[PATCH v1 net] udplite: Fix NULL pointer dereference in __sk_mem_raise_allocated().

[PATCH v1 net] udplite: Fix NULL pointer dereference in __sk_mem_raise_allocated().

[Kuniyuki Iwashima]

syzbot reported [0] a null-ptr-deref in sk_get_rmem0() while using
IPPROTO_UDPLITE (0x88):

  14:25:52 executing program 1:
  r0 = socket$inet6(0xa, 0x80002, 0x88)

We had a similar report [1] for probably sk_memory_allocated_add()
in __sk_mem_raise_allocated(), and commit c915fe13cbaa ("udplite: fix
NULL pointer dereference") fixed it by setting .memory_allocated for
udplite_prot and udplitev6_prot.

To fix the variant, we need to set either .sysctl_wmem_offset or
.sysctl_rmem.

Now UDP and UDPLITE share the same value for .memory_allocated, so we
use the same .sysctl_wmem_offset for UDP and UDPLITE.

[0]:
general protection fault, probably for non-canonical address 0xdffffc0000000000: 0000 [#1] PREEMPT SMP KASAN
KASAN: null-ptr-deref in range [0x0000000000000000-0x0000000000000007]
CPU: 0 PID: 6829 Comm: syz-executor.1 Not tainted 6.4.0-rc2-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 04/28/2023
RIP: 0010:sk_get_rmem0 include/net/sock.h:2907 [inline]
RIP: 0010:__sk_mem_raise_allocated+0x806/0x17a0 net/core/sock.c:3006
Code: c1 ea 03 80 3c 02 00 0f 85 23 0f 00 00 48 8b 44 24 08 48 8b 98 38 01 00 00 48 b8 00 00 00 00 00 fc ff df 48 89 da 48 c1 ea 03 <0f> b6 14 02 48 89 d8 83 e0 07 83 c0 03 38 d0 0f 8d 6f 0a 00 00 8b
RSP: 0018:ffffc90005d7f450 EFLAGS: 00010246
RAX: dffffc0000000000 RBX: 0000000000000000 RCX: ffffc90004d92000
RDX: 0000000000000000 RSI: ffffffff88066482 RDI: ffffffff8e2ccbb8
RBP: ffff8880173f7000 R08: 0000000000000005 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000000 R12: 0000000000030000
R13: 0000000000000001 R14: 0000000000000340 R15: 0000000000000001
FS:  0000000000000000(0000) GS:ffff8880b9800000(0063) knlGS:00000000f7f1cb40
CS:  0010 DS: 002b ES: 002b CR0: 0000000080050033
CR2: 000000002e82f000 CR3: 0000000034ff0000 CR4: 00000000003506f0
Call Trace:
 <TASK>
 __sk_mem_schedule+0x6c/0xe0 net/core/sock.c:3077
 udp_rmem_schedule net/ipv4/udp.c:1539 [inline]
 __udp_enqueue_schedule_skb+0x776/0xb30 net/ipv4/udp.c:1581
 __udpv6_queue_rcv_skb net/ipv6/udp.c:666 [inline]
 udpv6_queue_rcv_one_skb+0xc39/0x16c0 net/ipv6/udp.c:775
 udpv6_queue_rcv_skb+0x194/0xa10 net/ipv6/udp.c:793
 __udp6_lib_mcast_deliver net/ipv6/udp.c:906 [inline]
 __udp6_lib_rcv+0x1bda/0x2bd0 net/ipv6/udp.c:1013
 ip6_protocol_deliver_rcu+0x2e7/0x1250 net/ipv6/ip6_input.c:437
 ip6_input_finish+0x150/0x2f0 net/ipv6/ip6_input.c:482
 NF_HOOK include/linux/netfilter.h:303 [inline]
 NF_HOOK include/linux/netfilter.h:297 [inline]
 ip6_input+0xa0/0xd0 net/ipv6/ip6_input.c:491
 ip6_mc_input+0x40b/0xf50 net/ipv6/ip6_input.c:585
 dst_input include/net/dst.h:468 [inline]
 ip6_rcv_finish net/ipv6/ip6_input.c:79 [inline]
 NF_HOOK include/linux/netfilter.h:303 [inline]
 NF_HOOK include/linux/netfilter.h:297 [inline]
 ipv6_rcv+0x250/0x380 net/ipv6/ip6_input.c:309
 __netif_receive_skb_one_core+0x114/0x180 net/core/dev.c:5491
 __netif_receive_skb+0x1f/0x1c0 net/core/dev.c:5605
 netif_receive_skb_internal net/core/dev.c:5691 [inline]
 netif_receive_skb+0x133/0x7a0 net/core/dev.c:5750
 tun_rx_batched+0x4b3/0x7a0 drivers/net/tun.c:1553
 tun_get_user+0x2452/0x39c0 drivers/net/tun.c:1989
 tun_chr_write_iter+0xdf/0x200 drivers/net/tun.c:2035
 call_write_iter include/linux/fs.h:1868 [inline]
 new_sync_write fs/read_write.c:491 [inline]
 vfs_write+0x945/0xd50 fs/read_write.c:584
 ksys_write+0x12b/0x250 fs/read_write.c:637
 do_syscall_32_irqs_on arch/x86/entry/common.c:112 [inline]
 __do_fast_syscall_32+0x65/0xf0 arch/x86/entry/common.c:178
 do_fast_syscall_32+0x33/0x70 arch/x86/entry/common.c:203
 entry_SYSENTER_compat_after_hwframe+0x70/0x82
RIP: 0023:0xf7f21579
Code: b8 01 10 06 03 74 b4 01 10 07 03 74 b0 01 10 08 03 74 d8 01 00 00 00 00 00 00 00 00 00 00 00 00 00 51 52 55 89 e5 0f 34 cd 80 <5d> 5a 59 c3 90 90 90 90 8d b4 26 00 00 00 00 8d b4 26 00 00 00 00
RSP: 002b:00000000f7f1c590 EFLAGS: 00000282 ORIG_RAX: 0000000000000004
RAX: ffffffffffffffda RBX: 00000000000000c8 RCX: 0000000020000040
RDX: 0000000000000083 RSI: 00000000f734e000 RDI: 0000000000000000
RBP: 0000000000000000 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000296 R12: 0000000000000000
R13: 0000000000000000 R14: 0000000000000000 R15: 0000000000000000
 </TASK>
Modules linked in:

