* KMSAN: kernel-infoleak in sctp_getsockopt
@ 2018-12-05 19:31 syzbot
2018-12-06 10:36 ` Alexander Potapenko
0 siblings, 1 reply; 9+ messages in thread
From: syzbot @ 2018-12-05 19:31 UTC (permalink / raw)
To: davem, linux-kernel, linux-sctp, marcelo.leitner, netdev,
nhorman, syzkaller-bugs, vyasevich
Hello,
syzbot found the following crash on:
HEAD commit: fffec98ae2a6 net: proper support for CONFIG_GENERIC_CSUM o..
git tree: https://github.com/google/kmsan.git/master
console output: https://syzkaller.appspot.com/x/log.txt?x=12e84a47400000
kernel config: https://syzkaller.appspot.com/x/.config?x=56b48b46dafe4516
dashboard link: https://syzkaller.appspot.com/bug?extid=ad5d327e6936a2e284be
compiler: clang version 8.0.0 (trunk 343298)
syz repro: https://syzkaller.appspot.com/x/repro.syz?x=103cd225400000
IMPORTANT: if you fix the bug, please add the following tag to the commit:
Reported-by: syzbot+ad5d327e6936a2e284be@syzkaller.appspotmail.com
8021q: adding VLAN 0 to HW filter on device team0
8021q: adding VLAN 0 to HW filter on device team0
8021q: adding VLAN 0 to HW filter on device team0
8021q: adding VLAN 0 to HW filter on device team0
==================================================================
BUG: KMSAN: kernel-infoleak in _copy_to_user+0x19a/0x230 lib/usercopy.c:33
CPU: 1 PID: 8164 Comm: syz-executor2 Not tainted 4.20.0-rc3+ #95
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS
Google 01/01/2011
Call Trace:
__dump_stack lib/dump_stack.c:77 [inline]
dump_stack+0x32d/0x480 lib/dump_stack.c:113
kmsan_report+0x12c/0x290 mm/kmsan/kmsan.c:683
kmsan_internal_check_memory+0x32a/0xa50 mm/kmsan/kmsan.c:743
kmsan_copy_to_user+0x78/0xd0 mm/kmsan/kmsan_hooks.c:634
_copy_to_user+0x19a/0x230 lib/usercopy.c:33
copy_to_user include/linux/uaccess.h:183 [inline]
sctp_getsockopt_local_addrs net/sctp/socket.c:5998 [inline]
sctp_getsockopt+0x15248/0x186f0 net/sctp/socket.c:7477
sock_common_getsockopt+0x13f/0x180 net/core/sock.c:2937
__sys_getsockopt+0x489/0x550 net/socket.c:1939
__do_sys_getsockopt net/socket.c:1950 [inline]
__se_sys_getsockopt+0xe1/0x100 net/socket.c:1947
__x64_sys_getsockopt+0x62/0x80 net/socket.c:1947
do_syscall_64+0xcf/0x110 arch/x86/entry/common.c:291
entry_SYSCALL_64_after_hwframe+0x63/0xe7
RIP: 0033:0x457569
Code: fd b3 fb ff c3 66 2e 0f 1f 84 00 00 00 00 00 66 90 48 89 f8 48 89 f7
48 89 d6 48 89 ca 4d 89 c2 4d 89 c8 4c 8b 4c 24 08 0f 05 <48> 3d 01 f0 ff
ff 0f 83 cb b3 fb ff c3 66 2e 0f 1f 84 00 00 00 00
RSP: 002b:00007f4991886c78 EFLAGS: 00000246 ORIG_RAX: 0000000000000037
RAX: ffffffffffffffda RBX: 0000000000000005 RCX: 0000000000457569
RDX: 000000000000006d RSI: 0000000000000084 RDI: 0000000000000003
RBP: 000000000072bf00 R08: 0000000020000140 R09: 0000000000000000
R10: 0000000020001100 R11: 0000000000000246 R12: 00007f49918876d4
R13: 00000000004c7d88 R14: 00000000004ce348 R15: 00000000ffffffff
Uninit was stored to memory at:
kmsan_save_stack_with_flags mm/kmsan/kmsan.c:246 [inline]
kmsan_save_stack mm/kmsan/kmsan.c:261 [inline]
kmsan_internal_chain_origin+0x13d/0x240 mm/kmsan/kmsan.c:469
kmsan_memcpy_memmove_metadata+0x1a9/0xf70 mm/kmsan/kmsan.c:344
kmsan_memcpy_metadata+0xb/0x10 mm/kmsan/kmsan.c:362
__msan_memcpy+0x61/0x70 mm/kmsan/kmsan_instr.c:162
sctp_copy_laddrs net/sctp/socket.c:5901 [inline]
sctp_getsockopt_local_addrs net/sctp/socket.c:5967 [inline]
sctp_getsockopt+0x14f41/0x186f0 net/sctp/socket.c:7477
sock_common_getsockopt+0x13f/0x180 net/core/sock.c:2937
__sys_getsockopt+0x489/0x550 net/socket.c:1939
__do_sys_getsockopt net/socket.c:1950 [inline]
__se_sys_getsockopt+0xe1/0x100 net/socket.c:1947
__x64_sys_getsockopt+0x62/0x80 net/socket.c:1947
do_syscall_64+0xcf/0x110 arch/x86/entry/common.c:291
entry_SYSCALL_64_after_hwframe+0x63/0xe7
Uninit was stored to memory at:
kmsan_save_stack_with_flags mm/kmsan/kmsan.c:246 [inline]
kmsan_save_stack mm/kmsan/kmsan.c:261 [inline]
kmsan_internal_chain_origin+0x13d/0x240 mm/kmsan/kmsan.c:469
kmsan_memcpy_memmove_metadata+0x1a9/0xf70 mm/kmsan/kmsan.c:344
kmsan_memcpy_metadata+0xb/0x10 mm/kmsan/kmsan.c:362
__msan_memcpy+0x61/0x70 mm/kmsan/kmsan_instr.c:162
sctp_copy_laddrs net/sctp/socket.c:5890 [inline]
sctp_getsockopt_local_addrs net/sctp/socket.c:5967 [inline]
sctp_getsockopt+0x14de8/0x186f0 net/sctp/socket.c:7477
sock_common_getsockopt+0x13f/0x180 net/core/sock.c:2937
__sys_getsockopt+0x489/0x550 net/socket.c:1939
__do_sys_getsockopt net/socket.c:1950 [inline]
__se_sys_getsockopt+0xe1/0x100 net/socket.c:1947
__x64_sys_getsockopt+0x62/0x80 net/socket.c:1947
do_syscall_64+0xcf/0x110 arch/x86/entry/common.c:291
entry_SYSCALL_64_after_hwframe+0x63/0xe7
Uninit was created at:
kmsan_save_stack_with_flags mm/kmsan/kmsan.c:246 [inline]
kmsan_internal_poison_shadow+0x6d/0x130 mm/kmsan/kmsan.c:170
kmsan_kmalloc+0xa1/0x100 mm/kmsan/kmsan_hooks.c:186
__kmalloc+0x14c/0x4d0 mm/slub.c:3825
kmalloc include/linux/slab.h:551 [inline]
sctp_inet6addr_event+0x60e/0xbd0 net/sctp/ipv6.c:100
notifier_call_chain kernel/notifier.c:93 [inline]
__atomic_notifier_call_chain kernel/notifier.c:183 [inline]
atomic_notifier_call_chain+0x13d/0x240 kernel/notifier.c:193
inet6addr_notifier_call_chain+0x76/0x90 net/ipv6/addrconf_core.c:107
ipv6_add_addr+0x2597/0x2890 net/ipv6/addrconf.c:1115
inet6_addr_add+0xc86/0x1c10 net/ipv6/addrconf.c:2912
inet6_rtm_newaddr+0x167e/0x3d20 net/ipv6/addrconf.c:4750
rtnetlink_rcv_msg+0x1148/0x1540 net/core/rtnetlink.c:4947
netlink_rcv_skb+0x394/0x640 net/netlink/af_netlink.c:2477
rtnetlink_rcv+0x50/0x60 net/core/rtnetlink.c:4965
netlink_unicast_kernel net/netlink/af_netlink.c:1310 [inline]
netlink_unicast+0x1699/0x1740 net/netlink/af_netlink.c:1336
netlink_sendmsg+0x13c7/0x1440 net/netlink/af_netlink.c:1917
sock_sendmsg_nosec net/socket.c:621 [inline]
sock_sendmsg net/socket.c:631 [inline]
___sys_sendmsg+0xe3b/0x1240 net/socket.c:2116
__sys_sendmsg net/socket.c:2154 [inline]
__do_sys_sendmsg net/socket.c:2163 [inline]
__se_sys_sendmsg+0x305/0x460 net/socket.c:2161
__x64_sys_sendmsg+0x4a/0x70 net/socket.c:2161
do_syscall_64+0xcf/0x110 arch/x86/entry/common.c:291
entry_SYSCALL_64_after_hwframe+0x63/0xe7
Bytes 32-35 of 2100 are uninitialized
Memory access of size 2100 starts at ffff888185d8b000
Data copied to user address 0000000020001108
==================================================================
---
This bug is generated by a bot. It may contain errors.
