdr, sizeof(genlhdr));
  netlink_attr(nlmsg, CTRL_ATTR_FAMILY_NAME, DEVLINK_FAMILY_NAME,
               strlen(DEVLINK_FAMILY_NAME) + 1);
  err = netlink_send_ext(nlmsg, sock, GENL_ID_CTRL, &n);
  if (err) {
    return -1;
  }
  attr = (struct nlattr*)(nlmsg->buf + NLMSG_HDRLEN +
                          NLMSG_ALIGN(sizeof(genlhdr)));
  for (; (char*)attr < nlmsg->buf + n;
       attr = (struct nlattr*)((char*)attr + NLMSG_ALIGN(attr->nla_len))) {
    if (attr->nla_type == CTRL_ATTR_FAMILY_ID) {
      id = *(uint16_t*)(attr + 1);
      break;
    }
  }
  if (!id) {
    return -1;
  }
  recv(sock, nlmsg->buf, sizeof(nlmsg->buf), 0); /* recv ack */
  return id;
}

static struct nlmsg nlmsg2;

static void initialize_devlink_ports(const char* bus_name, const char* dev_name,
                                     const char* netdev_prefix)
{
  struct genlmsghdr genlhdr;
  int len, total_len, id, err, offset;
  uint16_t netdev_index;
  int sock = socket(AF_NETLINK, SOCK_RAW, NETLINK_GENERIC);
  if (sock == -1)
    exit(1);
  int rtsock = socket(AF_NETLINK, SOCK_RAW, NETLINK_ROUTE);
  if (rtsock == -1)
    exit(1);
  id = netlink_devlink_id_get(&nlmsg, sock);
  if (id == -1)
    goto error;
  memset(&genlhdr, 0, sizeof(genlhdr));
  genlhdr.cmd = DEVLINK_CMD_PORT_GET;
  netlink_init(&nlmsg, id, NLM_F_DUMP, &genlhdr, sizeof(genlhdr));
  netlink_attr(&nlmsg, DEVLINK_ATTR_BUS_NAME, bus_name, strlen(bus_name) + 1);
  netlink_attr(&nlmsg, DEVLINK_ATTR_DEV_NAME, dev_name, strlen(dev_name) + 1);
  err = netlink_send_ext(&nlmsg, sock, id, &total_len);
  if (err) {
    goto error;
  }
  offset = 0;
  netdev_index = 0;
  while ((len = netlink_next_msg(&nlmsg, offset, total_len)) != -1) {
    struct nlattr* attr = (struct nlattr*)(nlmsg.buf + offset + NLMSG_HDRLEN +
                                           NLMSG_ALIGN(sizeof(genlhdr)));
    for (; (char*)attr < nlmsg.buf + offset + len;
         attr = (struct nlattr*)((char*)attr + NLMSG_ALIGN(attr->nla_len))) {
      if (attr->nla_type == DEVLINK_ATTR_NETDEV_NAME) {
        char* port_name;
        char netdev_name[IFNAMSIZ];
        port_name = (char*)(attr + 1);
        snprintf(netdev_name, sizeof(netdev_name), "%s%d", netdev_prefix,
                 netdev_index);
        netlink_device_change(&nlmsg2, rtsock, port_name, true, 0, 0, 0,
                              netdev_name);
        break;
      }
    }
    offset += len;
    netdev_index++;
  }
error:
  close(rtsock);
  close(sock);
}

#define DEV_IPV4 "172.20.20.%d"
#define DEV_IPV6 "fe80::%02x"
#define DEV_MAC 0x00aaaaaaaaaa

static void netdevsim_add(unsigned int addr, unsigned int port_count)
{
  char buf[16];
  sprintf(buf, "%u %u", addr, port_count);
  if (write_file("/sys/bus/netdevsim/new_device", buf)) {
    snprintf(buf, sizeof(buf), "netdevsim%d", addr);
    initialize_devlink_ports("netdevsim", buf, "netdevsim");
  }
}

#define WG_GENL_NAME "wireguard"
enum wg_cmd {
  WG_CMD_GET_DEVICE,
  WG_CMD_SET_DEVICE,
};
enum wgdevice_attribute {
  WGDEVICE_A_UNSPEC,
  WGDEVICE_A_IFINDEX,
  WGDEVICE_A_IFNAME,
  WGDEVICE_A_PRIVATE_KEY,
  WGDEVICE_A_PUBLIC_KEY,
  WGDEVICE_A_FLAGS,
  WGDEVICE_A_LISTEN_PORT,
  WGDEVICE_A_FWMARK,
  WGDEVICE_A_PEERS,
};
enum wgpeer_attribute {
  WGPEER_A_UNSPEC,
  WGPEER_A_PUBLIC_KEY,
  WGPEER_A_PRESHARED_KEY,
  WGPEER_A_FLAGS,
  WGPEER_A_ENDPOINT,
  WGPEER_A_PERSISTENT_KEEPALIVE_INTERVAL,
  WGPEER_A_LAST_HANDSHAKE_TIME,
  WGPEER_A_RX_BYTES,
  WGPEER_A_TX_BYTES,
  WGPEER_A_ALLOWEDIPS,
  WGPEER_A_PROTOCOL_VERSION,
};
enum wgallowedip_attribute {
  WGALLOWEDIP_A_UNSPEC,
  WGALLOWEDIP_A_FAMILY,
  WGALLOWEDIP_A_IPADDR,
  WGALLOWEDIP_A_CIDR_MASK,
};

static int netlink_wireguard_id_get(struct nlmsg* nlmsg, int sock)
{
  struct genlmsghdr genlhdr;
  struct nlattr* attr;
  int err, n;
  uint16_t id = 0;
  memset(&genlhdr, 0, sizeof(genlhdr));
  genlhdr.cmd = CTRL_CMD_GETFAMILY;
  netlink_init(nlmsg, GENL_ID_CTRL, 0, &genlhdr, sizeof(genlhdr));
  netlink_attr(nlmsg, CTRL_ATTR_FAMILY_NAME, WG_GENL_NAME,
               strlen(WG_GENL_NAME) + 1);
  err = netlink_send_ext(nlmsg, sock, GENL_ID_CTRL, &n);
  if (err) {
    return -1;
  }
  attr = (struct nlattr*)(nlmsg->buf + NLMSG_HDRLEN +
                          NLMSG_ALIGN(sizeof(genlhdr)));
  for (; (char*)attr < nlmsg->buf + n;
       attr = (struct nlattr*)((char*)attr + NLMSG_ALIGN(attr->nla_len))) {
    if (attr->nla_type == CTRL_ATTR_FAMILY_ID) {
      id = *(uint16_t*)(attr + 1);
      break;
    }
  }
  if (!id) {
    return -1;
  }
  recv(sock, nlmsg->buf, sizeof(nlmsg->buf), 0); /* recv ack */
  return id;
}