Link: https://lore.kernel.org/netdev/CANaxB-yCk8hhP68L4Q2nFOJht8sqgXGGQO2AftpHs0u1xyGG5A@mail.gmail.com/ [1]
Fixes: 850cbaddb52d ("udp: use it's own memory accounting schema")
Reported-by: syzbot+444ca0907e96f7c5e48b@syzkaller.appspotmail.com
Closes: https://syzkaller.appspot.com/bug?extid=444ca0907e96f7c5e48b
Signed-off-by: Kuniyuki Iwashima <kuniyu@amazon.com>
---
 net/ipv4/udplite.c | 2 ++
 net/ipv6/udplite.c | 2 ++
 2 files changed, 4 insertions(+)

diff --git a/net/ipv4/udplite.c b/net/ipv4/udplite.c
index e0c9cc39b81e..56d94d23b9e0 100644
--- a/net/ipv4/udplite.c
+++ b/net/ipv4/udplite.c
@@ -64,6 +64,8 @@ struct proto 	udplite_prot = {
 	.per_cpu_fw_alloc  = &udp_memory_per_cpu_fw_alloc,
 
 	.sysctl_mem	   = sysctl_udp_mem,
+	.sysctl_wmem_offset = offsetof(struct net, ipv4.sysctl_udp_wmem_min),
+	.sysctl_rmem_offset = offsetof(struct net, ipv4.sysctl_udp_rmem_min),
 	.obj_size	   = sizeof(struct udp_sock),
 	.h.udp_table	   = &udplite_table,
 };
diff --git a/net/ipv6/udplite.c b/net/ipv6/udplite.c
index 67eaf3ca14ce..3bab0cc13697 100644
--- a/net/ipv6/udplite.c
+++ b/net/ipv6/udplite.c
@@ -60,6 +60,8 @@ struct proto udplitev6_prot = {
 	.per_cpu_fw_alloc  = &udp_memory_per_cpu_fw_alloc,
 
 	.sysctl_mem	   = sysctl_udp_mem,
+	.sysctl_wmem_offset = offsetof(struct net, ipv4.sysctl_udp_wmem_min),
+	.sysctl_rmem_offset = offsetof(struct net, ipv4.sysctl_udp_rmem_min),
 	.obj_size	   = sizeof(struct udp6_sock),
 	.h.udp_table	   = &udplite_table,
 };
-- 
2.30.2

Re: [PATCH v1 net] udplite: Fix NULL pointer dereference in __sk_mem_raise_allocated().

[Paolo Abeni]