See https://goo.gl/tpsmEJ for more information about syzbot.
syzbot engineers can be reached at syzkaller@googlegroups.com.
syzbot will keep track of this bug report. See:
https://goo.gl/tpsmEJ#bug-status-tracking for how to communicate with
syzbot.
syzbot can test patches for this bug, for details see:
https://goo.gl/tpsmEJ#testing-patches
^ permalink raw reply [flat|nested] 9+ messages in thread
* Re: KMSAN: kernel-infoleak in sctp_getsockopt
2018-12-05 19:31 KMSAN: kernel-infoleak in sctp_getsockopt syzbot
@ 2018-12-06 10:36 ` Alexander Potapenko
2018-12-06 11:06 ` Marcelo Ricardo Leitner
0 siblings, 1 reply; 9+ messages in thread
From: Alexander Potapenko @ 2018-12-06 10:36 UTC (permalink / raw)
To: syzbot+ad5d327e6936a2e284be
Cc: David Miller, LKML, linux-sctp, Marcelo Ricardo Leitner,
Networking, nhorman, syzkaller-bugs, Vladislav Yasevich
[-- Attachment #1: Type: text/plain, Size: 8207 bytes --]
On Wed, Dec 5, 2018 at 8:31 PM syzbot
<syzbot+ad5d327e6936a2e284be@syzkaller.appspotmail.com> wrote:
>
> Hello,
>
> syzbot found the following crash on:
>
> HEAD commit: fffec98ae2a6 net: proper support for CONFIG_GENERIC_CSUM o..
> git tree: https://github.com/google/kmsan.git/master
> console output: https://syzkaller.appspot.com/x/log.txt?x=12e84a47400000
> kernel config: https://syzkaller.appspot.com/x/.config?x=56b48b46dafe4516
> dashboard link: https://syzkaller.appspot.com/bug?extid=ad5d327e6936a2e284be
> compiler: clang version 8.0.0 (trunk 343298)
> syz repro: https://syzkaller.appspot.com/x/repro.syz?x=103cd225400000
>
> IMPORTANT: if you fix the bug, please add the following tag to the commit:
> Reported-by: syzbot+ad5d327e6936a2e284be@syzkaller.appspotmail.com
>
> 8021q: adding VLAN 0 to HW filter on device team0
> 8021q: adding VLAN 0 to HW filter on device team0
> 8021q: adding VLAN 0 to HW filter on device team0
> 8021q: adding VLAN 0 to HW filter on device team0
> ==================================================================
> BUG: KMSAN: kernel-infoleak in _copy_to_user+0x19a/0x230 lib/usercopy.c:33
> CPU: 1 PID: 8164 Comm: syz-executor2 Not tainted 4.20.0-rc3+ #95
> Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS
> Google 01/01/2011
> Call Trace:
> __dump_stack lib/dump_stack.c:77 [inline]
> dump_stack+0x32d/0x480 lib/dump_stack.c:113
> kmsan_report+0x12c/0x290 mm/kmsan/kmsan.c:683
> kmsan_internal_check_memory+0x32a/0xa50 mm/kmsan/kmsan.c:743
> kmsan_copy_to_user+0x78/0xd0 mm/kmsan/kmsan_hooks.c:634
> _copy_to_user+0x19a/0x230 lib/usercopy.c:33
> copy_to_user include/linux/uaccess.h:183 [inline]
> sctp_getsockopt_local_addrs net/sctp/socket.c:5998 [inline]
> sctp_getsockopt+0x15248/0x186f0 net/sctp/socket.c:7477
> sock_common_getsockopt+0x13f/0x180 net/core/sock.c:2937
> __sys_getsockopt+0x489/0x550 net/socket.c:1939
> __do_sys_getsockopt net/socket.c:1950 [inline]
> __se_sys_getsockopt+0xe1/0x100 net/socket.c:1947
> __x64_sys_getsockopt+0x62/0x80 net/socket.c:1947
> do_syscall_64+0xcf/0x110 arch/x86/entry/common.c:291
> entry_SYSCALL_64_after_hwframe+0x63/0xe7
> RIP: 0033:0x457569
> Code: fd b3 fb ff c3 66 2e 0f 1f 84 00 00 00 00 00 66 90 48 89 f8 48 89 f7
> 48 89 d6 48 89 ca 4d 89 c2 4d 89 c8 4c 8b 4c 24 08 0f 05 <48> 3d 01 f0 ff
> ff 0f 83 cb b3 fb ff c3 66 2e 0f 1f 84 00 00 00 00
> RSP: 002b:00007f4991886c78 EFLAGS: 00000246 ORIG_RAX: 0000000000000037
> RAX: ffffffffffffffda RBX: 0000000000000005 RCX: 0000000000457569
> RDX: 000000000000006d RSI: 0000000000000084 RDI: 0000000000000003
> RBP: 000000000072bf00 R08: 0000000020000140 R09: 0000000000000000
> R10: 0000000020001100 R11: 0000000000000246 R12: 00007f49918876d4
> R13: 00000000004c7d88 R14: 00000000004ce348 R15: 00000000ffffffff
>
> Uninit was stored to memory at:
> kmsan_save_stack_with_flags mm/kmsan/kmsan.c:246 [inline]
> kmsan_save_stack mm/kmsan/kmsan.c:261 [inline]
> kmsan_internal_chain_origin+0x13d/0x240 mm/kmsan/kmsan.c:469
> kmsan_memcpy_memmove_metadata+0x1a9/0xf70 mm/kmsan/kmsan.c:344
> kmsan_memcpy_metadata+0xb/0x10 mm/kmsan/kmsan.c:362
> __msan_memcpy+0x61/0x70 mm/kmsan/kmsan_instr.c:162
> sctp_copy_laddrs net/sctp/socket.c:5901 [inline]
> sctp_getsockopt_local_addrs net/sctp/socket.c:5967 [inline]
> sctp_getsockopt+0x14f41/0x186f0 net/sctp/socket.c:7477
> sock_common_getsockopt+0x13f/0x180 net/core/sock.c:2937
> __sys_getsockopt+0x489/0x550 net/socket.c:1939
> __do_sys_getsockopt net/socket.c:1950 [inline]
> __se_sys_getsockopt+0xe1/0x100 net/socket.c:1947
> __x64_sys_getsockopt+0x62/0x80 net/socket.c:1947
> do_syscall_64+0xcf/0x110 arch/x86/entry/common.c:291
> entry_SYSCALL_64_after_hwframe+0x63/0xe7
>
> Uninit was stored to memory at:
> kmsan_save_stack_with_flags mm/kmsan/kmsan.c:246 [inline]
> kmsan_save_stack mm/kmsan/kmsan.c:261 [inline]
> kmsan_internal_chain_origin+0x13d/0x240 mm/kmsan/kmsan.c:469
> kmsan_memcpy_memmove_metadata+0x1a9/0xf70 mm/kmsan/kmsan.c:344
> kmsan_memcpy_metadata+0xb/0x10 mm/kmsan/kmsan.c:362
> __msan_memcpy+0x61/0x70 mm/kmsan/kmsan_instr.c:162
> sctp_copy_laddrs net/sctp/socket.c:5890 [inline]
> sctp_getsockopt_local_addrs net/sctp/socket.c:5967 [inline]
> sctp_getsockopt+0x14de8/0x186f0 net/sctp/socket.c:7477
> sock_common_getsockopt+0x13f/0x180 net/core/sock.c:2937
> __sys_getsockopt+0x489/0x550 net/socket.c:1939
> __do_sys_getsockopt net/socket.c:1950 [inline]
> __se_sys_getsockopt+0xe1/0x100 net/socket.c:1947
> __x64_sys_getsockopt+0x62/0x80 net/socket.c:1947
> do_syscall_64+0xcf/0x110 arch/x86/entry/common.c:291
> entry_SYSCALL_64_after_hwframe+0x63/0xe7
>
> Uninit was created at:
> kmsan_save_stack_with_flags mm/kmsan/kmsan.c:246 [inline]
> kmsan_internal_poison_shadow+0x6d/0x130 mm/kmsan/kmsan.c:170
> kmsan_kmalloc+0xa1/0x100 mm/kmsan/kmsan_hooks.c:186
> __kmalloc+0x14c/0x4d0 mm/slub.c:3825
> kmalloc include/linux/slab.h:551 [inline]
> sctp_inet6addr_event+0x60e/0xbd0 net/sctp/ipv6.c:100
> notifier_call_chain kernel/notifier.c:93 [inline]
> __atomic_notifier_call_chain kernel/notifier.c:183 [inline]
> atomic_notifier_call_chain+0x13d/0x240 kernel/notifier.c:193
> inet6addr_notifier_call_chain+0x76/0x90 net/ipv6/addrconf_core.c:107
> ipv6_add_addr+0x2597/0x2890 net/ipv6/addrconf.c:1115
> inet6_addr_add+0xc86/0x1c10 net/ipv6/addrconf.c:2912
> inet6_rtm_newaddr+0x167e/0x3d20 net/ipv6/addrconf.c:4750
> rtnetlink_rcv_msg+0x1148/0x1540 net/core/rtnetlink.c:4947
> netlink_rcv_skb+0x394/0x640 net/netlink/af_netlink.c:2477
> rtnetlink_rcv+0x50/0x60 net/core/rtnetlink.c:4965
> netlink_unicast_kernel net/netlink/af_netlink.c:1310 [inline]
> netlink_unicast+0x1699/0x1740 net/netlink/af_netlink.c:1336
> netlink_sendmsg+0x13c7/0x1440 net/netlink/af_netlink.c:1917
> sock_sendmsg_nosec net/socket.c:621 [inline]
> sock_sendmsg net/socket.c:631 [inline]
> ___sys_sendmsg+0xe3b/0x1240 net/socket.c:2116
> __sys_sendmsg net/socket.c:2154 [inline]
> __do_sys_sendmsg net/socket.c:2163 [inline]
> __se_sys_sendmsg+0x305/0x460 net/socket.c:2161
> __x64_sys_sendmsg+0x4a/0x70 net/socket.c:2161
> do_syscall_64+0xcf/0x110 arch/x86/entry/common.c:291
> entry_SYSCALL_64_after_hwframe+0x63/0xe7
>
> Bytes 32-35 of 2100 are uninitialized
> Memory access of size 2100 starts at ffff888185d8b000
> Data copied to user address 0000000020001108
> ==================================================================
When a network device goes up and sctp_inetaddr_event() is called, it
allocates a partially initialized struct sctp_sockaddr_entry to hold
the newly created address.