static void netlink_wireguard_setup(void)
{
  const char ifname_a[] = "wg0";
  const char ifname_b[] = "wg1";
  const char ifname_c[] = "wg2";
  const char private_a[] =
      "\xa0\x5c\xa8\x4f\x6c\x9c\x8e\x38\x53\xe2\xfd\x7a\x70\xae\x0f\xb2\x0f\xa1"
      "\x52\x60\x0c\xb0\x08\x45\x17\x4f\x08\x07\x6f\x8d\x78\x43";
  const char private_b[] =
      "\xb0\x80\x73\xe8\xd4\x4e\x91\xe3\xda\x92\x2c\x22\x43\x82\x44\xbb\x88\x5c"
      "\x69\xe2\x69\xc8\xe9\xd8\x35\xb1\x14\x29\x3a\x4d\xdc\x6e";
  const char private_c[] =
      "\xa0\xcb\x87\x9a\x47\xf5\xbc\x64\x4c\x0e\x69\x3f\xa6\xd0\x31\xc7\x4a\x15"
      "\x53\xb6\xe9\x01\xb9\xff\x2f\x51\x8c\x78\x04\x2f\xb5\x42";
  const char public_a[] =
      "\x97\x5c\x9d\x81\xc9\x83\xc8\x20\x9e\xe7\x81\x25\x4b\x89\x9f\x8e\xd9\x25"
      "\xae\x9f\x09\x23\xc2\x3c\x62\xf5\x3c\x57\xcd\xbf\x69\x1c";
  const char public_b[] =
      "\xd1\x73\x28\x99\xf6\x11\xcd\x89\x94\x03\x4d\x7f\x41\x3d\xc9\x57\x63\x0e"
      "\x54\x93\xc2\x85\xac\xa4\x00\x65\xcb\x63\x11\xbe\x69\x6b";
  const char public_c[] =
      "\xf4\x4d\xa3\x67\xa8\x8e\xe6\x56\x4f\x02\x02\x11\x45\x67\x27\x08\x2f\x5c"
      "\xeb\xee\x8b\x1b\xf5\xeb\x73\x37\x34\x1b\x45\x9b\x39\x22";
  const uint16_t listen_a = 20001;
  const uint16_t listen_b = 20002;
  const uint16_t listen_c = 20003;
  const uint16_t af_inet = AF_INET;
  const uint16_t af_inet6 = AF_INET6;
  /* Unused, but useful in case we change this:
  const struct sockaddr_in endpoint_a_v4 = {
      .sin_family = AF_INET,
      .sin_port = htons(listen_a),
      .sin_addr = {htonl(INADDR_LOOPBACK)}};*/
  const struct sockaddr_in endpoint_b_v4 = {
      .sin_family = AF_INET,
      .sin_port = htons(listen_b),
      .sin_addr = {htonl(INADDR_LOOPBACK)}};
  const struct sockaddr_in endpoint_c_v4 = {
      .sin_family = AF_INET,
      .sin_port = htons(listen_c),
      .sin_addr = {htonl(INADDR_LOOPBACK)}};
  struct sockaddr_in6 endpoint_a_v6 = {.sin6_family = AF_INET6,
                                       .sin6_port = htons(listen_a)};
  endpoint_a_v6.sin6_addr = in6addr_loopback;
  /* Unused, but useful in case we change this:
  const struct sockaddr_in6 endpoint_b_v6 = {
      .sin6_family = AF_INET6,
      .sin6_port = htons(listen_b)};
  endpoint_b_v6.sin6_addr = in6addr_loopback; */
  struct sockaddr_in6 endpoint_c_v6 = {.sin6_family = AF_INET6,
                                       .sin6_port = htons(listen_c)};
  endpoint_c_v6.sin6_addr = in6addr_loopback;
  const struct in_addr first_half_v4 = {0};
  const struct in_addr second_half_v4 = {htonl(128 << 24)};
  const struct in6_addr first_half_v6 = {{{0}}};
  const struct in6_addr second_half_v6 = {{{0x80}}};
  const uint8_t half_cidr = 1;
  const uint16_t persistent_keepalives[] = {1, 3, 7, 9, 14, 19};
  struct genlmsghdr genlhdr = {.cmd = WG_CMD_SET_DEVICE, .version = 1};
  int sock;
  int id, err;
  sock = socket(AF_NETLINK, SOCK_RAW, NETLINK_GENERIC);
  if (sock == -1)
    exit(1);
  id = netlink_wireguard_id_get(&nlmsg, sock);
  if (id == -1)
    goto error;
  netlink_init(&nlmsg, id, 0, &genlhdr, sizeof(genlhdr));
  netlink_attr(&nlmsg, WGDEVICE_A_IFNAME, ifname_a, strlen(ifname_a) + 1);
  netlink_attr(&nlmsg, WGDEVICE_A_PRIVATE_KEY, private_a, 32);
  netlink_attr(&nlmsg, WGDEVICE_A_LISTEN_PORT, &listen_a, 2);
  netlink_nest(&nlmsg, NLA_F_NESTED | WGDEVICE_A_PEERS);
  netlink_nest(&nlmsg, NLA_F_NESTED | 0);
  netlink_attr(&nlmsg, WGPEER_A_PUBLIC_KEY, public_b, 32);
  netlink_attr(&nlmsg, WGPEER_A_ENDPOINT, &endpoint_b_v4,
               sizeof(endpoint_b_v4));
  netlink_attr(&nlmsg, WGPEER_A_PERSISTENT_KEEPALIVE_INTERVAL,
               &persistent_keepalives[0], 2);
  netlink_nest(&nlmsg, NLA_F_NESTED | WGPEER_A_ALLOWEDIPS);
  netlink_nest(&nlmsg, NLA_F_NESTED | 0);
  netlink_attr(&nlmsg, WGALLOWEDIP_A_FAMILY, &af_inet, 2);
  netlink_attr(&nlmsg, WGALLOWEDIP_A_IPADDR, &first_half_v4,
               sizeof(first_half_v4));
  netlink_attr(&nlmsg, WGALLOWEDIP_A_CIDR_MASK, &half_cidr, 1);
  netlink_done(&nlmsg);
  netlink_nest(&nlmsg, NLA_F_NESTED | 0);
  netlink_attr(&nlmsg, WGALLOWEDIP_A_FAMILY, &af_inet6, 2);
  netlink_attr(&nlmsg, WGALLOWEDIP_A_IPADDR, &first_half_v6,
               sizeof(first_half_v6));
  netlink_attr(&nlmsg, WGALLOWEDIP_A_CIDR_MASK, &half_cidr, 1);
  netlink_done(&nlmsg);
  netlink_done(&nlmsg);
  netlink_done(&nlmsg);
  netlink_nest(&nlmsg, NLA_F_NESTED | 0);
  netlink_attr(&nlmsg, WGPEER_A_PUBLIC_KEY, public_c, 32);
  netlink_attr(&nlmsg, WGPEER_A_ENDPOINT, &endpoint_c_v6,
               sizeof(endpoint_c_v6));
  netlink_attr(&nlmsg, WGPEER_A_PERSISTENT_KEEPALIVE_INTERVAL,
               &persistent_keepalives[1], 2);
  netlink_nest(&nlmsg, NLA_F_NESTED | WGPEER_A_ALLOWEDIPS);
  netlink_nest(&nlmsg, NLA_F_NESTED | 0);
  netlink_attr(&nlmsg, WGALLOWEDIP_A_FAMILY, &af_inet, 2);
  netlink_attr(&nlmsg, WGALLOWEDIP_A_IPADDR, &second_half_v4,
               sizeof(second_half_v4));
  netlink_attr(&nlmsg, WGALLOWEDIP_A_CIDR_MASK, &half_cidr, 1);
  netlink_done(&nlmsg);
  netlink_nest(&nlmsg, NLA_F_NESTED | 0);
  netlink_attr(&nlmsg, WGALLOWEDIP_A_FAMILY, &af_inet6, 2);
  netlink_attr(&nlmsg, WGALLOWEDIP_A_IPADDR, &second_half_v6,
               sizeof(second_half_v6));
  netlink_attr(&nlmsg, WGALLOWEDIP_A_CIDR_MASK, &half_cidr, 1);
  netlink_done(&nlmsg);
  netlink_done(&nlmsg);
  netlink_done(&nlmsg);
  netlink_done(&nlmsg);
  err = netlink_send(&nlmsg, sock);
  if (err) {
  }
  netlink_init(&nlmsg, id, 0, &genlhdr, sizeof(genlhdr));
  netlink_attr(&nlmsg, WGDEVICE_A_IFNAME, ifname_b, strlen(ifname_b) + 1);
  netlink_attr(&nlmsg, WGDEVICE_A_PRIVATE_KEY, private_b, 32);
  netlink_attr(&nlmsg, WGDEVICE_A_LISTEN_PORT, &listen_b, 2);
  netlink_nest(&nlmsg, NLA_F_NESTED | WGDEVICE_A_PEERS);
  netlink_nest(&nlmsg, NLA_F_NESTED | 0);
  netlink_attr(&nlmsg, WGPEER_A_PUBLIC_KEY, public_a, 32);
  netlink_attr(&nlmsg, WGPEER_A_ENDPOINT, &endpoint_a_v6,
               sizeof(endpoint_a_v6));
  netlink_attr(&nlmsg, WGPEER_A_PERSISTENT_KEEPALIVE_INTERVAL,
               &persistent_keepalives[2], 2);
  netlink_nest(&nlmsg, NLA_F_NESTED | WGPEER_A_ALLOWEDIPS);
  netlink_nest(&nlmsg, NLA_F_NESTED | 0);
  netlink_attr(&nlmsg, WGALLOWEDIP_A_FAMILY, &af_inet, 2);
  netlink_attr(&nlmsg, WGALLOWEDIP_A_IPADDR, &first_half_v4,
               sizeof(first_half_v4));
  netlink_attr(&nlmsg, WGALLOWEDIP_A_CIDR_MASK, &half_cidr, 1);
  netlink_done(&nlmsg);
  netlink_nest(&nlmsg, NLA_F_NESTED | 0);
  netlink_attr(&nlmsg, WGALLOWEDIP_A_FAMILY, &af_inet6, 2);
  netlink_attr(&nlmsg, WGALLOWEDIP_A_IPADDR, &first_half_v6,
               sizeof(first_half_v6));
  netlink_attr(&nlmsg, WGALLOWEDIP_A_CIDR_MASK, &half_cidr, 1);
  netlink_done(&nlmsg);
  netlink_done(&nlmsg);
  netlink_done(&nlmsg);
  netlink_nest(&nlmsg, NLA_F_NESTED | 0);
  netlink_attr(&nlmsg, WGPEER_A_PUBLIC_KEY, public_c, 32);
  netlink_attr(&nlmsg, WGPEER_A_ENDPOINT, &endpoint_c_v4,
               sizeof(endpoint_c_v4));
  netlink_attr(&nlmsg, WGPEER_A_PERSISTENT_KEEPALIVE_INTERVAL,
               &persistent_keepalives[3], 2);
  netlink_nest(&nlmsg, NLA_F_NESTED | WGPEER_A_ALLOWEDIPS);
  netlink_nest(&nlmsg, NLA_F_NESTED | 0);
  netlink_attr(&nlmsg, WGALLOWEDIP_A_FAMILY, &af_inet, 2);
  netlink_attr(&nlmsg, WGALLOWEDIP_A_IPADDR, &second_half_v4,
               sizeof(second_half_v4));
  netlink_attr(&nlmsg, WGALLOWEDIP_A_CIDR_MASK, &half_cidr, 1);
  netlink_done(&nlmsg);
  netlink_nest(&nlmsg, NLA_F_NESTED | 0);
  netlink_attr(&nlmsg, WGALLOWEDIP_A_FAMILY, &af_inet6, 2);
  netlink_attr(&nlmsg, WGALLOWEDIP_A_IPADDR, &second_half_v6,
               sizeof(second_half_v6));
  netlink_attr(&nlmsg, WGALLOWEDIP_A_CIDR_MASK, &half_cidr, 1);
  netlink_done(&nlmsg);
  netlink_done(&nlmsg);
  netlink_done(&nlmsg);
  netlink_done(&nlmsg);
  err = netlink_send(&nlmsg, sock);
  if (err) {
  }
  netlink_init(&nlmsg, id, 0, &genlhdr, sizeof(genlhdr));
  netlink_attr(&nlmsg, WGDEVICE_A_IFNAME, ifname_c, strlen(ifname_c) + 1);
  netlink_attr(&nlmsg, WGDEVICE_A_PRIVATE_KEY, private_c, 32);
  netlink_attr(&nlmsg, WGDEVICE_A_LISTEN_PORT, &listen_c, 2);
  netlink_nest(&nlmsg, NLA_F_NESTED | WGDEVICE_A_PEERS);
  netlink_nest(&nlmsg, NLA_F_NESTED | 0);
  netlink_attr(&nlmsg, WGPEER_A_PUBLIC_KEY, public_a, 32);
  netlink_attr(&nlmsg, WGPEER_A_ENDPOINT, &endpoint_a_v6,
               sizeof(endpoint_a_v6));
  netlink_attr(&nlmsg, WGPEER_A_PERSISTENT_KEEPALIVE_INTERVAL,
               &persistent_keepalives[4], 2);
  netlink_nest(&nlmsg, NLA_F_NESTED | WGPEER_A_ALLOWEDIPS);
  netlink_nest(&nlmsg, NLA_F_NESTED | 0);
  netlink_attr(&nlmsg, WGALLOWEDIP_A_FAMILY, &af_inet, 2);
  netlink_attr(&nlmsg, WGALLOWEDIP_A_IPADDR, &first_half_v4,
               sizeof(first_half_v4));
  netlink_attr(&nlmsg, WGALLOWEDIP_A_CIDR_MASK, &half_cidr, 1);
  netlink_done(&nlmsg);
  netlink_nest(&nlmsg, NLA_F_NESTED | 0);
  netlink_attr(&nlmsg, WGALLOWEDIP_A_FAMILY, &af_inet6, 2);
  netlink_attr(&nlmsg, WGALLOWEDIP_A_IPADDR, &first_half_v6,
               sizeof(first_half_v6));
  netlink_attr(&nlmsg, WGALLOWEDIP_A_CIDR_MASK, &half_cidr, 1);
  netlink_done(&nlmsg);
  netlink_done(&nlmsg);
  netlink_done(&nlmsg);
  netlink_nest(&nlmsg, NLA_F_NESTED | 0);
  netlink_attr(&nlmsg, WGPEER_A_PUBLIC_KEY, public_b, 32);
  netlink_attr(&nlmsg, WGPEER_A_ENDPOINT, &endpoint_b_v4,
               sizeof(endpoint_b_v4));
  netlink_attr(&nlmsg, WGPEER_A_PERSISTENT_KEEPALIVE_INTERVAL,
               &persistent_keepalives[5], 2);
  netlink_nest(&nlmsg, NLA_F_NESTED | WGPEER_A_ALLOWEDIPS);
  netlink_nest(&nlmsg, NLA_F_NESTED | 0);
  netlink_attr(&nlmsg, WGALLOWEDIP_A_FAMILY, &af_inet, 2);
  netlink_attr(&nlmsg, WGALLOWEDIP_A_IPADDR, &second_half_v4,
               sizeof(second_half_v4));
  netlink_attr(&nlmsg, WGALLOWEDIP_A_CIDR_MASK, &half_cidr, 1);
  netlink_done(&nlmsg);
  netlink_nest(&nlmsg, NLA_F_NESTED | 0);
  netlink_attr(&nlmsg, WGALLOWEDIP_A_FAMILY, &af_inet6, 2);
  netlink_attr(&nlmsg, WGALLOWEDIP_A_IPADDR, &second_half_v6,
               sizeof(second_half_v6));
  netlink_attr(&nlmsg, WGALLOWEDIP_A_CIDR_MASK, &half_cidr, 1);
  netlink_done(&nlmsg);
  netlink_done(&nlmsg);
  netlink_done(&nlmsg);
  netlink_done(&nlmsg);
  err = netlink_send(&nlmsg, sock);
  if (err) {
  }