On Tue, 2023-05-23 at 09:33 -0700, Kuniyuki Iwashima wrote:
> syzbot reported [0] a null-ptr-deref in sk_get_rmem0() while using
> IPPROTO_UDPLITE (0x88):
> 
>   14:25:52 executing program 1:
>   r0 = socket$inet6(0xa, 0x80002, 0x88)
> 
> We had a similar report [1] for probably sk_memory_allocated_add()
> in __sk_mem_raise_allocated(), and commit c915fe13cbaa ("udplite: fix
> NULL pointer dereference") fixed it by setting .memory_allocated for
> udplite_prot and udplitev6_prot.
> 
> To fix the variant, we need to set either .sysctl_wmem_offset or
> .sysctl_rmem.
> 
> Now UDP and UDPLITE share the same value for .memory_allocated, so we
> use the same .sysctl_wmem_offset for UDP and UDPLITE.
> 
> [0]:
> general protection fault, probably for non-canonical address 0xdffffc0000000000: 0000 [#1] PREEMPT SMP KASAN
> KASAN: null-ptr-deref in range [0x0000000000000000-0x0000000000000007]
> CPU: 0 PID: 6829 Comm: syz-executor.1 Not tainted 6.4.0-rc2-syzkaller #0
> Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 04/28/2023
> RIP: 0010:sk_get_rmem0 include/net/sock.h:2907 [inline]
> RIP: 0010:__sk_mem_raise_allocated+0x806/0x17a0 net/core/sock.c:3006
> Code: c1 ea 03 80 3c 02 00 0f 85 23 0f 00 00 48 8b 44 24 08 48 8b 98 38 01 00 00 48 b8 00 00 00 00 00 fc ff df 48 89 da 48 c1 ea 03 <0f> b6 14 02 48 89 d8 83 e0 07 83 c0 03 38 d0 0f 8d 6f 0a 00 00 8b
> RSP: 0018:ffffc90005d7f450 EFLAGS: 00010246
> RAX: dffffc0000000000 RBX: 0000000000000000 RCX: ffffc90004d92000
> RDX: 0000000000000000 RSI: ffffffff88066482 RDI: ffffffff8e2ccbb8
> RBP: ffff8880173f7000 R08: 0000000000000005 R09: 0000000000000000
> R10: 0000000000000000 R11: 0000000000000000 R12: 0000000000030000
> R13: 0000000000000001 R14: 0000000000000340 R15: 0000000000000001
> FS:  0000000000000000(0000) GS:ffff8880b9800000(0063) knlGS:00000000f7f1cb40
> CS:  0010 DS: 002b ES: 002b CR0: 0000000080050033
> CR2: 000000002e82f000 CR3: 0000000034ff0000 CR4: 00000000003506f0
> Call Trace:
>  <TASK>
>  __sk_mem_schedule+0x6c/0xe0 net/core/sock.c:3077
>  udp_rmem_schedule net/ipv4/udp.c:1539 [inline]
>  __udp_enqueue_schedule_skb+0x776/0xb30 net/ipv4/udp.c:1581
>  __udpv6_queue_rcv_skb net/ipv6/udp.c:666 [inline]
>  udpv6_queue_rcv_one_skb+0xc39/0x16c0 net/ipv6/udp.c:775
>  udpv6_queue_rcv_skb+0x194/0xa10 net/ipv6/udp.c:793
>  __udp6_lib_mcast_deliver net/ipv6/udp.c:906 [inline]
>  __udp6_lib_rcv+0x1bda/0x2bd0 net/ipv6/udp.c:1013
>  ip6_protocol_deliver_rcu+0x2e7/0x1250 net/ipv6/ip6_input.c:437
>  ip6_input_finish+0x150/0x2f0 net/ipv6/ip6_input.c:482
>  NF_HOOK include/linux/netfilter.h:303 [inline]
>  NF_HOOK include/linux/netfilter.h:297 [inline]
>  ip6_input+0xa0/0xd0 net/ipv6/ip6_input.c:491
>  ip6_mc_input+0x40b/0xf50 net/ipv6/ip6_input.c:585
>  dst_input include/net/dst.h:468 [inline]
>  ip6_rcv_finish net/ipv6/ip6_input.c:79 [inline]
>  NF_HOOK include/linux/netfilter.h:303 [inline]
>  NF_HOOK include/linux/netfilter.h:297 [inline]
>  ipv6_rcv+0x250/0x380 net/ipv6/ip6_input.c:309
>  __netif_receive_skb_one_core+0x114/0x180 net/core/dev.c:5491
>  __netif_receive_skb+0x1f/0x1c0 net/core/dev.c:5605
>  netif_receive_skb_internal net/core/dev.c:5691 [inline]
>  netif_receive_skb+0x133/0x7a0 net/core/dev.c:5750
>  tun_rx_batched+0x4b3/0x7a0 drivers/net/tun.c:1553
>  tun_get_user+0x2452/0x39c0 drivers/net/tun.c:1989
>  tun_chr_write_iter+0xdf/0x200 drivers/net/tun.c:2035
>  call_write_iter include/linux/fs.h:1868 [inline]
>  new_sync_write fs/read_write.c:491 [inline]
>  vfs_write+0x945/0xd50 fs/read_write.c:584
>  ksys_write+0x12b/0x250 fs/read_write.c:637
>  do_syscall_32_irqs_on arch/x86/entry/common.c:112 [inline]
>  __do_fast_syscall_32+0x65/0xf0 arch/x86/entry/common.c:178
>  do_fast_syscall_32+0x33/0x70 arch/x86/entry/common.c:203
>  entry_SYSENTER_compat_after_hwframe+0x70/0x82
> RIP: 0023:0xf7f21579
> Code: b8 01 10 06 03 74 b4 01 10 07 03 74 b0 01 10 08 03 74 d8 01 00 00 00 00 00 00 00 00 00 00 00 00 00 51 52 55 89 e5 0f 34 cd 80 <5d> 5a 59 c3 90 90 90 90 8d b4 26 00 00 00 00 8d b4 26 00 00 00 00
> RSP: 002b:00000000f7f1c590 EFLAGS: 00000282 ORIG_RAX: 0000000000000004
> RAX: ffffffffffffffda RBX: 00000000000000c8 RCX: 0000000020000040
> RDX: 0000000000000083 RSI: 00000000f734e000 RDI: 0000000000000000
> RBP: 0000000000000000 R08: 0000000000000000 R09: 0000000000000000
> R10: 0000000000000000 R11: 0000000000000296 R12: 0000000000000000
> R13: 0000000000000000 R14: 0000000000000000 R15: 0000000000000000
>  </TASK>
> Modules linked in:
> 
> Link: https://lore.kernel.org/netdev/CANaxB-yCk8hhP68L4Q2nFOJht8sqgXGGQO2AftpHs0u1xyGG5A@mail.gmail.com/ [1]
> Fixes: 850cbaddb52d ("udp: use it's own memory accounting schema")

Thanks for addressing this issue!

The patch LGTM. 

Side note: the blamed commit is almost 7y old and the oops should not
that hard to reproduce by a real app using UDP-lite, but only syzkaller
stumbled upon it.

The above looks like a serious hint UDP-lite is not used by anyone
anymore ?!? Perhaps we could consider deprecating and dropping it? It
could simplify the UDP code a bit removing a bunch of conditionals in
fast-path, and that  nowadays would be possibly more relevant?!?

Cheers,

Paolo

Re: [PATCH v1 net] udplite: Fix NULL pointer dereference in __sk_mem_raise_allocated().

[patchwork-bot+netdevbpf]

Hello:

This patch was applied to netdev/net.git (main)
by Paolo Abeni <pabeni@redhat.com>:

On Tue, 23 May 2023 09:33:05 -0700 you wrote:
> syzbot reported [0] a null-ptr-deref in sk_get_rmem0() while using
> IPPROTO_UDPLITE (0x88):
> 
>   14:25:52 executing program 1:
>   r0 = socket$inet6(0xa, 0x80002, 0x88)
> 
> We had a similar report [1] for probably sk_memory_allocated_add()
> in __sk_mem_raise_allocated(), and commit c915fe13cbaa ("udplite: fix
> NULL pointer dereference") fixed it by setting .memory_allocated for
> udplite_prot and udplitev6_prot.
> 
> [...]

Here is the summary with links:
  - [v1,net] udplite: Fix NULL pointer dereference in __sk_mem_raise_allocated().
    https://git.kernel.org/netdev/net/c/ad42a35bdfc6

You are awesome, thank you!
-- 
Deet-doot-dot, I am a bot.
https://korg.docs.kernel.org/patchwork/pwbot.html

Re: [PATCH v1 net] udplite: Fix NULL pointer dereference in __sk_mem_raise_allocated().