The attached reproducer can be then used to read up to 8 uninit bytes
for each of the local addresses.
I guess the devices aren't created so often that this can pose any
security risk, but we probably still need to allocate this structure
with __GFP_ZERO.
>
> ---
> This bug is generated by a bot. It may contain errors.
> See https://goo.gl/tpsmEJ for more information about syzbot.
> syzbot engineers can be reached at syzkaller@googlegroups.com.
>
> syzbot will keep track of this bug report. See:
> https://goo.gl/tpsmEJ#bug-status-tracking for how to communicate with
> syzbot.
> syzbot can test patches for this bug, for details see:
> https://goo.gl/tpsmEJ#testing-patches
>
> --
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--
Alexander Potapenko
Software Engineer
Google Germany GmbH
Erika-Mann-Straße, 33
80636 München
Geschäftsführer: Paul Manicle, Halimah DeLaine Prado
Registergericht und -nummer: Hamburg, HRB 86891
Sitz der Gesellschaft: Hamburg
[-- Attachment #2: dump_buf.h --]
[-- Type: text/x-chdr, Size: 1701 bytes --]
#ifndef DUMP_BUF_H
#define DUMP_BUF_H
#ifndef DUMP_MIN_STRLEN
#define DUMP_MIN_STRLEN 1
#endif
#ifndef DUMP_PARALLEL
#define DUMP_PARALLEL 0
#endif
#ifndef DUMP_PRINT_BUF_ADDR
#define DUMP_PRINT_BUF_ADDR 0
#endif
#ifndef DUMP_PRINT_HEX
#define DUMP_PRINT_HEX 0
#endif
#ifndef DUMP_PRINT_STRING
#define DUMP_PRINT_STRING 0
#endif
#if DUMP_PARALLEL
pthread_mutex_t out_mutex = PTHREAD_MUTEX_INITIALIZER;
#endif
void dump_buf(unsigned char *buf, int len) {
int i, nz = 0;
for (i = 0; i < len; i++) {
if (buf[i]) {
nz = 1;
break;
}
}
if (!nz) {
// The buffer is empty.
return;
} else {
#if DUMP_PARALLEL
pthread_mutex_lock(&out_mutex);
#endif
#if DUMP_PRINT_BUF_ADDR
fprintf(stderr, "nonempty buffer at %p\n", buf);
#endif
#if DUMP_PRINT_HEX
for (i=0; i < len; i++) {
if (buf[i]) {
fprintf(stderr, "buf[%d]: %x (%p)\n", i, buf[i], *(void**)&buf[i]);
}
}
#endif // DUMP_PRINT_HEX
#if DUMP_PARALLEL
pthread_mutex_unlock(&out_mutex);
#endif
}
#if DUMP_PARALLEL
pthread_mutex_lock(&out_mutex);
#endif
#if DUMP_PRINT_STRING
for (i = 0; i < len; i++) {
if (buf[i]) {
int str_len = strlen(&buf[i]);
// Short string pieces are too boring.
if (str_len >= DUMP_MIN_STRLEN) {
unsigned char *c;
for (c = &buf[i]; c < &buf[i + str_len]; c++) {
if ((*c > 127) || ((*c < 32) && (*c != 10) && (*c != 13))) {
*c = ' ';
continue;
}
}
// Dump the buffer.
fprintf(stderr, "%s\n", &buf[i]);
}
i += str_len;
}
}
#endif // DUMP_PRINT_STRING
#if DUMP_PARALLEL
pthread_mutex_unlock(&out_mutex);
#endif
}
#endif
[-- Attachment #3: getsockopt.c --]
[-- Type: text/x-csrc, Size: 1168 bytes --]
#include <stdio.h>
#include <pthread.h>
#include <sys/types.h> /* See NOTES */
#include <sys/socket.h>
#include <unistd.h>
#define DUMP_PARALLEL 1
#define DUMP_PRINT_BUF_ADDR 1
#define DUMP_PRINT_STRING 1
#define DUMP_PRINT_HEX 1
#include "dump_buf.h"
void *setsockopt_fn(void *arg) {
int sock = (int)arg;
struct sockaddr addr;
memset(&addr, 0, sizeof(addr));
addr.sa_family = 2;
addr.sa_data[2] = 0xac;
addr.sa_data[3] = 0x14;
addr.sa_data[4] = 0x14;
setsockopt(sock, 0x84, 0x6e, &addr, 0x10);
}
#define BUFLEN (0x2c2)
void *getsockopt_fn(void *arg) {
int sock = (int)arg;
char buf[BUFLEN];
memset(buf, 0, BUFLEN);
int socklen = BUFLEN;
getsockopt(sock, 0x84, /*SCTP_GET_LOCAL_ADDRS*/0x6d, buf, &socklen);
dump_buf(&(buf[8]), 32);
}
void do_work(int sock) {
pthread_t t1, t2;
for (int i = 0; i < 10; i++) {
pthread_create(&t1, NULL, getsockopt_fn, (void*)sock);
pthread_create(&t2, NULL, setsockopt_fn, (void*)sock);
usleep(100);
}
}
int main(int argc, char *argv[]) {
int res;
int pid = fork();
if (pid == 0) {
int sock = socket(0x2, 0x1, 0x84);
do_work(sock);
}
sleep(10);
return 0;
}
^ permalink raw reply [flat|nested] 9+ messages in thread
* Re: KMSAN: kernel-infoleak in sctp_getsockopt
2018-12-06 10:36 ` Alexander Potapenko
@ 2018-12-06 11:06 ` Marcelo Ricardo Leitner
2018-12-06 11:35 ` Alexander Potapenko
2018-12-10 8:56 ` Xin Long
0 siblings, 2 replies; 9+ messages in thread
From: Marcelo Ricardo Leitner @ 2018-12-06 11:06 UTC (permalink / raw)
To: Alexander Potapenko
Cc: syzbot+ad5d327e6936a2e284be, David Miller, LKML, linux-sctp,
Networking, nhorman, syzkaller-bugs, Vladislav Yasevich
On Thu, Dec 06, 2018 at 11:36:08AM +0100, Alexander Potapenko wrote:
> On Wed, Dec 5, 2018 at 8:31 PM syzbot
> <syzbot+ad5d327e6936a2e284be@syzkaller.appspotmail.com> wrote:
> >
> > Hello,
> >
> > syzbot found the following crash on:
> >
> > HEAD commit: fffec98ae2a6 net: proper support for CONFIG_GENERIC_CSUM o..