error:
  close(sock);
}
static void initialize_netdevices(void)
{
  char netdevsim[16];
  sprintf(netdevsim, "netdevsim%d", (int)procid);
  struct {
    const char* type;
    const char* dev;
  } devtypes[] = {
      {"ip6gretap", "ip6gretap0"}, {"bridge", "bridge0"},
      {"vcan", "vcan0"},           {"bond", "bond0"},
      {"team", "team0"},           {"dummy", "dummy0"},
      {"nlmon", "nlmon0"},         {"caif", "caif0"},
      {"batadv", "batadv0"},       {"vxcan", "vxcan1"},
      {"netdevsim", netdevsim},    {"veth", 0},
      {"xfrm", "xfrm0"},           {"wireguard", "wg0"},
      {"wireguard", "wg1"},        {"wireguard", "wg2"},
  };
  const char* devmasters[] = {"bridge", "bond", "team", "batadv"};
  struct {
    const char* name;
    int macsize;
    bool noipv6;
  } devices[] = {
      {"lo", ETH_ALEN},
      {"sit0", 0},
      {"bridge0", ETH_ALEN},
      {"vcan0", 0, true},
      {"tunl0", 0},
      {"gre0", 0},
      {"gretap0", ETH_ALEN},
      {"ip_vti0", 0},
      {"ip6_vti0", 0},
      {"ip6tnl0", 0},
      {"ip6gre0", 0},
      {"ip6gretap0", ETH_ALEN},
      {"erspan0", ETH_ALEN},
      {"bond0", ETH_ALEN},
      {"veth0", ETH_ALEN},
      {"veth1", ETH_ALEN},
      {"team0", ETH_ALEN},
      {"veth0_to_bridge", ETH_ALEN},
      {"veth1_to_bridge", ETH_ALEN},
      {"veth0_to_bond", ETH_ALEN},
      {"veth1_to_bond", ETH_ALEN},
      {"veth0_to_team", ETH_ALEN},
      {"veth1_to_team", ETH_ALEN},
      {"veth0_to_hsr", ETH_ALEN},
      {"veth1_to_hsr", ETH_ALEN},
      {"hsr0", 0},
      {"dummy0", ETH_ALEN},
      {"nlmon0", 0},
      {"vxcan0", 0, true},
      {"vxcan1", 0, true},
      {"caif0", ETH_ALEN},
      {"batadv0", ETH_ALEN},
      {netdevsim, ETH_ALEN},
      {"xfrm0", ETH_ALEN},
      {"veth0_virt_wifi", ETH_ALEN},
      {"veth1_virt_wifi", ETH_ALEN},
      {"virt_wifi0", ETH_ALEN},
      {"veth0_vlan", ETH_ALEN},
      {"veth1_vlan", ETH_ALEN},
      {"vlan0", ETH_ALEN},
      {"vlan1", ETH_ALEN},
      {"macvlan0", ETH_ALEN},
      {"macvlan1", ETH_ALEN},
      {"ipvlan0", ETH_ALEN},
      {"ipvlan1", ETH_ALEN},
      {"veth0_macvtap", ETH_ALEN},
      {"veth1_macvtap", ETH_ALEN},
      {"macvtap0", ETH_ALEN},
      {"macsec0", ETH_ALEN},
      {"veth0_to_batadv", ETH_ALEN},
      {"veth1_to_batadv", ETH_ALEN},
      {"batadv_slave_0", ETH_ALEN},
      {"batadv_slave_1", ETH_ALEN},
      {"geneve0", ETH_ALEN},
      {"geneve1", ETH_ALEN},
      {"wg0", 0},
      {"wg1", 0},
      {"wg2", 0},
  };
  int sock = socket(AF_NETLINK, SOCK_RAW, NETLINK_ROUTE);
  if (sock == -1)
    exit(1);
  unsigned i;
  for (i = 0; i < sizeof(devtypes) / sizeof(devtypes[0]); i++)
    netlink_add_device(&nlmsg, sock, devtypes[i].type, devtypes[i].dev);
  for (i = 0; i < sizeof(devmasters) / (sizeof(devmasters[0])); i++) {
    char master[32], slave0[32], veth0[32], slave1[32], veth1[32];
    sprintf(slave0, "%s_slave_0", devmasters[i]);
    sprintf(veth0, "veth0_to_%s", devmasters[i]);
    netlink_add_veth(&nlmsg, sock, slave0, veth0);
    sprintf(slave1, "%s_slave_1", devmasters[i]);
    sprintf(veth1, "veth1_to_%s", devmasters[i]);
    netlink_add_veth(&nlmsg, sock, slave1, veth1);
    sprintf(master, "%s0", devmasters[i]);
    netlink_device_change(&nlmsg, sock, slave0, false, master, 0, 0, NULL);
    netlink_device_change(&nlmsg, sock, slave1, false, master, 0, 0, NULL);
  }
  netlink_device_change(&nlmsg, sock, "bridge_slave_0", true, 0, 0, 0, NULL);
  netlink_device_change(&nlmsg, sock, "bridge_slave_1", true, 0, 0, 0, NULL);
  netlink_add_veth(&nlmsg, sock, "hsr_slave_0", "veth0_to_hsr");
  netlink_add_veth(&nlmsg, sock, "hsr_slave_1", "veth1_to_hsr");
  netlink_add_hsr(&nlmsg, sock, "hsr0", "hsr_slave_0", "hsr_slave_1");
  netlink_device_change(&nlmsg, sock, "hsr_slave_0", true, 0, 0, 0, NULL);
  netlink_device_change(&nlmsg, sock, "hsr_slave_1", true, 0, 0, 0, NULL);
  netlink_add_veth(&nlmsg, sock, "veth0_virt_wifi", "veth1_virt_wifi");
  netlink_add_linked(&nlmsg, sock, "virt_wifi", "virt_wifi0",
                     "veth1_virt_wifi");
  netlink_add_veth(&nlmsg, sock, "veth0_vlan", "veth1_vlan");
  netlink_add_vlan(&nlmsg, sock, "vlan0", "veth0_vlan", 0, htons(ETH_P_8021Q));
  netlink_add_vlan(&nlmsg, sock, "vlan1", "veth0_vlan", 1, htons(ETH_P_8021AD));
  netlink_add_macvlan(&nlmsg, sock, "macvlan0", "veth1_vlan");
  netlink_add_macvlan(&nlmsg, sock, "macvlan1", "veth1_vlan");
  netlink_add_ipvlan(&nlmsg, sock, "ipvlan0", "veth0_vlan", IPVLAN_MODE_L2, 0);
  netlink_add_ipvlan(&nlmsg, sock, "ipvlan1", "veth0_vlan", IPVLAN_MODE_L3S,
                     IPVLAN_F_VEPA);
  netlink_add_veth(&nlmsg, sock, "veth0_macvtap", "veth1_macvtap");
  netlink_add_linked(&nlmsg, sock, "macvtap", "macvtap0", "veth0_macvtap");
  netlink_add_linked(&nlmsg, sock, "macsec", "macsec0", "veth1_macvtap");
  char addr[32];
  sprintf(addr, DEV_IPV4, 14 + 10);
  struct in_addr geneve_addr4;
  if (inet_pton(AF_INET, addr, &geneve_addr4) <= 0)
    exit(1);
  struct in6_addr geneve_addr6;
  if (inet_pton(AF_INET6, "fc00::01", &geneve_addr6) <= 0)
    exit(1);
  netlink_add_geneve(&nlmsg, sock, "geneve0", 0, &geneve_addr4, 0);
  netlink_add_geneve(&nlmsg, sock, "geneve1", 1, 0, &geneve_addr6);
  netdevsim_add((int)procid, 4);
  netlink_wireguard_setup();
  for (i = 0; i < sizeof(devices) / (sizeof(devices[0])); i++) {
    char addr[32];
    sprintf(addr, DEV_IPV4, i + 10);
    netlink_add_addr4(&nlmsg, sock, devices[i].name, addr);
    if (!devices[i].noipv6) {
      sprintf(addr, DEV_IPV6, i + 10);
      netlink_add_addr6(&nlmsg, sock, devices[i].name, addr);
    }
    uint64_t macaddr = DEV_MAC + ((i + 10ull) << 40);
    netlink_device_change(&nlmsg, sock, devices[i].name, true, 0, &macaddr,
                          devices[i].macsize, NULL);
  }
  close(sock);
}
static void initialize_netdevices_init(void)
{
  int sock = socket(AF_NETLINK, SOCK_RAW, NETLINK_ROUTE);
  if (sock == -1)
    exit(1);
  struct {
    const char* type;
    int macsize;
    bool noipv6;
    bool noup;
  } devtypes[] = {
      {"nr", 7, true},
      {"rose", 5, true, true},
  };
  unsigned i;
  for (i = 0; i < sizeof(devtypes) / sizeof(devtypes[0]); i++) {
    char dev[32], addr[32];
    sprintf(dev, "%s%d", devtypes[i].type, (int)procid);
    sprintf(addr, "172.30.%d.%d", i, (int)procid + 1);
    netlink_add_addr4(&nlmsg, sock, dev, addr);
    if (!devtypes[i].noipv6) {
      sprintf(addr, "fe88::%02x:%02x", i, (int)procid + 1);
      netlink_add_addr6(&nlmsg, sock, dev, addr);
    }
    int macsize = devtypes[i].macsize;
    uint64_t macaddr = 0xbbbbbb +
                       ((unsigned long long)i << (8 * (macsize - 2))) +
                       (procid << (8 * (macsize - 1)));
    netlink_device_change(&nlmsg, sock, dev, !devtypes[i].noup, 0, &macaddr,
                          macsize, NULL);
  }
  close(sock);
}