[Kuniyuki Iwashima]

From: Paolo Abeni <pabeni@redhat.com>
Date: Thu, 25 May 2023 10:59:09 +0200
> On Tue, 2023-05-23 at 09:33 -0700, Kuniyuki Iwashima wrote:
> > syzbot reported [0] a null-ptr-deref in sk_get_rmem0() while using
> > IPPROTO_UDPLITE (0x88):
> > 
> >   14:25:52 executing program 1:
> >   r0 = socket$inet6(0xa, 0x80002, 0x88)
> > 
> > We had a similar report [1] for probably sk_memory_allocated_add()
> > in __sk_mem_raise_allocated(), and commit c915fe13cbaa ("udplite: fix
> > NULL pointer dereference") fixed it by setting .memory_allocated for
> > udplite_prot and udplitev6_prot.
> > 
> > To fix the variant, we need to set either .sysctl_wmem_offset or
> > .sysctl_rmem.
> > 
> > Now UDP and UDPLITE share the same value for .memory_allocated, so we
> > use the same .sysctl_wmem_offset for UDP and UDPLITE.
> > 
> > [0]:
> > general protection fault, probably for non-canonical address 0xdffffc0000000000: 0000 [#1] PREEMPT SMP KASAN
> > KASAN: null-ptr-deref in range [0x0000000000000000-0x0000000000000007]
> > CPU: 0 PID: 6829 Comm: syz-executor.1 Not tainted 6.4.0-rc2-syzkaller #0
> > Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 04/28/2023
> > RIP: 0010:sk_get_rmem0 include/net/sock.h:2907 [inline]
> > RIP: 0010:__sk_mem_raise_allocated+0x806/0x17a0 net/core/sock.c:3006
> > Code: c1 ea 03 80 3c 02 00 0f 85 23 0f 00 00 48 8b 44 24 08 48 8b 98 38 01 00 00 48 b8 00 00 00 00 00 fc ff df 48 89 da 48 c1 ea 03 <0f> b6 14 02 48 89 d8 83 e0 07 83 c0 03 38 d0 0f 8d 6f 0a 00 00 8b
> > RSP: 0018:ffffc90005d7f450 EFLAGS: 00010246
> > RAX: dffffc0000000000 RBX: 0000000000000000 RCX: ffffc90004d92000
> > RDX: 0000000000000000 RSI: ffffffff88066482 RDI: ffffffff8e2ccbb8
> > RBP: ffff8880173f7000 R08: 0000000000000005 R09: 0000000000000000
> > R10: 0000000000000000 R11: 0000000000000000 R12: 0000000000030000
> > R13: 0000000000000001 R14: 0000000000000340 R15: 0000000000000001
> > FS:  0000000000000000(0000) GS:ffff8880b9800000(0063) knlGS:00000000f7f1cb40
> > CS:  0010 DS: 002b ES: 002b CR0: 0000000080050033
> > CR2: 000000002e82f000 CR3: 0000000034ff0000 CR4: 00000000003506f0
> > Call Trace:
> >  <TASK>
> >  __sk_mem_schedule+0x6c/0xe0 net/core/sock.c:3077
> >  udp_rmem_schedule net/ipv4/udp.c:1539 [inline]
> >  __udp_enqueue_schedule_skb+0x776/0xb30 net/ipv4/udp.c:1581
> >  __udpv6_queue_rcv_skb net/ipv6/udp.c:666 [inline]
> >  udpv6_queue_rcv_one_skb+0xc39/0x16c0 net/ipv6/udp.c:775
> >  udpv6_queue_rcv_skb+0x194/0xa10 net/ipv6/udp.c:793
> >  __udp6_lib_mcast_deliver net/ipv6/udp.c:906 [inline]
> >  __udp6_lib_rcv+0x1bda/0x2bd0 net/ipv6/udp.c:1013
> >  ip6_protocol_deliver_rcu+0x2e7/0x1250 net/ipv6/ip6_input.c:437
> >  ip6_input_finish+0x150/0x2f0 net/ipv6/ip6_input.c:482
> >  NF_HOOK include/linux/netfilter.h:303 [inline]
> >  NF_HOOK include/linux/netfilter.h:297 [inline]
> >  ip6_input+0xa0/0xd0 net/ipv6/ip6_input.c:491
> >  ip6_mc_input+0x40b/0xf50 net/ipv6/ip6_input.c:585
> >  dst_input include/net/dst.h:468 [inline]
> >  ip6_rcv_finish net/ipv6/ip6_input.c:79 [inline]
> >  NF_HOOK include/linux/netfilter.h:303 [inline]
> >  NF_HOOK include/linux/netfilter.h:297 [inline]
> >  ipv6_rcv+0x250/0x380 net/ipv6/ip6_input.c:309
> >  __netif_receive_skb_one_core+0x114/0x180 net/core/dev.c:5491
> >  __netif_receive_skb+0x1f/0x1c0 net/core/dev.c:5605
> >  netif_receive_skb_internal net/core/dev.c:5691 [inline]
> >  netif_receive_skb+0x133/0x7a0 net/core/dev.c:5750
> >  tun_rx_batched+0x4b3/0x7a0 drivers/net/tun.c:1553
> >  tun_get_user+0x2452/0x39c0 drivers/net/tun.c:1989
> >  tun_chr_write_iter+0xdf/0x200 drivers/net/tun.c:2035
> >  call_write_iter include/linux/fs.h:1868 [inline]
> >  new_sync_write fs/read_write.c:491 [inline]
> >  vfs_write+0x945/0xd50 fs/read_write.c:584
> >  ksys_write+0x12b/0x250 fs/read_write.c:637
> >  do_syscall_32_irqs_on arch/x86/entry/common.c:112 [inline]
> >  __do_fast_syscall_32+0x65/0xf0 arch/x86/entry/common.c:178
> >  do_fast_syscall_32+0x33/0x70 arch/x86/entry/common.c:203
> >  entry_SYSENTER_compat_after_hwframe+0x70/0x82
> > RIP: 0023:0xf7f21579
> > Code: b8 01 10 06 03 74 b4 01 10 07 03 74 b0 01 10 08 03 74 d8 01 00 00 00 00 00 00 00 00 00 00 00 00 00 51 52 55 89 e5 0f 34 cd 80 <5d> 5a 59 c3 90 90 90 90 8d b4 26 00 00 00 00 8d b4 26 00 00 00 00
> > RSP: 002b:00000000f7f1c590 EFLAGS: 00000282 ORIG_RAX: 0000000000000004
> > RAX: ffffffffffffffda RBX: 00000000000000c8 RCX: 0000000020000040
> > RDX: 0000000000000083 RSI: 00000000f734e000 RDI: 0000000000000000
> > RBP: 0000000000000000 R08: 0000000000000000 R09: 0000000000000000
> > R10: 0000000000000000 R11: 0000000000000296 R12: 0000000000000000
> > R13: 0000000000000000 R14: 0000000000000000 R15: 0000000000000000
> >  </TASK>
> > Modules linked in:
> > 
> > Link: https://lore.kernel.org/netdev/CANaxB-yCk8hhP68L4Q2nFOJht8sqgXGGQO2AftpHs0u1xyGG5A@mail.gmail.com/ [1]
> > Fixes: 850cbaddb52d ("udp: use it's own memory accounting schema")
> 
> Thanks for addressing this issue!
> 
> The patch LGTM. 
> 
> Side note: the blamed commit is almost 7y old and the oops should not
> that hard to reproduce by a real app using UDP-lite, but only syzkaller
> stumbled upon it.
> 
> The above looks like a serious hint UDP-lite is not used by anyone
> anymore ?!? Perhaps we could consider deprecating and dropping it? It
> could simplify the UDP code a bit removing a bunch of conditionals in
> fast-path, and that  nowadays would be possibly more relevant?!?