> > git tree: https://github.com/google/kmsan.git/master
> > console output: https://syzkaller.appspot.com/x/log.txt?x=12e84a47400000
> > kernel config: https://syzkaller.appspot.com/x/.config?x=56b48b46dafe4516
> > dashboard link: https://syzkaller.appspot.com/bug?extid=ad5d327e6936a2e284be
> > compiler: clang version 8.0.0 (trunk 343298)
> > syz repro: https://syzkaller.appspot.com/x/repro.syz?x=103cd225400000
> >
> > IMPORTANT: if you fix the bug, please add the following tag to the commit:
> > Reported-by: syzbot+ad5d327e6936a2e284be@syzkaller.appspotmail.com
> >
> > 8021q: adding VLAN 0 to HW filter on device team0
> > 8021q: adding VLAN 0 to HW filter on device team0
> > 8021q: adding VLAN 0 to HW filter on device team0
> > 8021q: adding VLAN 0 to HW filter on device team0
> > ==================================================================
> > BUG: KMSAN: kernel-infoleak in _copy_to_user+0x19a/0x230 lib/usercopy.c:33
> > CPU: 1 PID: 8164 Comm: syz-executor2 Not tainted 4.20.0-rc3+ #95
> > Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS
> > Google 01/01/2011
> > Call Trace:
> > __dump_stack lib/dump_stack.c:77 [inline]
> > dump_stack+0x32d/0x480 lib/dump_stack.c:113
> > kmsan_report+0x12c/0x290 mm/kmsan/kmsan.c:683
> > kmsan_internal_check_memory+0x32a/0xa50 mm/kmsan/kmsan.c:743
> > kmsan_copy_to_user+0x78/0xd0 mm/kmsan/kmsan_hooks.c:634
> > _copy_to_user+0x19a/0x230 lib/usercopy.c:33
> > copy_to_user include/linux/uaccess.h:183 [inline]
> > sctp_getsockopt_local_addrs net/sctp/socket.c:5998 [inline]
> > sctp_getsockopt+0x15248/0x186f0 net/sctp/socket.c:7477
> > sock_common_getsockopt+0x13f/0x180 net/core/sock.c:2937
> > __sys_getsockopt+0x489/0x550 net/socket.c:1939
> > __do_sys_getsockopt net/socket.c:1950 [inline]
> > __se_sys_getsockopt+0xe1/0x100 net/socket.c:1947
> > __x64_sys_getsockopt+0x62/0x80 net/socket.c:1947
> > do_syscall_64+0xcf/0x110 arch/x86/entry/common.c:291
> > entry_SYSCALL_64_after_hwframe+0x63/0xe7
> > RIP: 0033:0x457569
> > Code: fd b3 fb ff c3 66 2e 0f 1f 84 00 00 00 00 00 66 90 48 89 f8 48 89 f7
> > 48 89 d6 48 89 ca 4d 89 c2 4d 89 c8 4c 8b 4c 24 08 0f 05 <48> 3d 01 f0 ff
> > ff 0f 83 cb b3 fb ff c3 66 2e 0f 1f 84 00 00 00 00
> > RSP: 002b:00007f4991886c78 EFLAGS: 00000246 ORIG_RAX: 0000000000000037
> > RAX: ffffffffffffffda RBX: 0000000000000005 RCX: 0000000000457569
> > RDX: 000000000000006d RSI: 0000000000000084 RDI: 0000000000000003
> > RBP: 000000000072bf00 R08: 0000000020000140 R09: 0000000000000000
> > R10: 0000000020001100 R11: 0000000000000246 R12: 00007f49918876d4
> > R13: 00000000004c7d88 R14: 00000000004ce348 R15: 00000000ffffffff
> >
> > Uninit was stored to memory at:
> > kmsan_save_stack_with_flags mm/kmsan/kmsan.c:246 [inline]
> > kmsan_save_stack mm/kmsan/kmsan.c:261 [inline]
> > kmsan_internal_chain_origin+0x13d/0x240 mm/kmsan/kmsan.c:469
> > kmsan_memcpy_memmove_metadata+0x1a9/0xf70 mm/kmsan/kmsan.c:344
> > kmsan_memcpy_metadata+0xb/0x10 mm/kmsan/kmsan.c:362
> > __msan_memcpy+0x61/0x70 mm/kmsan/kmsan_instr.c:162
> > sctp_copy_laddrs net/sctp/socket.c:5901 [inline]
> > sctp_getsockopt_local_addrs net/sctp/socket.c:5967 [inline]
> > sctp_getsockopt+0x14f41/0x186f0 net/sctp/socket.c:7477
> > sock_common_getsockopt+0x13f/0x180 net/core/sock.c:2937
> > __sys_getsockopt+0x489/0x550 net/socket.c:1939
> > __do_sys_getsockopt net/socket.c:1950 [inline]
> > __se_sys_getsockopt+0xe1/0x100 net/socket.c:1947
> > __x64_sys_getsockopt+0x62/0x80 net/socket.c:1947
> > do_syscall_64+0xcf/0x110 arch/x86/entry/common.c:291
> > entry_SYSCALL_64_after_hwframe+0x63/0xe7
> >
> > Uninit was stored to memory at:
> > kmsan_save_stack_with_flags mm/kmsan/kmsan.c:246 [inline]
> > kmsan_save_stack mm/kmsan/kmsan.c:261 [inline]
> > kmsan_internal_chain_origin+0x13d/0x240 mm/kmsan/kmsan.c:469
> > kmsan_memcpy_memmove_metadata+0x1a9/0xf70 mm/kmsan/kmsan.c:344
> > kmsan_memcpy_metadata+0xb/0x10 mm/kmsan/kmsan.c:362
> > __msan_memcpy+0x61/0x70 mm/kmsan/kmsan_instr.c:162
> > sctp_copy_laddrs net/sctp/socket.c:5890 [inline]
> > sctp_getsockopt_local_addrs net/sctp/socket.c:5967 [inline]
> > sctp_getsockopt+0x14de8/0x186f0 net/sctp/socket.c:7477
> > sock_common_getsockopt+0x13f/0x180 net/core/sock.c:2937
> > __sys_getsockopt+0x489/0x550 net/socket.c:1939
> > __do_sys_getsockopt net/socket.c:1950 [inline]
> > __se_sys_getsockopt+0xe1/0x100 net/socket.c:1947
> > __x64_sys_getsockopt+0x62/0x80 net/socket.c:1947
> > do_syscall_64+0xcf/0x110 arch/x86/entry/common.c:291
> > entry_SYSCALL_64_after_hwframe+0x63/0xe7
> >
> > Uninit was created at:
> > kmsan_save_stack_with_flags mm/kmsan/kmsan.c:246 [inline]
> > kmsan_internal_poison_shadow+0x6d/0x130 mm/kmsan/kmsan.c:170
> > kmsan_kmalloc+0xa1/0x100 mm/kmsan/kmsan_hooks.c:186
> > __kmalloc+0x14c/0x4d0 mm/slub.c:3825
> > kmalloc include/linux/slab.h:551 [inline]
> > sctp_inet6addr_event+0x60e/0xbd0 net/sctp/ipv6.c:100
> > notifier_call_chain kernel/notifier.c:93 [inline]
> > __atomic_notifier_call_chain kernel/notifier.c:183 [inline]
> > atomic_notifier_call_chain+0x13d/0x240 kernel/notifier.c:193
> > inet6addr_notifier_call_chain+0x76/0x90 net/ipv6/addrconf_core.c:107
> > ipv6_add_addr+0x2597/0x2890 net/ipv6/addrconf.c:1115
> > inet6_addr_add+0xc86/0x1c10 net/ipv6/addrconf.c:2912
> > inet6_rtm_newaddr+0x167e/0x3d20 net/ipv6/addrconf.c:4750
> > rtnetlink_rcv_msg+0x1148/0x1540 net/core/rtnetlink.c:4947
> > netlink_rcv_skb+0x394/0x640 net/netlink/af_netlink.c:2477
> > rtnetlink_rcv+0x50/0x60 net/core/rtnetlink.c:4965
> > netlink_unicast_kernel net/netlink/af_netlink.c:1310 [inline]
> > netlink_unicast+0x1699/0x1740 net/netlink/af_netlink.c:1336
> > netlink_sendmsg+0x13c7/0x1440 net/netlink/af_netlink.c:1917
> > sock_sendmsg_nosec net/socket.c:621 [inline]
> > sock_sendmsg net/socket.c:631 [inline]
> > ___sys_sendmsg+0xe3b/0x1240 net/socket.c:2116
> > __sys_sendmsg net/socket.c:2154 [inline]
> > __do_sys_sendmsg net/socket.c:2163 [inline]
> > __se_sys_sendmsg+0x305/0x460 net/socket.c:2161
> > __x64_sys_sendmsg+0x4a/0x70 net/socket.c:2161
> > do_syscall_64+0xcf/0x110 arch/x86/entry/common.c:291
> > entry_SYSCALL_64_after_hwframe+0x63/0xe7
> >
> > Bytes 32-35 of 2100 are uninitialized
> > Memory access of size 2100 starts at ffff888185d8b000
> > Data copied to user address 0000000020001108
> > ==================================================================
> When a network device goes up and sctp_inetaddr_event() is called, it
> allocates a partially initialized struct sctp_sockaddr_entry to hold
> the newly created address.