static int read_tun(char* data, int size)
{
  if (tunfd < 0)
    return -1;
  int rv = read(tunfd, data, size);
  if (rv < 0) {
    if (errno == EAGAIN)
      return -1;
    if (errno == EBADFD)
      return -1;
    exit(1);
  }
  return rv;
}

static void flush_tun()
{
  char data[1000];
  while (read_tun(&data[0], sizeof(data)) != -1) {
  }
}

#define MAX_FDS 30

static void setup_common()
{
  if (mount(0, "/sys/fs/fuse/connections", "fusectl", 0, 0)) {
  }
}

static void loop();

static void sandbox_common()
{
  prctl(PR_SET_PDEATHSIG, SIGKILL, 0, 0, 0);
  setpgrp();
  setsid();
  struct rlimit rlim;
  rlim.rlim_cur = rlim.rlim_max = (200 << 20);
  setrlimit(RLIMIT_AS, &rlim);
  rlim.rlim_cur = rlim.rlim_max = 32 << 20;
  setrlimit(RLIMIT_MEMLOCK, &rlim);
  rlim.rlim_cur = rlim.rlim_max = 136 << 20;
  setrlimit(RLIMIT_FSIZE, &rlim);
  rlim.rlim_cur = rlim.rlim_max = 1 << 20;
  setrlimit(RLIMIT_STACK, &rlim);
  rlim.rlim_cur = rlim.rlim_max = 0;
  setrlimit(RLIMIT_CORE, &rlim);
  rlim.rlim_cur = rlim.rlim_max = 256;
  setrlimit(RLIMIT_NOFILE, &rlim);
  if (unshare(CLONE_NEWNS)) {
  }
  if (unshare(CLONE_NEWIPC)) {
  }
  if (unshare(0x02000000)) {
  }
  if (unshare(CLONE_NEWUTS)) {
  }
  if (unshare(CLONE_SYSVSEM)) {
  }
  typedef struct {
    const char* name;
    const char* value;
  } sysctl_t;
  static const sysctl_t sysctls[] = {
      {"/proc/sys/kernel/shmmax", "16777216"},
      {"/proc/sys/kernel/shmall", "536870912"},
      {"/proc/sys/kernel/shmmni", "1024"},
      {"/proc/sys/kernel/msgmax", "8192"},
      {"/proc/sys/kernel/msgmni", "1024"},
      {"/proc/sys/kernel/msgmnb", "1024"},
      {"/proc/sys/kernel/sem", "1024 1048576 500 1024"},
  };
  unsigned i;
  for (i = 0; i < sizeof(sysctls) / sizeof(sysctls[0]); i++)
    write_file(sysctls[i].name, sysctls[i].value);
}

int wait_for_loop(int pid)
{
  if (pid < 0)
    exit(1);
  int status = 0;
  while (waitpid(-1, &status, __WALL) != pid) {
  }
  return WEXITSTATUS(status);
}

static void drop_caps(void)
{
  struct __user_cap_header_struct cap_hdr = {};
  struct __user_cap_data_struct cap_data[2] = {};
  cap_hdr.version = _LINUX_CAPABILITY_VERSION_3;
  cap_hdr.pid = getpid();
  if (syscall(SYS_capget, &cap_hdr, &cap_data))
    exit(1);
  const int drop = (1 << CAP_SYS_PTRACE) | (1 << CAP_SYS_NICE);
  cap_data[0].effective &= ~drop;
  cap_data[0].permitted &= ~drop;
  cap_data[0].inheritable &= ~drop;
  if (syscall(SYS_capset, &cap_hdr, &cap_data))
    exit(1);
}

static int do_sandbox_none(void)
{
  int pid = fork();
  if (pid != 0)
    return wait_for_loop(pid);
  setup_common();
  sandbox_common();
  drop_caps();
  initialize_netdevices_init();
  if (unshare(CLONE_NEWNET)) {
  }
  initialize_tun();
  initialize_netdevices();
  loop();
  exit(1);
}

static void kill_and_wait(int pid, int* status)
{
  kill(-pid, SIGKILL);
  kill(pid, SIGKILL);
  int i;
  for (i = 0; i < 100; i++) {
    if (waitpid(-1, status, WNOHANG | __WALL) == pid)
      return;
    usleep(1000);
  }
  DIR* dir = opendir("/sys/fs/fuse/connections");
  if (dir) {
    for (;;) {
      struct dirent* ent = readdir(dir);
      if (!ent)
        break;
      if (strcmp(ent->d_name, ".") == 0 || strcmp(ent->d_name, "..") == 0)
        continue;
      char abort[300];
      snprintf(abort, sizeof(abort), "/sys/fs/fuse/connections/%s/abort",
               ent->d_name);
      int fd = open(abort, O_WRONLY);
      if (fd == -1) {
        continue;
      }
      if (write(fd, abort, 1) < 0) {
      }
      close(fd);
    }
    closedir(dir);
  } else {
  }
  while (waitpid(-1, status, __WALL) != pid) {
  }
}

static void setup_test()
{
  prctl(PR_SET_PDEATHSIG, SIGKILL, 0, 0, 0);
  setpgrp();
  write_file("/proc/self/oom_score_adj", "1000");
  flush_tun();
}

static void close_fds()
{
  int fd;
  for (fd = 3; fd < MAX_FDS; fd++)
    close(fd);
}

static void execute_one(void);