Yes, that crossed my mind too :)

Maybe we can do like this (or drop it immediately now) and see if someone
complains ?

---8<---
diff --git a/net/ipv4/udplite.c b/net/ipv4/udplite.c
index 56d94d23b9e0..39b82082b68f 100644
--- a/net/ipv4/udplite.c
+++ b/net/ipv4/udplite.c
@@ -22,6 +22,7 @@ static int udplite_sk_init(struct sock *sk)
 {
 	udp_init_sock(sk);
 	udp_sk(sk)->pcflag = UDPLITE_BIT;
+	pr_warn("IPPROTO_UDPLITE will be deprecated at the end of 2024\n");
 	return 0;
 }
 
diff --git a/net/ipv6/udplite.c b/net/ipv6/udplite.c
index 3bab0cc13697..54828f08926f 100644
--- a/net/ipv6/udplite.c
+++ b/net/ipv6/udplite.c
@@ -8,6 +8,9 @@
  *  Changes:
  *  Fixes:
  */
+
+#define pr_fmt(fmt) "UDPLite6: " fmt
+
 #include <linux/export.h>
 #include <linux/proc_fs.h>
 #include "udp_impl.h"
@@ -16,6 +19,7 @@ static int udplitev6_sk_init(struct sock *sk)
 {
 	udpv6_init_sock(sk);
 	udp_sk(sk)->pcflag = UDPLITE_BIT;
+	pr_warn("IPPROTO_UDPLITE will be deprecated at the end of 2024\n");
 	return 0;
 }
 
---8<---

Re: [PATCH v1 net] udplite: Fix NULL pointer dereference in __sk_mem_raise_allocated().

[Florian Westphal]