> The attached reproducer can be then used to read up to 8 uninit bytes
> for each of the local addresses.
> I guess the devices aren't created so often that this can pose any
> security risk, but we probably still need to allocate this structure
> with __GFP_ZERO.
Agree. Thanks Alexander.
Looks like this is the last/only place left with this issue.
> >
> > ---
> > This bug is generated by a bot. It may contain errors.
> > See https://goo.gl/tpsmEJ for more information about syzbot.
> > syzbot engineers can be reached at syzkaller@googlegroups.com.
> >
> > syzbot will keep track of this bug report. See:
> > https://goo.gl/tpsmEJ#bug-status-tracking for how to communicate with
> > syzbot.
> > syzbot can test patches for this bug, for details see:
> > https://goo.gl/tpsmEJ#testing-patches
> >
> > --
> > You received this message because you are subscribed to the Google Groups "syzkaller-bugs" group.
> > To unsubscribe from this group and stop receiving emails from it, send an email to syzkaller-bugs+unsubscribe@googlegroups.com.
> > To view this discussion on the web visit https://groups.google.com/d/msgid/syzkaller-bugs/000000000000311344057c4b6cc3%40google.com.
> > For more options, visit https://groups.google.com/d/optout.
>
>
>
> --
> Alexander Potapenko
> Software Engineer
>
> Google Germany GmbH
> Erika-Mann-Straße, 33
> 80636 München
>
> Geschäftsführer: Paul Manicle, Halimah DeLaine Prado
> Registergericht und -nummer: Hamburg, HRB 86891
> Sitz der Gesellschaft: Hamburg
> #ifndef DUMP_BUF_H
> #define DUMP_BUF_H
>
> #ifndef DUMP_MIN_STRLEN
> #define DUMP_MIN_STRLEN 1
> #endif
>
> #ifndef DUMP_PARALLEL
> #define DUMP_PARALLEL 0
> #endif
>
> #ifndef DUMP_PRINT_BUF_ADDR
> #define DUMP_PRINT_BUF_ADDR 0
> #endif
>
> #ifndef DUMP_PRINT_HEX
> #define DUMP_PRINT_HEX 0
> #endif
>
> #ifndef DUMP_PRINT_STRING
> #define DUMP_PRINT_STRING 0
> #endif
>
> #if DUMP_PARALLEL
> pthread_mutex_t out_mutex = PTHREAD_MUTEX_INITIALIZER;
> #endif
>
> void dump_buf(unsigned char *buf, int len) {
> int i, nz = 0;
> for (i = 0; i < len; i++) {
> if (buf[i]) {
> nz = 1;
> break;
> }
> }
> if (!nz) {
> // The buffer is empty.
> return;
> } else {
> #if DUMP_PARALLEL
> pthread_mutex_lock(&out_mutex);
> #endif
> #if DUMP_PRINT_BUF_ADDR
> fprintf(stderr, "nonempty buffer at %p\n", buf);
> #endif
> #if DUMP_PRINT_HEX
> for (i=0; i < len; i++) {
> if (buf[i]) {
> fprintf(stderr, "buf[%d]: %x (%p)\n", i, buf[i], *(void**)&buf[i]);
> }
> }
> #endif // DUMP_PRINT_HEX
> #if DUMP_PARALLEL
> pthread_mutex_unlock(&out_mutex);
> #endif
> }
> #if DUMP_PARALLEL
> pthread_mutex_lock(&out_mutex);
> #endif
> #if DUMP_PRINT_STRING
> for (i = 0; i < len; i++) {
> if (buf[i]) {
> int str_len = strlen(&buf[i]);
> // Short string pieces are too boring.
> if (str_len >= DUMP_MIN_STRLEN) {
> unsigned char *c;
> for (c = &buf[i]; c < &buf[i + str_len]; c++) {
> if ((*c > 127) || ((*c < 32) && (*c != 10) && (*c != 13))) {
> *c = ' ';
> continue;
> }
> }
> // Dump the buffer.
> fprintf(stderr, "%s\n", &buf[i]);
> }
> i += str_len;
> }
> }
> #endif // DUMP_PRINT_STRING
> #if DUMP_PARALLEL
> pthread_mutex_unlock(&out_mutex);
> #endif
> }
>
> #endif
> #include <stdio.h>
> #include <pthread.h>
> #include <sys/types.h> /* See NOTES */
> #include <sys/socket.h>
> #include <unistd.h>
>
> #define DUMP_PARALLEL 1
> #define DUMP_PRINT_BUF_ADDR 1
> #define DUMP_PRINT_STRING 1
> #define DUMP_PRINT_HEX 1
> #include "dump_buf.h"
>
> void *setsockopt_fn(void *arg) {
> int sock = (int)arg;
> struct sockaddr addr;
> memset(&addr, 0, sizeof(addr));
> addr.sa_family = 2;
> addr.sa_data[2] = 0xac;
> addr.sa_data[3] = 0x14;
> addr.sa_data[4] = 0x14;
> setsockopt(sock, 0x84, 0x6e, &addr, 0x10);
> }
>
> #define BUFLEN (0x2c2)
> void *getsockopt_fn(void *arg) {
> int sock = (int)arg;
> char buf[BUFLEN];
> memset(buf, 0, BUFLEN);
> int socklen = BUFLEN;
> getsockopt(sock, 0x84, /*SCTP_GET_LOCAL_ADDRS*/0x6d, buf, &socklen);
> dump_buf(&(buf[8]), 32);
> }
>
> void do_work(int sock) {
> pthread_t t1, t2;
> for (int i = 0; i < 10; i++) {
> pthread_create(&t1, NULL, getsockopt_fn, (void*)sock);
> pthread_create(&t2, NULL, setsockopt_fn, (void*)sock);
> usleep(100);
> }
> }
>
> int main(int argc, char *argv[]) {
> int res;
> int pid = fork();
> if (pid == 0) {
> int sock = socket(0x2, 0x1, 0x84);
> do_work(sock);
> }
> sleep(10);
> return 0;
> }
^ permalink raw reply [flat|nested] 9+ messages in thread
* Re: KMSAN: kernel-infoleak in sctp_getsockopt
2018-12-06 11:06 ` Marcelo Ricardo Leitner
@ 2018-12-06 11:35 ` Alexander Potapenko
2018-12-10 8:56 ` Xin Long
1 sibling, 0 replies; 9+ messages in thread
From: Alexander Potapenko @ 2018-12-06 11:35 UTC (permalink / raw)
To: Marcelo Ricardo Leitner
Cc: syzbot+ad5d327e6936a2e284be, David Miller, LKML, linux-sctp,
Networking, nhorman, syzkaller-bugs, Vladislav Yasevich
On Thu, Dec 6, 2018 at 12:06 PM Marcelo Ricardo Leitner
<marcelo.leitner@gmail.com> wrote:
>
> On Thu, Dec 06, 2018 at 11:36:08AM +0100, Alexander Potapenko wrote:
> > On Wed, Dec 5, 2018 at 8:31 PM syzbot
> > <syzbot+ad5d327e6936a2e284be@syzkaller.appspotmail.com> wrote:
> > >
> > > Hello,
> > >
> > > syzbot found the following crash on:
> > >
> > > HEAD commit: fffec98ae2a6 net: proper support for CONFIG_GENERIC_CSUM o..