#define WAIT_FLAGS __WALL

static void loop(void)
{
  int iter;
  for (iter = 0;; iter++) {
    int pid = fork();
    if (pid < 0)
      exit(1);
    if (pid == 0) {
      setup_test();
      execute_one();
      close_fds();
      exit(0);
    }
    int status = 0;
    uint64_t start = current_time_ms();
    for (;;) {
      if (waitpid(-1, &status, WNOHANG | WAIT_FLAGS) == pid)
        break;
      sleep_ms(1);
      if (current_time_ms() - start < 5 * 1000)
        continue;
      kill_and_wait(pid, &status);
      break;
    }
  }
}

uint64_t r[5] = {0xffffffffffffffff, 0xffffffffffffffff, 0x0,
                 0xffffffffffffffff, 0xffffffffffffffff};

void execute_one(void)
{
  intptr_t res = 0;
  res = syscall(__NR_socket, 0x10ul, 3ul, 0ul);
  if (res != -1)
    r[0] = res;
  res = syscall(__NR_socket, 0x10ul, 3ul, 0xcul);
  if (res != -1)
    r[1] = res;
  memcpy((void*)0x200000c0, "team0\000\000\000\000\000\000\000\000\000\000\000",
         16);
  *(uint32_t*)0x200000d0 = 0;
  res = syscall(__NR_ioctl, r[1], 0x8933ul, 0x200000c0ul);
  if (res != -1)
    r[2] = *(uint32_t*)0x200000d0;
  *(uint64_t*)0x20000000 = 0;
  *(uint32_t*)0x20000008 = 0;
  *(uint64_t*)0x20000010 = 0x20000100;
  *(uint64_t*)0x20000100 = 0x200001c0;
  *(uint32_t*)0x200001c0 = 0x58;
  *(uint16_t*)0x200001c4 = 0x10;
  *(uint16_t*)0x200001c6 = 0x401;
  *(uint32_t*)0x200001c8 = 0;
  *(uint32_t*)0x200001cc = 0;
  *(uint8_t*)0x200001d0 = 0;
  *(uint8_t*)0x200001d1 = 0;
  *(uint16_t*)0x200001d2 = 0;
  *(uint32_t*)0x200001d4 = 0;
  *(uint32_t*)0x200001d8 = 0;
  *(uint32_t*)0x200001dc = 0;
  *(uint16_t*)0x200001e0 = 0x30;
  STORE_BY_BITMASK(uint16_t, , 0x200001e2, 0x12, 0, 14);
  STORE_BY_BITMASK(uint16_t, , 0x200001e3, 0, 6, 1);
  STORE_BY_BITMASK(uint16_t, , 0x200001e3, 1, 7, 1);
  *(uint16_t*)0x200001e4 = 8;
  *(uint16_t*)0x200001e6 = 1;
  memcpy((void*)0x200001e8, "sit\000", 4);
  *(uint16_t*)0x200001ec = 0x24;
  STORE_BY_BITMASK(uint16_t, , 0x200001ee, 2, 0, 14);
  STORE_BY_BITMASK(uint16_t, , 0x200001ef, 0, 6, 1);
  STORE_BY_BITMASK(uint16_t, , 0x200001ef, 1, 7, 1);
  *(uint16_t*)0x200001f0 = 5;
  *(uint16_t*)0x200001f2 = 0xa;
  *(uint8_t*)0x200001f4 = 1;
  *(uint16_t*)0x200001f8 = 8;
  *(uint16_t*)0x200001fa = 2;
  *(uint8_t*)0x200001fc = 0xac;
  *(uint8_t*)0x200001fd = 0x14;
  *(uint8_t*)0x200001fe = 0x14;
  *(uint8_t*)0x200001ff = 0xaa;
  *(uint16_t*)0x20000200 = 6;
  *(uint16_t*)0x20000202 = 0xd;
  *(uint16_t*)0x20000204 = 4;
  *(uint16_t*)0x20000208 = 6;
  *(uint16_t*)0x2000020a = 0x12;
  *(uint16_t*)0x2000020c = htobe16(0x4e23);
  *(uint16_t*)0x20000210 = 8;
  *(uint16_t*)0x20000212 = 0xa;
  *(uint32_t*)0x20000214 = r[2];
  *(uint64_t*)0x20000108 = 0x58;
  *(uint64_t*)0x20000018 = 1;
  *(uint64_t*)0x20000020 = 0;
  *(uint64_t*)0x20000028 = 0;
  *(uint32_t*)0x20000030 = 0;
  syscall(__NR_sendmsg, r[0], 0x20000000ul, 0ul);
  res = syscall(__NR_socket, 0x10ul, 3ul, 0ul);
  if (res != -1)
    r[3] = res;
  *(uint64_t*)0x20000140 = 0;
  *(uint32_t*)0x20000148 = 0;
  *(uint64_t*)0x20000150 = 0x20000200;
  *(uint64_t*)0x20000200 = 0x200000c0;
  memcpy((void*)0x200000c0,
         "\x68\x00\x00\x00\x10\x00\x01\x08\x00\x00\x00\x00\x00\x00\x00\x00\x00"
         "\x00\x00\x00",
         20);
  *(uint32_t*)0x200000d4 = 0;
  memcpy((void*)0x200000d8,
         "\x00\x00\x00\x00\x04\x00\x00\x00\x14\x00\x1a\x80\x10\x00\x02\x80\x0c"
         "\x00\x01\x80\x08\x00\x04\x00\x00\x00\x00\x00\x08\x00\x1b\x00\x00\x00"
         "\x00\x00\x08\x00\x29\x00\x00\x00\x00\x00\x14\x00\x14\x00\x62\x6f\x6e"
         "\x64\x5f\x73\x6c\x61\x76\x65\x5f\x30\x00\x00\x00\x00\x08\x00\x0a\x00",
         68);
  *(uint32_t*)0x2000011c = 0;
  memcpy((void*)0x20000120, "\000\000\000\000\000\000\000\000", 8);
  *(uint64_t*)0x20000208 = 0x68;
  *(uint64_t*)0x20000158 = 1;
  *(uint64_t*)0x20000160 = 0;
  *(uint64_t*)0x20000168 = 0;
  *(uint32_t*)0x20000170 = 0;
  syscall(__NR_sendmsg, r[3], 0x20000140ul, 0x84ul);
  res = syscall(__NR_socket, 0x10ul, 2ul, 0ul);
  if (res != -1)
    r[4] = res;
  *(uint64_t*)0x20001640 = 0;
  *(uint32_t*)0x20001648 = 0;
  *(uint64_t*)0x20001650 = 0x20000140;
  *(uint64_t*)0x20000140 = 0x20001600;
  memcpy((void*)0x20001600,
         "\x2e\x00\x00\x00\x10\x00\x81\x88\x04\x0f\x80\xec\xdb\x4c\xb9\xcc\xa7"
         "\x48\x0e\xf4\x3c\x00\x00\x00\xe3\xbd\x6e\xfb\x44\x00\x09\x00\x0e\x00"
         "\x0a\x00\x10\x00\x00\x00\x00\x80\x00\x00\x12\x01",
         46);
  *(uint64_t*)0x20000148 = 0x2e;
  *(uint64_t*)0x20001658 = 1;
  *(uint64_t*)0x20001660 = 0;
  *(uint64_t*)0x20001668 = 0;
  *(uint32_t*)0x20001670 = 0;
  syscall(__NR_sendmsg, r[4], 0x20001640ul, 0ul);
}
int main(void)
{
  syscall(__NR_mmap, 0x20000000ul, 0x1000000ul, 3ul, 0x32ul, -1, 0);
  do_sandbox_none();
  return 0;
}


^ permalink raw reply	[flat|nested] 8+ messages in thread

* Re: [PATCH] net: check for dev pointer being NULL in dev_hard_header() to avoid GPF
  2022-12-01 20:10     ` George Kennedy
@ 2022-12-02  4:11       ` Eric Dumazet
  2022-12-06  1:10         ` George Kennedy
  0 siblings, 1 reply; 8+ messages in thread
From: Eric Dumazet @ 2022-12-02  4:11 UTC (permalink / raw)
  To: George Kennedy
  Cc: Pavan Chebbi, davem, kuba, pabeni, netdev, linux-kernel, bpf,
	harshit.m.mogalapalli