Kuniyuki Iwashima <kuniyu@amazon.com> wrote:
> From: Paolo Abeni <pabeni@redhat.com>
> Date: Thu, 25 May 2023 10:59:09 +0200
> > On Tue, 2023-05-23 at 09:33 -0700, Kuniyuki Iwashima wrote:
> > > syzbot reported [0] a null-ptr-deref in sk_get_rmem0() while using
> > > IPPROTO_UDPLITE (0x88):
> > > 
> > >   14:25:52 executing program 1:
> > >   r0 = socket$inet6(0xa, 0x80002, 0x88)
> > > 
> > > We had a similar report [1] for probably sk_memory_allocated_add()
> > > in __sk_mem_raise_allocated(), and commit c915fe13cbaa ("udplite: fix
> > > NULL pointer dereference") fixed it by setting .memory_allocated for
> > > udplite_prot and udplitev6_prot.
> > > 
> > > To fix the variant, we need to set either .sysctl_wmem_offset or
> > > .sysctl_rmem.
> > > 
> > > Now UDP and UDPLITE share the same value for .memory_allocated, so we
> > > use the same .sysctl_wmem_offset for UDP and UDPLITE.
> > > 
> > > [0]:
> > > general protection fault, probably for non-canonical address 0xdffffc0000000000: 0000 [#1] PREEMPT SMP KASAN
> > > KASAN: null-ptr-deref in range [0x0000000000000000-0x0000000000000007]
> > > CPU: 0 PID: 6829 Comm: syz-executor.1 Not tainted 6.4.0-rc2-syzkaller #0
> > > Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 04/28/2023
> > > RIP: 0010:sk_get_rmem0 include/net/sock.h:2907 [inline]
> > > RIP: 0010:__sk_mem_raise_allocated+0x806/0x17a0 net/core/sock.c:3006
> > > Code: c1 ea 03 80 3c 02 00 0f 85 23 0f 00 00 48 8b 44 24 08 48 8b 98 38 01 00 00 48 b8 00 00 00 00 00 fc ff df 48 89 da 48 c1 ea 03 <0f> b6 14 02 48 89 d8 83 e0 07 83 c0 03 38 d0 0f 8d 6f 0a 00 00 8b
> > > RSP: 0018:ffffc90005d7f450 EFLAGS: 00010246
> > > RAX: dffffc0000000000 RBX: 0000000000000000 RCX: ffffc90004d92000
> > > RDX: 0000000000000000 RSI: ffffffff88066482 RDI: ffffffff8e2ccbb8
> > > RBP: ffff8880173f7000 R08: 0000000000000005 R09: 0000000000000000
> > > R10: 0000000000000000 R11: 0000000000000000 R12: 0000000000030000
> > > R13: 0000000000000001 R14: 0000000000000340 R15: 0000000000000001
> > > FS:  0000000000000000(0000) GS:ffff8880b9800000(0063) knlGS:00000000f7f1cb40
> > > CS:  0010 DS: 002b ES: 002b CR0: 0000000080050033
> > > CR2: 000000002e82f000 CR3: 0000000034ff0000 CR4: 00000000003506f0
> > > Call Trace:
> > >  <TASK>
> > >  __sk_mem_schedule+0x6c/0xe0 net/core/sock.c:3077
> > >  udp_rmem_schedule net/ipv4/udp.c:1539 [inline]
> > >  __udp_enqueue_schedule_skb+0x776/0xb30 net/ipv4/udp.c:1581
> > >  __udpv6_queue_rcv_skb net/ipv6/udp.c:666 [inline]
> > >  udpv6_queue_rcv_one_skb+0xc39/0x16c0 net/ipv6/udp.c:775
> > >  udpv6_queue_rcv_skb+0x194/0xa10 net/ipv6/udp.c:793
> > >  __udp6_lib_mcast_deliver net/ipv6/udp.c:906 [inline]
> > >  __udp6_lib_rcv+0x1bda/0x2bd0 net/ipv6/udp.c:1013
> > >  ip6_protocol_deliver_rcu+0x2e7/0x1250 net/ipv6/ip6_input.c:437
> > >  ip6_input_finish+0x150/0x2f0 net/ipv6/ip6_input.c:482
> > >  NF_HOOK include/linux/netfilter.h:303 [inline]
> > >  NF_HOOK include/linux/netfilter.h:297 [inline]
> > >  ip6_input+0xa0/0xd0 net/ipv6/ip6_input.c:491
> > >  ip6_mc_input+0x40b/0xf50 net/ipv6/ip6_input.c:585
> > >  dst_input include/net/dst.h:468 [inline]
> > >  ip6_rcv_finish net/ipv6/ip6_input.c:79 [inline]
> > >  NF_HOOK include/linux/netfilter.h:303 [inline]
> > >  NF_HOOK include/linux/netfilter.h:297 [inline]
> > >  ipv6_rcv+0x250/0x380 net/ipv6/ip6_input.c:309
> > >  __netif_receive_skb_one_core+0x114/0x180 net/core/dev.c:5491
> > >  __netif_receive_skb+0x1f/0x1c0 net/core/dev.c:5605
> > >  netif_receive_skb_internal net/core/dev.c:5691 [inline]
> > >  netif_receive_skb+0x133/0x7a0 net/core/dev.c:5750
> > >  tun_rx_batched+0x4b3/0x7a0 drivers/net/tun.c:1553
> > >  tun_get_user+0x2452/0x39c0 drivers/net/tun.c:1989
> > >  tun_chr_write_iter+0xdf/0x200 drivers/net/tun.c:2035
> > >  call_write_iter include/linux/fs.h:1868 [inline]
> > >  new_sync_write fs/read_write.c:491 [inline]
> > >  vfs_write+0x945/0xd50 fs/read_write.c:584
> > >  ksys_write+0x12b/0x250 fs/read_write.c:637
> > >  do_syscall_32_irqs_on arch/x86/entry/common.c:112 [inline]
> > >  __do_fast_syscall_32+0x65/0xf0 arch/x86/entry/common.c:178
> > >  do_fast_syscall_32+0x33/0x70 arch/x86/entry/common.c:203
> > >  entry_SYSENTER_compat_after_hwframe+0x70/0x82
> > > RIP: 0023:0xf7f21579
> > > Code: b8 01 10 06 03 74 b4 01 10 07 03 74 b0 01 10 08 03 74 d8 01 00 00 00 00 00 00 00 00 00 00 00 00 00 51 52 55 89 e5 0f 34 cd 80 <5d> 5a 59 c3 90 90 90 90 8d b4 26 00 00 00 00 8d b4 26 00 00 00 00
> > > RSP: 002b:00000000f7f1c590 EFLAGS: 00000282 ORIG_RAX: 0000000000000004
> > > RAX: ffffffffffffffda RBX: 00000000000000c8 RCX: 0000000020000040
> > > RDX: 0000000000000083 RSI: 00000000f734e000 RDI: 0000000000000000
> > > RBP: 0000000000000000 R08: 0000000000000000 R09: 0000000000000000
> > > R10: 0000000000000000 R11: 0000000000000296 R12: 0000000000000000
> > > R13: 0000000000000000 R14: 0000000000000000 R15: 0000000000000000
> > >  </TASK>
> > > Modules linked in:
> > > 
> > > Link: https://lore.kernel.org/netdev/CANaxB-yCk8hhP68L4Q2nFOJht8sqgXGGQO2AftpHs0u1xyGG5A@mail.gmail.com/ [1]
> > > Fixes: 850cbaddb52d ("udp: use it's own memory accounting schema")
> > 
> > Thanks for addressing this issue!
> > 
> > The patch LGTM. 
> > 
> > Side note: the blamed commit is almost 7y old and the oops should not
> > that hard to reproduce by a real app using UDP-lite, but only syzkaller
> > stumbled upon it.
> > 
> > The above looks like a serious hint UDP-lite is not used by anyone
> > anymore ?!? Perhaps we could consider deprecating and dropping it? It
> > could simplify the UDP code a bit removing a bunch of conditionals in
> > fast-path, and that  nowadays would be possibly more relevant?!?
> 
> Yes, that crossed my mind too :)
> 
> Maybe we can do like this (or drop it immediately now) and see if someone
> complains ?