> > > git tree: https://github.com/google/kmsan.git/master
> > > console output: https://syzkaller.appspot.com/x/log.txt?x=12e84a47400000
> > > kernel config: https://syzkaller.appspot.com/x/.config?x=56b48b46dafe4516
> > > dashboard link: https://syzkaller.appspot.com/bug?extid=ad5d327e6936a2e284be
> > > compiler: clang version 8.0.0 (trunk 343298)
> > > syz repro: https://syzkaller.appspot.com/x/repro.syz?x=103cd225400000
> > >
> > > IMPORTANT: if you fix the bug, please add the following tag to the commit:
> > > Reported-by: syzbot+ad5d327e6936a2e284be@syzkaller.appspotmail.com
> > >
> > > 8021q: adding VLAN 0 to HW filter on device team0
> > > 8021q: adding VLAN 0 to HW filter on device team0
> > > 8021q: adding VLAN 0 to HW filter on device team0
> > > 8021q: adding VLAN 0 to HW filter on device team0
> > > ==================================================================
> > > BUG: KMSAN: kernel-infoleak in _copy_to_user+0x19a/0x230 lib/usercopy.c:33
> > > CPU: 1 PID: 8164 Comm: syz-executor2 Not tainted 4.20.0-rc3+ #95
> > > Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS
> > > Google 01/01/2011
> > > Call Trace:
> > > __dump_stack lib/dump_stack.c:77 [inline]
> > > dump_stack+0x32d/0x480 lib/dump_stack.c:113
> > > kmsan_report+0x12c/0x290 mm/kmsan/kmsan.c:683
> > > kmsan_internal_check_memory+0x32a/0xa50 mm/kmsan/kmsan.c:743
> > > kmsan_copy_to_user+0x78/0xd0 mm/kmsan/kmsan_hooks.c:634
> > > _copy_to_user+0x19a/0x230 lib/usercopy.c:33
> > > copy_to_user include/linux/uaccess.h:183 [inline]
> > > sctp_getsockopt_local_addrs net/sctp/socket.c:5998 [inline]
> > > sctp_getsockopt+0x15248/0x186f0 net/sctp/socket.c:7477
> > > sock_common_getsockopt+0x13f/0x180 net/core/sock.c:2937
> > > __sys_getsockopt+0x489/0x550 net/socket.c:1939
> > > __do_sys_getsockopt net/socket.c:1950 [inline]
> > > __se_sys_getsockopt+0xe1/0x100 net/socket.c:1947
> > > __x64_sys_getsockopt+0x62/0x80 net/socket.c:1947
> > > do_syscall_64+0xcf/0x110 arch/x86/entry/common.c:291
> > > entry_SYSCALL_64_after_hwframe+0x63/0xe7
> > > RIP: 0033:0x457569
> > > Code: fd b3 fb ff c3 66 2e 0f 1f 84 00 00 00 00 00 66 90 48 89 f8 48 89 f7
> > > 48 89 d6 48 89 ca 4d 89 c2 4d 89 c8 4c 8b 4c 24 08 0f 05 <48> 3d 01 f0 ff
> > > ff 0f 83 cb b3 fb ff c3 66 2e 0f 1f 84 00 00 00 00
> > > RSP: 002b:00007f4991886c78 EFLAGS: 00000246 ORIG_RAX: 0000000000000037
> > > RAX: ffffffffffffffda RBX: 0000000000000005 RCX: 0000000000457569
> > > RDX: 000000000000006d RSI: 0000000000000084 RDI: 0000000000000003
> > > RBP: 000000000072bf00 R08: 0000000020000140 R09: 0000000000000000
> > > R10: 0000000020001100 R11: 0000000000000246 R12: 00007f49918876d4
> > > R13: 00000000004c7d88 R14: 00000000004ce348 R15: 00000000ffffffff
> > >
> > > Uninit was stored to memory at:
> > > kmsan_save_stack_with_flags mm/kmsan/kmsan.c:246 [inline]
> > > kmsan_save_stack mm/kmsan/kmsan.c:261 [inline]
> > > kmsan_internal_chain_origin+0x13d/0x240 mm/kmsan/kmsan.c:469
> > > kmsan_memcpy_memmove_metadata+0x1a9/0xf70 mm/kmsan/kmsan.c:344
> > > kmsan_memcpy_metadata+0xb/0x10 mm/kmsan/kmsan.c:362
> > > __msan_memcpy+0x61/0x70 mm/kmsan/kmsan_instr.c:162
> > > sctp_copy_laddrs net/sctp/socket.c:5901 [inline]
> > > sctp_getsockopt_local_addrs net/sctp/socket.c:5967 [inline]
> > > sctp_getsockopt+0x14f41/0x186f0 net/sctp/socket.c:7477
> > > sock_common_getsockopt+0x13f/0x180 net/core/sock.c:2937
> > > __sys_getsockopt+0x489/0x550 net/socket.c:1939
> > > __do_sys_getsockopt net/socket.c:1950 [inline]
> > > __se_sys_getsockopt+0xe1/0x100 net/socket.c:1947
> > > __x64_sys_getsockopt+0x62/0x80 net/socket.c:1947
> > > do_syscall_64+0xcf/0x110 arch/x86/entry/common.c:291
> > > entry_SYSCALL_64_after_hwframe+0x63/0xe7
> > >
> > > Uninit was stored to memory at:
> > > kmsan_save_stack_with_flags mm/kmsan/kmsan.c:246 [inline]
> > > kmsan_save_stack mm/kmsan/kmsan.c:261 [inline]
> > > kmsan_internal_chain_origin+0x13d/0x240 mm/kmsan/kmsan.c:469
> > > kmsan_memcpy_memmove_metadata+0x1a9/0xf70 mm/kmsan/kmsan.c:344
> > > kmsan_memcpy_metadata+0xb/0x10 mm/kmsan/kmsan.c:362
> > > __msan_memcpy+0x61/0x70 mm/kmsan/kmsan_instr.c:162
> > > sctp_copy_laddrs net/sctp/socket.c:5890 [inline]
> > > sctp_getsockopt_local_addrs net/sctp/socket.c:5967 [inline]
> > > sctp_getsockopt+0x14de8/0x186f0 net/sctp/socket.c:7477
> > > sock_common_getsockopt+0x13f/0x180 net/core/sock.c:2937
> > > __sys_getsockopt+0x489/0x550 net/socket.c:1939
> > > __do_sys_getsockopt net/socket.c:1950 [inline]
> > > __se_sys_getsockopt+0xe1/0x100 net/socket.c:1947
> > > __x64_sys_getsockopt+0x62/0x80 net/socket.c:1947
> > > do_syscall_64+0xcf/0x110 arch/x86/entry/common.c:291
> > > entry_SYSCALL_64_after_hwframe+0x63/0xe7
> > >
> > > Uninit was created at:
> > > kmsan_save_stack_with_flags mm/kmsan/kmsan.c:246 [inline]
> > > kmsan_internal_poison_shadow+0x6d/0x130 mm/kmsan/kmsan.c:170
> > > kmsan_kmalloc+0xa1/0x100 mm/kmsan/kmsan_hooks.c:186
> > > __kmalloc+0x14c/0x4d0 mm/slub.c:3825
> > > kmalloc include/linux/slab.h:551 [inline]
> > > sctp_inet6addr_event+0x60e/0xbd0 net/sctp/ipv6.c:100
> > > notifier_call_chain kernel/notifier.c:93 [inline]
> > > __atomic_notifier_call_chain kernel/notifier.c:183 [inline]
> > > atomic_notifier_call_chain+0x13d/0x240 kernel/notifier.c:193
> > > inet6addr_notifier_call_chain+0x76/0x90 net/ipv6/addrconf_core.c:107
> > > ipv6_add_addr+0x2597/0x2890 net/ipv6/addrconf.c:1115
> > > inet6_addr_add+0xc86/0x1c10 net/ipv6/addrconf.c:2912
> > > inet6_rtm_newaddr+0x167e/0x3d20 net/ipv6/addrconf.c:4750
> > > rtnetlink_rcv_msg+0x1148/0x1540 net/core/rtnetlink.c:4947
> > > netlink_rcv_skb+0x394/0x640 net/netlink/af_netlink.c:2477
> > > rtnetlink_rcv+0x50/0x60 net/core/rtnetlink.c:4965
> > > netlink_unicast_kernel net/netlink/af_netlink.c:1310 [inline]
> > > netlink_unicast+0x1699/0x1740 net/netlink/af_netlink.c:1336
> > > netlink_sendmsg+0x13c7/0x1440 net/netlink/af_netlink.c:1917
> > > sock_sendmsg_nosec net/socket.c:621 [inline]
> > > sock_sendmsg net/socket.c:631 [inline]
> > > ___sys_sendmsg+0xe3b/0x1240 net/socket.c:2116
> > > __sys_sendmsg net/socket.c:2154 [inline]
> > > __do_sys_sendmsg net/socket.c:2163 [inline]
> > > __se_sys_sendmsg+0x305/0x460 net/socket.c:2161
> > > __x64_sys_sendmsg+0x4a/0x70 net/socket.c:2161
> > > do_syscall_64+0xcf/0x110 arch/x86/entry/common.c:291
> > > entry_SYSCALL_64_after_hwframe+0x63/0xe7
> > >
> > > Bytes 32-35 of 2100 are uninitialized
> > > Memory access of size 2100 starts at ffff888185d8b000
> > > Data copied to user address 0000000020001108
> > > ==================================================================
> > When a network device goes up and sctp_inetaddr_event() is called, it
> > allocates a partially initialized struct sctp_sockaddr_entry to hold
> > the newly created address.