On Thu, Dec 1, 2022 at 9:44 PM George Kennedy <george.kennedy@oracle.com> wrote:
>
>
>
> On 12/1/2022 2:25 PM, Eric Dumazet wrote:
> > On Thu, Dec 1, 2022 at 2:16 PM Pavan Chebbi <pavan.chebbi@broadcom.com> wrote:
> >> On Wed, Nov 30, 2022 at 7:43 PM George Kennedy
> >> <george.kennedy@oracle.com> wrote:
> >>> The dev pointer can be NULL in dev_hard_header(). Add check for dev being
> >>> NULL in dev_hard_header() to avoid GPF.
> >>>
> >>> general protection fault, probably for non-canonical address
> >>>      0xdffffc0000000046: 0000 [#1] PREEMPT SMP KASAN NOPTI
> >>> KASAN: null-ptr-deref in range [0x0000000000000230-0x0000000000000237]
> >>> CPU: 1 PID: 45 Comm: kworker/1:1 Not tainted 6.1.0-rc7+ #2
> >>> Hardware name: Red Hat KVM, BIOS 1.15.0-2.module+el8.6.0+20659+3dcf7c70
> >>> Workqueue: mld mld_ifc_work
> >>> RIP: 0010:macvlan_hard_header (./include/linux/netdevice.h:3057
> >>>      (discriminator 4) drivers/net/macvlan.c:594 (discriminator 4))
> >>> RSP: 0018:ffff888103d377d0 EFLAGS: 00010212
> >>> RAX: dffffc0000000000 RBX: ffff88801cf1a000 RCX: 0000000000000000
> >>> RDX: 0000000000000046 RSI: 0000000000000000 RDI: 0000000000000230
> >>> RBP: ffff88801e8ef328 R08: 0000000000000000 R09: 0000000000000060
> >>> R10: 0000000000000000 R11: 0000000000000000 R12: ffff88801f0497c0
> >>> R13: 0000000000000000 R14: ffff888045187c98 R15: 0000000000000060
> >>> FS:  0000000000000000(0000) GS:ffff888106c80000(0000)
> >>>      knlGS:0000000000000000
> >>> CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
> >>> CR2: 00007fbf3f1c1840 CR3: 0000000014e36000 CR4: 00000000000006e0
> >>> Call Trace:
> >>>   <TASK>
> >>> neigh_connected_output (./include/linux/netdevice.h:3060
> >>>      net/core/neighbour.c:1595)
> >>> ip6_finish_output2 (./include/net/neighbour.h:546
> >>>      net/ipv6/ip6_output.c:134)
> >>> ip6_finish_output (net/ipv6/ip6_output.c:195 net/ipv6/ip6_output.c:206)
> >>> ip6_output (./include/linux/netfilter.h:291 net/ipv6/ip6_output.c:227)
> >>> NF_HOOK.constprop.0 (./include/net/dst.h:445
> >>>      ./include/linux/netfilter.h:302)
> >>> mld_sendpack (net/ipv6/mcast.c:1824)
> >>> mld_send_cr (net/ipv6/mcast.c:2122)
> >>> mld_ifc_work (net/ipv6/mcast.c:2655)
> >>> process_one_work (kernel/workqueue.c:2294)
> >>> worker_thread (./include/linux/list.h:292 kernel/workqueue.c:2437)
> >>> kthread (kernel/kthread.c:376)
> >>> ret_from_fork (arch/x86/entry/entry_64.S:312)
> >>>   </TASK>
> >>> Modules linked in:
> >>> Dumping ftrace buffer:
> >>>     (ftrace buffer empty)
> >>> ---[ end trace 0000000000000000 ]---
> >>>
> >>> Fixes: 0c4e85813d0a ("[NET]: Wrap netdevice hardware header creation.")
> >>> Reported-by: syzkaller <syzkaller@googlegroups.com>
> >>> Signed-off-by: George Kennedy <george.kennedy@oracle.com>
> >>> ---
> >>>   include/linux/netdevice.h | 2 +-
> >>>   1 file changed, 1 insertion(+), 1 deletion(-)
> >>>
> >>> diff --git a/include/linux/netdevice.h b/include/linux/netdevice.h
> >>> index eddf8ee270e7..9b25a6301fa5 100644
> >>> --- a/include/linux/netdevice.h
> >>> +++ b/include/linux/netdevice.h
> >>> @@ -3054,7 +3054,7 @@ static inline int dev_hard_header(struct sk_buff *skb, struct net_device *dev,
> >>>                                    const void *daddr, const void *saddr,
> >>>                                    unsigned int len)
> >>>   {
> >>> -       if (!dev->header_ops || !dev->header_ops->create)
> >>> +       if (!dev || !dev->header_ops || !dev->header_ops->create)
> > Do  you have a repro ?
> See syzkaller repros attached.
>
> > This patch will not prevent a crash later I think.
>
> The repro ran overnight without failure with the patch applied.

Yes, but the patch is hiding a potential bug that might show up with
other 'repros'



>
> >
> > Please fix the root cause, thanks !
>
> Will try.

Thanks, having a repro definitely should help to find the real bug.

I took a look at macvlan , and could not see how vlan->lowerdev  could
be NULL in the first place.

>
> Thanks,
> George
> >
> >>>                  return 0;
> >> net_device being NULL during eth header construction? seems like a
> >> more serious issue?
> >> If it indeed is a genuine scenario I think a better description is needed...
> >>
> >>>          return dev->header_ops->create(skb, dev, type, daddr, saddr, len);
> >>> --
> >>> 2.31.1
> >>>

^ permalink raw reply	[flat|nested] 8+ messages in thread

* Re: [PATCH] net: check for dev pointer being NULL in dev_hard_header() to avoid GPF
  2022-12-02  4:11       ` Eric Dumazet
@ 2022-12-06  1:10         ` George Kennedy
  2022-12-06  3:21           ` Eric Dumazet
  0 siblings, 1 reply; 8+ messages in thread
From: George Kennedy @ 2022-12-06  1:10 UTC (permalink / raw)
  To: Eric Dumazet
  Cc: Pavan Chebbi, davem, kuba, pabeni, netdev, linux-kernel, bpf,
	harshit.m.mogalapalli

Hi Eric,

More info...

On 12/1/2022 11:11 PM, Eric Dumazet wrote:
> On Thu, Dec 1, 2022 at 9:44 PM George Kennedy <george.kennedy@oracle.com> wrote:
>>
>>
>> On 12/1/2022 2:25 PM, Eric Dumazet wrote:
>>> On Thu, Dec 1, 2022 at 2:16 PM Pavan Chebbi <pavan.chebbi@broadcom.com> wrote:
>>>> On Wed, Nov 30, 2022 at 7:43 PM George Kennedy
>>>> <george.kennedy@oracle.com> wrote:
>>>>> The dev pointer can be NULL in dev_hard_header(). Add check for dev being
>>>>> NULL in dev_hard_header() to avoid GPF.
>>>>>
>>>>> general protection fault, probably for non-canonical address
>>>>>       0xdffffc0000000046: 0000 [#1] PREEMPT SMP KASAN NOPTI
>>>>> KASAN: null-ptr-deref in range [0x0000000000000230-0x0000000000000237]
>>>>> CPU: 1 PID: 45 Comm: kworker/1:1 Not tainted 6.1.0-rc7+ #2
>>>>> Hardware name: Red Hat KVM, BIOS 1.15.0-2.module+el8.6.0+20659+3dcf7c70
>>>>> Workqueue: mld mld_ifc_work
>>>>> RIP: 0010:macvlan_hard_header (./include/linux/netdevice.h:3057
>>>>>       (discriminator 4) drivers/net/macvlan.c:594 (discriminator 4))
>>>>> RSP: 0018:ffff888103d377d0 EFLAGS: 00010212
>>>>> RAX: dffffc0000000000 RBX: ffff88801cf1a000 RCX: 0000000000000000
>>>>> RDX: 0000000000000046 RSI: 0000000000000000 RDI: 0000000000000230
>>>>> RBP: ffff88801e8ef328 R08: 0000000000000000 R09: 0000000000000060
>>>>> R10: 0000000000000000 R11: 0000000000000000 R12: ffff88801f0497c0
>>>>> R13: 0000000000000000 R14: ffff888045187c98 R15: 0000000000000060
>>>>> FS:  0000000000000000(0000) GS:ffff888106c80000(0000)
>>>>>       knlGS:0000000000000000
>>>>> CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
>>>>> CR2: 00007fbf3f1c1840 CR3: 0000000014e36000 CR4: 00000000000006e0
>>>>> Call Trace:
>>>>>    <TASK>
>>>>> neigh_connected_output (./include/linux/netdevice.h:3060
>>>>>       net/core/neighbour.c:1595)
>>>>> ip6_finish_output2 (./include/net/neighbour.h:546
>>>>>       net/ipv6/ip6_output.c:134)
>>>>> ip6_finish_output (net/ipv6/ip6_output.c:195 net/ipv6/ip6_output.c:206)
>>>>> ip6_output (./include/linux/netfilter.h:291 net/ipv6/ip6_output.c:227)
>>>>> NF_HOOK.constprop.0 (./include/net/dst.h:445
>>>>>       ./include/linux/netfilter.h:302)
>>>>> mld_sendpack (net/ipv6/mcast.c:1824)
>>>>> mld_send_cr (net/ipv6/mcast.c:2122)
>>>>> mld_ifc_work (net/ipv6/mcast.c:2655)
>>>>> process_one_work (kernel/workqueue.c:2294)
>>>>> worker_thread (./include/linux/list.h:292 kernel/workqueue.c:2437)
>>>>> kthread (kernel/kthread.c:376)
>>>>> ret_from_fork (arch/x86/entry/entry_64.S:312)
>>>>>    </TASK>
>>>>> Modules linked in:
>>>>> Dumping ftrace buffer:
>>>>>      (ftrace buffer empty)
>>>>> ---[ end trace 0000000000000000 ]---
>>>>>
>>>>> Fixes: 0c4e85813d0a ("[NET]: Wrap netdevice hardware header creation.")
>>>>> Reported-by: syzkaller <syzkaller@googlegroups.com>
>>>>> Signed-off-by: George Kennedy <george.kennedy@oracle.com>
>>>>> ---
>>>>>    include/linux/netdevice.h | 2 +-
>>>>>    1 file changed, 1 insertion(+), 1 deletion(-)
>>>>>
>>>>> diff --git a/include/linux/netdevice.h b/include/linux/netdevice.h
>>>>> index eddf8ee270e7..9b25a6301fa5 100644
>>>>> --- a/include/linux/netdevice.h
>>>>> +++ b/include/linux/netdevice.h
>>>>> @@ -3054,7 +3054,7 @@ static inline int dev_hard_header(struct sk_buff *skb, struct net_device *dev,
>>>>>                                     const void *daddr, const void *saddr,
>>>>>                                     unsigned int len)
>>>>>    {
>>>>> -       if (!dev->header_ops || !dev->header_ops->create)
>>>>> +       if (!dev || !dev->header_ops || !dev->header_ops->create)
>>> Do  you have a repro ?
>> See syzkaller repros attached.
>>
>>> This patch will not prevent a crash later I think.
>> The repro ran overnight without failure with the patch applied.
> Yes, but the patch is hiding a potential bug that might show up with
> other 'repros'
The repro fails when these devices are configured (seem like small mtu):