I'd remove it in -next.  Same for DCCP.

Re: [PATCH v1 net] udplite: Fix NULL pointer dereference in __sk_mem_raise_allocated().

[Kuniyuki Iwashima]

From: Florian Westphal <fw@strlen.de>
Date: Thu, 25 May 2023 17:18:42 +0200
> Kuniyuki Iwashima <kuniyu@amazon.com> wrote:
> > From: Paolo Abeni <pabeni@redhat.com>
> > Date: Thu, 25 May 2023 10:59:09 +0200
> > > On Tue, 2023-05-23 at 09:33 -0700, Kuniyuki Iwashima wrote:
> > > > syzbot reported [0] a null-ptr-deref in sk_get_rmem0() while using
> > > > IPPROTO_UDPLITE (0x88):
> > > > 
> > > >   14:25:52 executing program 1:
> > > >   r0 = socket$inet6(0xa, 0x80002, 0x88)
> > > > 
> > > > We had a similar report [1] for probably sk_memory_allocated_add()
> > > > in __sk_mem_raise_allocated(), and commit c915fe13cbaa ("udplite: fix
> > > > NULL pointer dereference") fixed it by setting .memory_allocated for
> > > > udplite_prot and udplitev6_prot.
> > > > 
> > > > To fix the variant, we need to set either .sysctl_wmem_offset or
> > > > .sysctl_rmem.
> > > > 
> > > > Now UDP and UDPLITE share the same value for .memory_allocated, so we
> > > > use the same .sysctl_wmem_offset for UDP and UDPLITE.
> > > > 
> > > > [0]:
> > > > general protection fault, probably for non-canonical address 0xdffffc0000000000: 0000 [#1] PREEMPT SMP KASAN
> > > > KASAN: null-ptr-deref in range [0x0000000000000000-0x0000000000000007]
> > > > CPU: 0 PID: 6829 Comm: syz-executor.1 Not tainted 6.4.0-rc2-syzkaller #0
> > > > Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 04/28/2023
> > > > RIP: 0010:sk_get_rmem0 include/net/sock.h:2907 [inline]
> > > > RIP: 0010:__sk_mem_raise_allocated+0x806/0x17a0 net/core/sock.c:3006
> > > > Code: c1 ea 03 80 3c 02 00 0f 85 23 0f 00 00 48 8b 44 24 08 48 8b 98 38 01 00 00 48 b8 00 00 00 00 00 fc ff df 48 89 da 48 c1 ea 03 <0f> b6 14 02 48 89 d8 83 e0 07 83 c0 03 38 d0 0f 8d 6f 0a 00 00 8b
> > > > RSP: 0018:ffffc90005d7f450 EFLAGS: 00010246
> > > > RAX: dffffc0000000000 RBX: 0000000000000000 RCX: ffffc90004d92000
> > > > RDX: 0000000000000000 RSI: ffffffff88066482 RDI: ffffffff8e2ccbb8
> > > > RBP: ffff8880173f7000 R08: 0000000000000005 R09: 0000000000000000
> > > > R10: 0000000000000000 R11: 0000000000000000 R12: 0000000000030000
> > > > R13: 0000000000000001 R14: 0000000000000340 R15: 0000000000000001
> > > > FS:  0000000000000000(0000) GS:ffff8880b9800000(0063) knlGS:00000000f7f1cb40
> > > > CS:  0010 DS: 002b ES: 002b CR0: 0000000080050033
> > > > CR2: 000000002e82f000 CR3: 0000000034ff0000 CR4: 00000000003506f0
> > > > Call Trace:
> > > >  <TASK>
> > > >  __sk_mem_schedule+0x6c/0xe0 net/core/sock.c:3077
> > > >  udp_rmem_schedule net/ipv4/udp.c:1539 [inline]
> > > >  __udp_enqueue_schedule_skb+0x776/0xb30 net/ipv4/udp.c:1581
> > > >  __udpv6_queue_rcv_skb net/ipv6/udp.c:666 [inline]
> > > >  udpv6_queue_rcv_one_skb+0xc39/0x16c0 net/ipv6/udp.c:775
> > > >  udpv6_queue_rcv_skb+0x194/0xa10 net/ipv6/udp.c:793
> > > >  __udp6_lib_mcast_deliver net/ipv6/udp.c:906 [inline]
> > > >  __udp6_lib_rcv+0x1bda/0x2bd0 net/ipv6/udp.c:1013
> > > >  ip6_protocol_deliver_rcu+0x2e7/0x1250 net/ipv6/ip6_input.c:437
> > > >  ip6_input_finish+0x150/0x2f0 net/ipv6/ip6_input.c:482
> > > >  NF_HOOK include/linux/netfilter.h:303 [inline]
> > > >  NF_HOOK include/linux/netfilter.h:297 [inline]
> > > >  ip6_input+0xa0/0xd0 net/ipv6/ip6_input.c:491
> > > >  ip6_mc_input+0x40b/0xf50 net/ipv6/ip6_input.c:585
> > > >  dst_input include/net/dst.h:468 [inline]
> > > >  ip6_rcv_finish net/ipv6/ip6_input.c:79 [inline]
> > > >  NF_HOOK include/linux/netfilter.h:303 [inline]
> > > >  NF_HOOK include/linux/netfilter.h:297 [inline]
> > > >  ipv6_rcv+0x250/0x380 net/ipv6/ip6_input.c:309
> > > >  __netif_receive_skb_one_core+0x114/0x180 net/core/dev.c:5491
> > > >  __netif_receive_skb+0x1f/0x1c0 net/core/dev.c:5605
> > > >  netif_receive_skb_internal net/core/dev.c:5691 [inline]
> > > >  netif_receive_skb+0x133/0x7a0 net/core/dev.c:5750
> > > >  tun_rx_batched+0x4b3/0x7a0 drivers/net/tun.c:1553
> > > >  tun_get_user+0x2452/0x39c0 drivers/net/tun.c:1989
> > > >  tun_chr_write_iter+0xdf/0x200 drivers/net/tun.c:2035
> > > >  call_write_iter include/linux/fs.h:1868 [inline]
> > > >  new_sync_write fs/read_write.c:491 [inline]
> > > >  vfs_write+0x945/0xd50 fs/read_write.c:584
> > > >  ksys_write+0x12b/0x250 fs/read_write.c:637
> > > >  do_syscall_32_irqs_on arch/x86/entry/common.c:112 [inline]
> > > >  __do_fast_syscall_32+0x65/0xf0 arch/x86/entry/common.c:178
> > > >  do_fast_syscall_32+0x33/0x70 arch/x86/entry/common.c:203
> > > >  entry_SYSENTER_compat_after_hwframe+0x70/0x82
> > > > RIP: 0023:0xf7f21579
> > > > Code: b8 01 10 06 03 74 b4 01 10 07 03 74 b0 01 10 08 03 74 d8 01 00 00 00 00 00 00 00 00 00 00 00 00 00 51 52 55 89 e5 0f 34 cd 80 <5d> 5a 59 c3 90 90 90 90 8d b4 26 00 00 00 00 8d b4 26 00 00 00 00
> > > > RSP: 002b:00000000f7f1c590 EFLAGS: 00000282 ORIG_RAX: 0000000000000004
> > > > RAX: ffffffffffffffda RBX: 00000000000000c8 RCX: 0000000020000040
> > > > RDX: 0000000000000083 RSI: 00000000f734e000 RDI: 0000000000000000
> > > > RBP: 0000000000000000 R08: 0000000000000000 R09: 0000000000000000
> > > > R10: 0000000000000000 R11: 0000000000000296 R12: 0000000000000000
> > > > R13: 0000000000000000 R14: 0000000000000000 R15: 0000000000000000
> > > >  </TASK>
> > > > Modules linked in:
> > > > 
> > > > Link: https://lore.kernel.org/netdev/CANaxB-yCk8hhP68L4Q2nFOJht8sqgXGGQO2AftpHs0u1xyGG5A@mail.gmail.com/ [1]
> > > > Fixes: 850cbaddb52d ("udp: use it's own memory accounting schema")
> > > 
> > > Thanks for addressing this issue!
> > > 
> > > The patch LGTM. 
> > > 
> > > Side note: the blamed commit is almost 7y old and the oops should not
> > > that hard to reproduce by a real app using UDP-lite, but only syzkaller
> > > stumbled upon it.
> > > 
> > > The above looks like a serious hint UDP-lite is not used by anyone
> > > anymore ?!? Perhaps we could consider deprecating and dropping it? It
> > > could simplify the UDP code a bit removing a bunch of conditionals in
> > > fast-path, and that  nowadays would be possibly more relevant?!?
> > 
> > Yes, that crossed my mind too :)
> > 
> > Maybe we can do like this (or drop it immediately now) and see if someone
> > complains ?
> 
> I'd remove it in -next.  Same for DCCP.