> > The attached reproducer can be then used to read up to 8 uninit bytes
> > for each of the local addresses.
> > I guess the devices aren't created so often that this can pose any
> > security risk, but we probably still need to allocate this structure
> > with __GFP_ZERO.
>
> Agree. Thanks Alexander.
> Looks like this is the last/only place left with this issue.
It also turns out that a non-privileged user is allowed to create
network devices within a namespace, which makes it easier to generate
more uninitialized data.
> > >
> > > ---
> > > This bug is generated by a bot. It may contain errors.
> > > See https://goo.gl/tpsmEJ for more information about syzbot.
> > > syzbot engineers can be reached at syzkaller@googlegroups.com.
> > >
> > > syzbot will keep track of this bug report. See:
> > > https://goo.gl/tpsmEJ#bug-status-tracking for how to communicate with
> > > syzbot.
> > > syzbot can test patches for this bug, for details see:
> > > https://goo.gl/tpsmEJ#testing-patches
> > >
> > > --
> > > You received this message because you are subscribed to the Google Groups "syzkaller-bugs" group.
> > > To unsubscribe from this group and stop receiving emails from it, send an email to syzkaller-bugs+unsubscribe@googlegroups.com.
> > > To view this discussion on the web visit https://groups.google.com/d/msgid/syzkaller-bugs/000000000000311344057c4b6cc3%40google.com.
> > > For more options, visit https://groups.google.com/d/optout.
> >
> >
> >
> > --
> > Alexander Potapenko
> > Software Engineer
> >
> > Google Germany GmbH
> > Erika-Mann-Straße, 33
> > 80636 München
> >
> > Geschäftsführer: Paul Manicle, Halimah DeLaine Prado
> > Registergericht und -nummer: Hamburg, HRB 86891
> > Sitz der Gesellschaft: Hamburg
>
> > #ifndef DUMP_BUF_H
> > #define DUMP_BUF_H
> >
> > #ifndef DUMP_MIN_STRLEN
> > #define DUMP_MIN_STRLEN 1
> > #endif
> >
> > #ifndef DUMP_PARALLEL
> > #define DUMP_PARALLEL 0
> > #endif
> >
> > #ifndef DUMP_PRINT_BUF_ADDR
> > #define DUMP_PRINT_BUF_ADDR 0
> > #endif
> >
> > #ifndef DUMP_PRINT_HEX
> > #define DUMP_PRINT_HEX 0
> > #endif
> >
> > #ifndef DUMP_PRINT_STRING
> > #define DUMP_PRINT_STRING 0
> > #endif
> >
> > #if DUMP_PARALLEL
> > pthread_mutex_t out_mutex = PTHREAD_MUTEX_INITIALIZER;
> > #endif
> >
> > void dump_buf(unsigned char *buf, int len) {
> > int i, nz = 0;
> > for (i = 0; i < len; i++) {
> > if (buf[i]) {
> > nz = 1;
> > break;
> > }
> > }
> > if (!nz) {
> > // The buffer is empty.
> > return;
> > } else {
> > #if DUMP_PARALLEL
> > pthread_mutex_lock(&out_mutex);
> > #endif
> > #if DUMP_PRINT_BUF_ADDR
> > fprintf(stderr, "nonempty buffer at %p\n", buf);
> > #endif
> > #if DUMP_PRINT_HEX
> > for (i=0; i < len; i++) {
> > if (buf[i]) {
> > fprintf(stderr, "buf[%d]: %x (%p)\n", i, buf[i], *(void**)&buf[i]);
> > }
> > }
> > #endif // DUMP_PRINT_HEX
> > #if DUMP_PARALLEL
> > pthread_mutex_unlock(&out_mutex);
> > #endif
> > }
> > #if DUMP_PARALLEL
> > pthread_mutex_lock(&out_mutex);
> > #endif
> > #if DUMP_PRINT_STRING
> > for (i = 0; i < len; i++) {
> > if (buf[i]) {
> > int str_len = strlen(&buf[i]);
> > // Short string pieces are too boring.
> > if (str_len >= DUMP_MIN_STRLEN) {
> > unsigned char *c;
> > for (c = &buf[i]; c < &buf[i + str_len]; c++) {
> > if ((*c > 127) || ((*c < 32) && (*c != 10) && (*c != 13))) {
> > *c = ' ';
> > continue;
> > }
> > }
> > // Dump the buffer.
> > fprintf(stderr, "%s\n", &buf[i]);
> > }
> > i += str_len;
> > }
> > }
> > #endif // DUMP_PRINT_STRING
> > #if DUMP_PARALLEL
> > pthread_mutex_unlock(&out_mutex);
> > #endif
> > }
> >
> > #endif
>
> > #include <stdio.h>
> > #include <pthread.h>
> > #include <sys/types.h> /* See NOTES */
> > #include <sys/socket.h>
> > #include <unistd.h>
> >
> > #define DUMP_PARALLEL 1
> > #define DUMP_PRINT_BUF_ADDR 1
> > #define DUMP_PRINT_STRING 1
> > #define DUMP_PRINT_HEX 1
> > #include "dump_buf.h"
> >
> > void *setsockopt_fn(void *arg) {
> > int sock = (int)arg;
> > struct sockaddr addr;
> > memset(&addr, 0, sizeof(addr));
> > addr.sa_family = 2;
> > addr.sa_data[2] = 0xac;
> > addr.sa_data[3] = 0x14;
> > addr.sa_data[4] = 0x14;
> > setsockopt(sock, 0x84, 0x6e, &addr, 0x10);
> > }
> >
> > #define BUFLEN (0x2c2)
> > void *getsockopt_fn(void *arg) {
> > int sock = (int)arg;
> > char buf[BUFLEN];
> > memset(buf, 0, BUFLEN);
> > int socklen = BUFLEN;
> > getsockopt(sock, 0x84, /*SCTP_GET_LOCAL_ADDRS*/0x6d, buf, &socklen);
> > dump_buf(&(buf[8]), 32);
> > }
> >
> > void do_work(int sock) {
> > pthread_t t1, t2;
> > for (int i = 0; i < 10; i++) {
> > pthread_create(&t1, NULL, getsockopt_fn, (void*)sock);
> > pthread_create(&t2, NULL, setsockopt_fn, (void*)sock);
> > usleep(100);
> > }
> > }
> >
> > int main(int argc, char *argv[]) {
> > int res;
> > int pid = fork();
> > if (pid == 0) {
> > int sock = socket(0x2, 0x1, 0x84);
> > do_work(sock);
> > }
> > sleep(10);
> > return 0;
> > }
>
--
Alexander Potapenko
Software Engineer
Google Germany GmbH
Erika-Mann-Straße, 33
80636 München
Geschäftsführer: Paul Manicle, Halimah DeLaine Prado
Registergericht und -nummer: Hamburg, HRB 86891
Sitz der Gesellschaft: Hamburg
^ permalink raw reply [flat|nested] 9+ messages in thread
* Re: KMSAN: kernel-infoleak in sctp_getsockopt
2018-12-06 11:06 ` Marcelo Ricardo Leitner
2018-12-06 11:35 ` Alexander Potapenko
@ 2018-12-10 8:56 ` Xin Long
2019-01-14 9:34 ` Alexander Potapenko
1 sibling, 1 reply; 9+ messages in thread
From: Xin Long @ 2018-12-10 8:56 UTC (permalink / raw)
To: Marcelo Ricardo Leitner
Cc: Alexander Potapenko, syzbot+ad5d327e6936a2e284be, davem, LKML,
linux-sctp, network dev, Neil Horman, syzkaller-bugs,
Vlad Yasevich
On Thu, Dec 6, 2018 at 8:08 PM Marcelo Ricardo Leitner
<marcelo.leitner@gmail.com> wrote:
>
> On Thu, Dec 06, 2018 at 11:36:08AM +0100, Alexander Potapenko wrote:
> > On Wed, Dec 5, 2018 at 8:31 PM syzbot
> > <syzbot+ad5d327e6936a2e284be@syzkaller.appspotmail.com> wrote:
> > >
> > > Hello,
> > >
> > > syzbot found the following crash on:
> > >
> > > HEAD commit: fffec98ae2a6 net: proper support for CONFIG_GENERIC_CSUM o..