20: vxcan0@vxcan1: <NOARP,UP,LOWER_UP> mtu 72 qdisc noqueue state UP group default qlen 1000
     link/can
     inet 172.20.20.38/24 scope global vxcan0
        valid_lft forever preferred_lft forever
21: vxcan1@vxcan0: <NOARP,UP,LOWER_UP> mtu 72 qdisc noqueue state UP group default qlen 1000
     link/can
     inet 172.20.20.39/24 scope global vxcan1
        valid_lft forever preferred_lft forever


# diff ../config.fail .config
3325c3325
< CONFIG_CAN_VXCAN=y
---
> # CONFIG_CAN_VXCAN is not set

Thanks,
George

>>> Please fix the root cause, thanks !
>> Will try.
> Thanks, having a repro definitely should help to find the real bug.
>
> I took a look at macvlan , and could not see how vlan->lowerdev  could
> be NULL in the first place.
>
>> Thanks,
>> George
>>>>>                   return 0;
>>>> net_device being NULL during eth header construction? seems like a
>>>> more serious issue?
>>>> If it indeed is a genuine scenario I think a better description is needed...
>>>>
>>>>>           return dev->header_ops->create(skb, dev, type, daddr, saddr, len);
>>>>> --
>>>>> 2.31.1
>>>>>


^ permalink raw reply	[flat|nested] 8+ messages in thread

* Re: [PATCH] net: check for dev pointer being NULL in dev_hard_header() to avoid GPF
  2022-12-06  1:10         ` George Kennedy
@ 2022-12-06  3:21           ` Eric Dumazet
  2022-12-12 13:34             ` George Kennedy
  0 siblings, 1 reply; 8+ messages in thread
From: Eric Dumazet @ 2022-12-06  3:21 UTC (permalink / raw)
  To: George Kennedy
  Cc: Pavan Chebbi, davem, kuba, pabeni, netdev, linux-kernel, bpf,
	harshit.m.mogalapalli

On Tue, Dec 6, 2022 at 2:11 AM George Kennedy <george.kennedy@oracle.com> wrote:
>
> Hi Eric,
>
> More info...
>
> On 12/1/2022 11:11 PM, Eric Dumazet wrote:
> > On Thu, Dec 1, 2022 at 9:44 PM George Kennedy <george.kennedy@oracle.com> wrote:
> >>
> >>
> >> On 12/1/2022 2:25 PM, Eric Dumazet wrote:
> >>> On Thu, Dec 1, 2022 at 2:16 PM Pavan Chebbi <pavan.chebbi@broadcom.com> wrote:
> >>>> On Wed, Nov 30, 2022 at 7:43 PM George Kennedy
> >>>> <george.kennedy@oracle.com> wrote:
> >>>>> The dev pointer can be NULL in dev_hard_header(). Add check for dev being
> >>>>> NULL in dev_hard_header() to avoid GPF.
> >>>>>
> >>>>> general protection fault, probably for non-canonical address
> >>>>>       0xdffffc0000000046: 0000 [#1] PREEMPT SMP KASAN NOPTI
> >>>>> KASAN: null-ptr-deref in range [0x0000000000000230-0x0000000000000237]
> >>>>> CPU: 1 PID: 45 Comm: kworker/1:1 Not tainted 6.1.0-rc7+ #2
> >>>>> Hardware name: Red Hat KVM, BIOS 1.15.0-2.module+el8.6.0+20659+3dcf7c70
> >>>>> Workqueue: mld mld_ifc_work
> >>>>> RIP: 0010:macvlan_hard_header (./include/linux/netdevice.h:3057
> >>>>>       (discriminator 4) drivers/net/macvlan.c:594 (discriminator 4))
> >>>>> RSP: 0018:ffff888103d377d0 EFLAGS: 00010212
> >>>>> RAX: dffffc0000000000 RBX: ffff88801cf1a000 RCX: 0000000000000000
> >>>>> RDX: 0000000000000046 RSI: 0000000000000000 RDI: 0000000000000230
> >>>>> RBP: ffff88801e8ef328 R08: 0000000000000000 R09: 0000000000000060
> >>>>> R10: 0000000000000000 R11: 0000000000000000 R12: ffff88801f0497c0
> >>>>> R13: 0000000000000000 R14: ffff888045187c98 R15: 0000000000000060
> >>>>> FS:  0000000000000000(0000) GS:ffff888106c80000(0000)
> >>>>>       knlGS:0000000000000000
> >>>>> CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
> >>>>> CR2: 00007fbf3f1c1840 CR3: 0000000014e36000 CR4: 00000000000006e0
> >>>>> Call Trace:
> >>>>>    <TASK>
> >>>>> neigh_connected_output (./include/linux/netdevice.h:3060
> >>>>>       net/core/neighbour.c:1595)
> >>>>> ip6_finish_output2 (./include/net/neighbour.h:546
> >>>>>       net/ipv6/ip6_output.c:134)
> >>>>> ip6_finish_output (net/ipv6/ip6_output.c:195 net/ipv6/ip6_output.c:206)
> >>>>> ip6_output (./include/linux/netfilter.h:291 net/ipv6/ip6_output.c:227)
> >>>>> NF_HOOK.constprop.0 (./include/net/dst.h:445
> >>>>>       ./include/linux/netfilter.h:302)
> >>>>> mld_sendpack (net/ipv6/mcast.c:1824)
> >>>>> mld_send_cr (net/ipv6/mcast.c:2122)
> >>>>> mld_ifc_work (net/ipv6/mcast.c:2655)
> >>>>> process_one_work (kernel/workqueue.c:2294)
> >>>>> worker_thread (./include/linux/list.h:292 kernel/workqueue.c:2437)
> >>>>> kthread (kernel/kthread.c:376)
> >>>>> ret_from_fork (arch/x86/entry/entry_64.S:312)
> >>>>>    </TASK>
> >>>>> Modules linked in:
> >>>>> Dumping ftrace buffer:
> >>>>>      (ftrace buffer empty)
> >>>>> ---[ end trace 0000000000000000 ]---
> >>>>>
> >>>>> Fixes: 0c4e85813d0a ("[NET]: Wrap netdevice hardware header creation.")
> >>>>> Reported-by: syzkaller <syzkaller@googlegroups.com>
> >>>>> Signed-off-by: George Kennedy <george.kennedy@oracle.com>
> >>>>> ---
> >>>>>    include/linux/netdevice.h | 2 +-
> >>>>>    1 file changed, 1 insertion(+), 1 deletion(-)
> >>>>>
> >>>>> diff --git a/include/linux/netdevice.h b/include/linux/netdevice.h
> >>>>> index eddf8ee270e7..9b25a6301fa5 100644
> >>>>> --- a/include/linux/netdevice.h
> >>>>> +++ b/include/linux/netdevice.h
> >>>>> @@ -3054,7 +3054,7 @@ static inline int dev_hard_header(struct sk_buff *skb, struct net_device *dev,
> >>>>>                                     const void *daddr, const void *saddr,
> >>>>>                                     unsigned int len)
> >>>>>    {
> >>>>> -       if (!dev->header_ops || !dev->header_ops->create)
> >>>>> +       if (!dev || !dev->header_ops || !dev->header_ops->create)
> >>> Do  you have a repro ?
> >> See syzkaller repros attached.
> >>
> >>> This patch will not prevent a crash later I think.
> >> The repro ran overnight without failure with the patch applied.
> > Yes, but the patch is hiding a potential bug that might show up with
> > other 'repros'
> The repro fails when these devices are configured (seem like small mtu):
>
> 20: vxcan0@vxcan1: <NOARP,UP,LOWER_UP> mtu 72 qdisc noqueue state UP group default qlen 1000
>      link/can
>      inet 172.20.20.38/24 scope global vxcan0
>         valid_lft forever preferred_lft forever
> 21: vxcan1@vxcan0: <NOARP,UP,LOWER_UP> mtu 72 qdisc noqueue state UP group default qlen 1000
>      link/can
>      inet 172.20.20.39/24 scope global vxcan1
>         valid_lft forever preferred_lft forever
>
>
> # diff ../config.fail .config
> 3325c3325
> < CONFIG_CAN_VXCAN=y
> ---
> > # CONFIG_CAN_VXCAN is not set
>
> Thanks,
> George

Small MTU has caused numerous issues in the past.

I am pretty sure we miss some READ_ONCE(dev->mtu) and other safety checks.