Ok, I'll do for UDP Lite.  +1 for DCCP, but we know there are real?
still experimenting? users ... ?

https://lore.kernel.org/netdev/20230519082143.3d20db49@kernel.org/

Re: [PATCH v1 net] udplite: Fix NULL pointer dereference in __sk_mem_raise_allocated().

[Florian Westphal]

Kuniyuki Iwashima <kuniyu@amazon.com> wrote:
> > I'd remove it in -next.  Same for DCCP.
> 
> Ok, I'll do for UDP Lite.

Thanks.

> +1 for DCCP, but we know there are real?
> still experimenting? users ... ?

Yes, and they can continue to work on their out of tree fork
and research projects, no problem.

I'd say next time some net/core change needs dccp changes,
remove dccp first (or mark it as CONFIG_BROKEN) so it doesn't
cause extra work.

DCCP can be brought back when someone has interest to maintain it.

Looking at DCCP patches its either:
1. odd syzbot fixes
2. api changes in net that need folloup changes in dccp
3. automated transformations

There is no sign that anyone is maintaining this (or running it
in a production environment...).

Re: [PATCH v1 net] udplite: Fix NULL pointer dereference in __sk_mem_raise_allocated().

[Kuniyuki Iwashima]

From: Florian Westphal <fw@strlen.de>
Date: Thu, 25 May 2023 18:33:42 +0200
> Kuniyuki Iwashima <kuniyu@amazon.com> wrote:
> > > I'd remove it in -next.  Same for DCCP.
> > 
> > Ok, I'll do for UDP Lite.
> 
> Thanks.
> 
> > +1 for DCCP, but we know there are real?
> > still experimenting? users ... ?
> 
> Yes, and they can continue to work on their out of tree fork
> and research projects, no problem.
> 
> I'd say next time some net/core change needs dccp changes,
> remove dccp first (or mark it as CONFIG_BROKEN) so it doesn't
> cause extra work.

FWIW, I was going to post such a patch that removes .twsk_unique
and .twsk_destructor handler in timewait_sock_ops, which is only
used by TCP but exists just because DCCP shares the struct.


> DCCP can be brought back when someone has interest to maintain it.
> 
> Looking at DCCP patches its either:
> 1. odd syzbot fixes
> 2. api changes in net that need folloup changes in dccp
> 3. automated transformations
> 
> There is no sign that anyone is maintaining this (or running it
> in a production environment...).

Exactly.  It's now kind of bleeding ground of CVE.

Actualy, we disable CONFIG_IP_DCCP for our latest distribution (AL2023)
for the reason, and RHEL 7.8+ also prevents the module from being loaded
by default.

If there's no objection, I can remove it after UDP Lite.

https://access.redhat.com/documentation/en-us/red_hat_enterprise_linux/7/html/7.8_release_notes/deprecated_functionality#automatic_loading_of_dccp_modules_through_socket_layer_is_now_disabled_by_default