^ permalink raw reply	[flat|nested] 8+ messages in thread

* Re: [PATCH] net: check for dev pointer being NULL in dev_hard_header() to avoid GPF
  2022-12-06  3:21           ` Eric Dumazet
@ 2022-12-12 13:34             ` George Kennedy
  0 siblings, 0 replies; 8+ messages in thread
From: George Kennedy @ 2022-12-12 13:34 UTC (permalink / raw)
  To: Eric Dumazet
  Cc: Pavan Chebbi, davem, kuba, pabeni, netdev, linux-kernel, bpf,
	harshit.m.mogalapalli

Hi Eric,

On 12/5/2022 10:21 PM, Eric Dumazet wrote:
> On Tue, Dec 6, 2022 at 2:11 AM George Kennedy <george.kennedy@oracle.com> wrote:
>> Hi Eric,
>>
>> More info...
>>
>> On 12/1/2022 11:11 PM, Eric Dumazet wrote:
>>> On Thu, Dec 1, 2022 at 9:44 PM George Kennedy <george.kennedy@oracle.com> wrote:
>>>>
>>>> On 12/1/2022 2:25 PM, Eric Dumazet wrote:
>>>>> On Thu, Dec 1, 2022 at 2:16 PM Pavan Chebbi <pavan.chebbi@broadcom.com> wrote:
>>>>>> On Wed, Nov 30, 2022 at 7:43 PM George Kennedy
>>>>>> <george.kennedy@oracle.com> wrote:
>>>>>>> The dev pointer can be NULL in dev_hard_header(). Add check for dev being
>>>>>>> NULL in dev_hard_header() to avoid GPF.
>>>>>>>
>>>>>>> general protection fault, probably for non-canonical address
>>>>>>>        0xdffffc0000000046: 0000 [#1] PREEMPT SMP KASAN NOPTI
>>>>>>> KASAN: null-ptr-deref in range [0x0000000000000230-0x0000000000000237]
>>>>>>> CPU: 1 PID: 45 Comm: kworker/1:1 Not tainted 6.1.0-rc7+ #2
>>>>>>> Hardware name: Red Hat KVM, BIOS 1.15.0-2.module+el8.6.0+20659+3dcf7c70
>>>>>>> Workqueue: mld mld_ifc_work
>>>>>>> RIP: 0010:macvlan_hard_header (./include/linux/netdevice.h:3057
>>>>>>>        (discriminator 4) drivers/net/macvlan.c:594 (discriminator 4))
>>>>>>> RSP: 0018:ffff888103d377d0 EFLAGS: 00010212
>>>>>>> RAX: dffffc0000000000 RBX: ffff88801cf1a000 RCX: 0000000000000000
>>>>>>> RDX: 0000000000000046 RSI: 0000000000000000 RDI: 0000000000000230
>>>>>>> RBP: ffff88801e8ef328 R08: 0000000000000000 R09: 0000000000000060
>>>>>>> R10: 0000000000000000 R11: 0000000000000000 R12: ffff88801f0497c0
>>>>>>> R13: 0000000000000000 R14: ffff888045187c98 R15: 0000000000000060
>>>>>>> FS:  0000000000000000(0000) GS:ffff888106c80000(0000)
>>>>>>>        knlGS:0000000000000000
>>>>>>> CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
>>>>>>> CR2: 00007fbf3f1c1840 CR3: 0000000014e36000 CR4: 00000000000006e0
>>>>>>> Call Trace:
>>>>>>>     <TASK>
>>>>>>> neigh_connected_output (./include/linux/netdevice.h:3060
>>>>>>>        net/core/neighbour.c:1595)
>>>>>>> ip6_finish_output2 (./include/net/neighbour.h:546
>>>>>>>        net/ipv6/ip6_output.c:134)
>>>>>>> ip6_finish_output (net/ipv6/ip6_output.c:195 net/ipv6/ip6_output.c:206)
>>>>>>> ip6_output (./include/linux/netfilter.h:291 net/ipv6/ip6_output.c:227)
>>>>>>> NF_HOOK.constprop.0 (./include/net/dst.h:445
>>>>>>>        ./include/linux/netfilter.h:302)
>>>>>>> mld_sendpack (net/ipv6/mcast.c:1824)
>>>>>>> mld_send_cr (net/ipv6/mcast.c:2122)
>>>>>>> mld_ifc_work (net/ipv6/mcast.c:2655)
>>>>>>> process_one_work (kernel/workqueue.c:2294)
>>>>>>> worker_thread (./include/linux/list.h:292 kernel/workqueue.c:2437)
>>>>>>> kthread (kernel/kthread.c:376)
>>>>>>> ret_from_fork (arch/x86/entry/entry_64.S:312)
>>>>>>>     </TASK>
>>>>>>> Modules linked in:
>>>>>>> Dumping ftrace buffer:
>>>>>>>       (ftrace buffer empty)
>>>>>>> ---[ end trace 0000000000000000 ]---
>>>>>>>
>>>>>>> Fixes: 0c4e85813d0a ("[NET]: Wrap netdevice hardware header creation.")
>>>>>>> Reported-by: syzkaller <syzkaller@googlegroups.com>
>>>>>>> Signed-off-by: George Kennedy <george.kennedy@oracle.com>
>>>>>>> ---
>>>>>>>     include/linux/netdevice.h | 2 +-
>>>>>>>     1 file changed, 1 insertion(+), 1 deletion(-)
>>>>>>>
>>>>>>> diff --git a/include/linux/netdevice.h b/include/linux/netdevice.h
>>>>>>> index eddf8ee270e7..9b25a6301fa5 100644
>>>>>>> --- a/include/linux/netdevice.h
>>>>>>> +++ b/include/linux/netdevice.h
>>>>>>> @@ -3054,7 +3054,7 @@ static inline int dev_hard_header(struct sk_buff *skb, struct net_device *dev,
>>>>>>>                                      const void *daddr, const void *saddr,
>>>>>>>                                      unsigned int len)
>>>>>>>     {
>>>>>>> -       if (!dev->header_ops || !dev->header_ops->create)
>>>>>>> +       if (!dev || !dev->header_ops || !dev->header_ops->create)
>>>>> Do  you have a repro ?
>>>> See syzkaller repros attached.
>>>>
>>>>> This patch will not prevent a crash later I think.
>>>> The repro ran overnight without failure with the patch applied.
>>> Yes, but the patch is hiding a potential bug that might show up with
>>> other 'repros'
>> The repro fails when these devices are configured (seem like small mtu):
>>
>> 20: vxcan0@vxcan1: <NOARP,UP,LOWER_UP> mtu 72 qdisc noqueue state UP group default qlen 1000
>>       link/can
>>       inet 172.20.20.38/24 scope global vxcan0
>>          valid_lft forever preferred_lft forever
>> 21: vxcan1@vxcan0: <NOARP,UP,LOWER_UP> mtu 72 qdisc noqueue state UP group default qlen 1000
>>       link/can
>>       inet 172.20.20.39/24 scope global vxcan1
>>          valid_lft forever preferred_lft forever
>>
>>
>> # diff ../config.fail .config
>> 3325c3325
>> < CONFIG_CAN_VXCAN=y
>> ---
>>> # CONFIG_CAN_VXCAN is not set
>> Thanks,
>> George
> Small MTU has caused numerous issues in the past.
>
> I am pretty sure we miss some READ_ONCE(dev->mtu) and other safety checks.

I have not been able to find the root-cause of the "vxcan" related GPF 
yet. What I do know is that for the GPF to occur:
1) CONFIG_CAN_VXCAN=y must be set
2) if CONFIG_CAN_VXCAN=y is set, the GPF will not occur if "vxcan" is 
commented out of the C reproducer

C reproducer with "vxcan" commented out (GPF will not occur):

# diff -C 3 repro_macvlan1.c repro_macvlan1_no_vsxcan.c
*** repro_macvlan1.c    2022-12-06 01:03:47.557094544 +0000
--- repro_macvlan1_no_vsxcan.c    2022-12-12 13:15:05.293719169 +0000
***************
*** 884,890 ****
         {"vcan", "vcan0"},           {"bond", "bond0"},
         {"team", "team0"},           {"dummy", "dummy0"},
         {"nlmon", "nlmon0"},         {"caif", "caif0"},
!       {"batadv", "batadv0"},       {"vxcan", "vxcan1"},
         {"netdevsim", netdevsim},    {"veth", 0},
         {"xfrm", "xfrm0"},           {"wireguard", "wg0"},
         {"wireguard", "wg1"},        {"wireguard", "wg2"},
--- 884,893 ----
         {"vcan", "vcan0"},           {"bond", "bond0"},
         {"team", "team0"},           {"dummy", "dummy0"},
         {"nlmon", "nlmon0"},         {"caif", "caif0"},
!       {"batadv", "batadv0"},
! #ifdef VXCAN
!       {"vxcan", "vxcan1"},
! #endif
         {"netdevsim", netdevsim},    {"veth", 0},
         {"xfrm", "xfrm0"},           {"wireguard", "wg0"},
         {"wireguard", "wg1"},        {"wireguard", "wg2"},
***************
*** 923,930 ****
--- 926,935 ----
         {"hsr0", 0},
         {"dummy0", ETH_ALEN},
         {"nlmon0", 0},
+ #ifdef VXCAN
         {"vxcan0", 0, true},
         {"vxcan1", 0, true},
+ #endif
         {"caif0", ETH_ALEN},
         {"batadv0", ETH_ALEN},
         {netdevsim, ETH_ALEN},

I think for now until the vxcan related GPF root-cause is found, the 
"dev NULL check" patch should go in. The "dev NULL check" patch is on 
same line as 2 other NULL checks.

Could you try the original C reproducer with kernel with 
CONFIG_CAN_VXCAN=y set to see if you have any insights as to the GPF 
root-cause?

Thank you,
George



^ permalink raw reply	[flat|nested] 8+ messages in thread

end of thread, other threads:[~2022-12-12 13:34 UTC | newest]

Thread overview: 8+ messages (download: mbox.gz / follow: Atom feed)
-- links below jump to the message on this page --
2022-11-30 14:11 [PATCH] net: check for dev pointer being NULL in dev_hard_header() to avoid GPF George Kennedy
2022-12-01 13:16 ` Pavan Chebbi
2022-12-01 19:25   ` Eric Dumazet
2022-12-01 20:10     ` George Kennedy
2022-12-02  4:11       ` Eric Dumazet
2022-12-06  1:10         ` George Kennedy
2022-12-06  3:21           ` Eric Dumazet
2022-12-12 13:34             ` George Kennedy

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