> > > git tree: https://github.com/google/kmsan.git/master
> > > console output: https://syzkaller.appspot.com/x/log.txt?x=12e84a47400000
> > > kernel config: https://syzkaller.appspot.com/x/.config?x=56b48b46dafe4516
> > > dashboard link: https://syzkaller.appspot.com/bug?extid=ad5d327e6936a2e284be
> > > compiler: clang version 8.0.0 (trunk 343298)
> > > syz repro: https://syzkaller.appspot.com/x/repro.syz?x=103cd225400000
> > >
> > > IMPORTANT: if you fix the bug, please add the following tag to the commit:
> > > Reported-by: syzbot+ad5d327e6936a2e284be@syzkaller.appspotmail.com
> > >
> > > 8021q: adding VLAN 0 to HW filter on device team0
> > > 8021q: adding VLAN 0 to HW filter on device team0
> > > 8021q: adding VLAN 0 to HW filter on device team0
> > > 8021q: adding VLAN 0 to HW filter on device team0
> > > ==================================================================
> > > BUG: KMSAN: kernel-infoleak in _copy_to_user+0x19a/0x230 lib/usercopy.c:33
> > > CPU: 1 PID: 8164 Comm: syz-executor2 Not tainted 4.20.0-rc3+ #95
> > > Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS
> > > Google 01/01/2011
> > > Call Trace:
> > > __dump_stack lib/dump_stack.c:77 [inline]
> > > dump_stack+0x32d/0x480 lib/dump_stack.c:113
> > > kmsan_report+0x12c/0x290 mm/kmsan/kmsan.c:683
> > > kmsan_internal_check_memory+0x32a/0xa50 mm/kmsan/kmsan.c:743
> > > kmsan_copy_to_user+0x78/0xd0 mm/kmsan/kmsan_hooks.c:634
> > > _copy_to_user+0x19a/0x230 lib/usercopy.c:33
> > > copy_to_user include/linux/uaccess.h:183 [inline]
> > > sctp_getsockopt_local_addrs net/sctp/socket.c:5998 [inline]
> > > sctp_getsockopt+0x15248/0x186f0 net/sctp/socket.c:7477
> > > sock_common_getsockopt+0x13f/0x180 net/core/sock.c:2937
> > > __sys_getsockopt+0x489/0x550 net/socket.c:1939
> > > __do_sys_getsockopt net/socket.c:1950 [inline]
> > > __se_sys_getsockopt+0xe1/0x100 net/socket.c:1947
> > > __x64_sys_getsockopt+0x62/0x80 net/socket.c:1947
> > > do_syscall_64+0xcf/0x110 arch/x86/entry/common.c:291
> > > entry_SYSCALL_64_after_hwframe+0x63/0xe7
> > > RIP: 0033:0x457569
> > > Code: fd b3 fb ff c3 66 2e 0f 1f 84 00 00 00 00 00 66 90 48 89 f8 48 89 f7
> > > 48 89 d6 48 89 ca 4d 89 c2 4d 89 c8 4c 8b 4c 24 08 0f 05 <48> 3d 01 f0 ff
> > > ff 0f 83 cb b3 fb ff c3 66 2e 0f 1f 84 00 00 00 00
> > > RSP: 002b:00007f4991886c78 EFLAGS: 00000246 ORIG_RAX: 0000000000000037
> > > RAX: ffffffffffffffda RBX: 0000000000000005 RCX: 0000000000457569
> > > RDX: 000000000000006d RSI: 0000000000000084 RDI: 0000000000000003
> > > RBP: 000000000072bf00 R08: 0000000020000140 R09: 0000000000000000
> > > R10: 0000000020001100 R11: 0000000000000246 R12: 00007f49918876d4
> > > R13: 00000000004c7d88 R14: 00000000004ce348 R15: 00000000ffffffff
> > >
> > > Uninit was stored to memory at:
> > > kmsan_save_stack_with_flags mm/kmsan/kmsan.c:246 [inline]
> > > kmsan_save_stack mm/kmsan/kmsan.c:261 [inline]
> > > kmsan_internal_chain_origin+0x13d/0x240 mm/kmsan/kmsan.c:469
> > > kmsan_memcpy_memmove_metadata+0x1a9/0xf70 mm/kmsan/kmsan.c:344
> > > kmsan_memcpy_metadata+0xb/0x10 mm/kmsan/kmsan.c:362
> > > __msan_memcpy+0x61/0x70 mm/kmsan/kmsan_instr.c:162
> > > sctp_copy_laddrs net/sctp/socket.c:5901 [inline]
> > > sctp_getsockopt_local_addrs net/sctp/socket.c:5967 [inline]
> > > sctp_getsockopt+0x14f41/0x186f0 net/sctp/socket.c:7477
> > > sock_common_getsockopt+0x13f/0x180 net/core/sock.c:2937
> > > __sys_getsockopt+0x489/0x550 net/socket.c:1939
> > > __do_sys_getsockopt net/socket.c:1950 [inline]
> > > __se_sys_getsockopt+0xe1/0x100 net/socket.c:1947
> > > __x64_sys_getsockopt+0x62/0x80 net/socket.c:1947
> > > do_syscall_64+0xcf/0x110 arch/x86/entry/common.c:291
> > > entry_SYSCALL_64_after_hwframe+0x63/0xe7
> > >
> > > Uninit was stored to memory at:
> > > kmsan_save_stack_with_flags mm/kmsan/kmsan.c:246 [inline]
> > > kmsan_save_stack mm/kmsan/kmsan.c:261 [inline]
> > > kmsan_internal_chain_origin+0x13d/0x240 mm/kmsan/kmsan.c:469
> > > kmsan_memcpy_memmove_metadata+0x1a9/0xf70 mm/kmsan/kmsan.c:344
> > > kmsan_memcpy_metadata+0xb/0x10 mm/kmsan/kmsan.c:362
> > > __msan_memcpy+0x61/0x70 mm/kmsan/kmsan_instr.c:162
> > > sctp_copy_laddrs net/sctp/socket.c:5890 [inline]
> > > sctp_getsockopt_local_addrs net/sctp/socket.c:5967 [inline]
> > > sctp_getsockopt+0x14de8/0x186f0 net/sctp/socket.c:7477
> > > sock_common_getsockopt+0x13f/0x180 net/core/sock.c:2937
> > > __sys_getsockopt+0x489/0x550 net/socket.c:1939
> > > __do_sys_getsockopt net/socket.c:1950 [inline]
> > > __se_sys_getsockopt+0xe1/0x100 net/socket.c:1947
> > > __x64_sys_getsockopt+0x62/0x80 net/socket.c:1947
> > > do_syscall_64+0xcf/0x110 arch/x86/entry/common.c:291
> > > entry_SYSCALL_64_after_hwframe+0x63/0xe7
> > >
> > > Uninit was created at:
> > > kmsan_save_stack_with_flags mm/kmsan/kmsan.c:246 [inline]
> > > kmsan_internal_poison_shadow+0x6d/0x130 mm/kmsan/kmsan.c:170
> > > kmsan_kmalloc+0xa1/0x100 mm/kmsan/kmsan_hooks.c:186
> > > __kmalloc+0x14c/0x4d0 mm/slub.c:3825
> > > kmalloc include/linux/slab.h:551 [inline]
> > > sctp_inet6addr_event+0x60e/0xbd0 net/sctp/ipv6.c:100
> > > notifier_call_chain kernel/notifier.c:93 [inline]
> > > __atomic_notifier_call_chain kernel/notifier.c:183 [inline]
> > > atomic_notifier_call_chain+0x13d/0x240 kernel/notifier.c:193
> > > inet6addr_notifier_call_chain+0x76/0x90 net/ipv6/addrconf_core.c:107
> > > ipv6_add_addr+0x2597/0x2890 net/ipv6/addrconf.c:1115
> > > inet6_addr_add+0xc86/0x1c10 net/ipv6/addrconf.c:2912
> > > inet6_rtm_newaddr+0x167e/0x3d20 net/ipv6/addrconf.c:4750
> > > rtnetlink_rcv_msg+0x1148/0x1540 net/core/rtnetlink.c:4947
> > > netlink_rcv_skb+0x394/0x640 net/netlink/af_netlink.c:2477
> > > rtnetlink_rcv+0x50/0x60 net/core/rtnetlink.c:4965
> > > netlink_unicast_kernel net/netlink/af_netlink.c:1310 [inline]
> > > netlink_unicast+0x1699/0x1740 net/netlink/af_netlink.c:1336
> > > netlink_sendmsg+0x13c7/0x1440 net/netlink/af_netlink.c:1917
> > > sock_sendmsg_nosec net/socket.c:621 [inline]
> > > sock_sendmsg net/socket.c:631 [inline]
> > > ___sys_sendmsg+0xe3b/0x1240 net/socket.c:2116
> > > __sys_sendmsg net/socket.c:2154 [inline]
> > > __do_sys_sendmsg net/socket.c:2163 [inline]
> > > __se_sys_sendmsg+0x305/0x460 net/socket.c:2161
> > > __x64_sys_sendmsg+0x4a/0x70 net/socket.c:2161
> > > do_syscall_64+0xcf/0x110 arch/x86/entry/common.c:291
> > > entry_SYSCALL_64_after_hwframe+0x63/0xe7
> > >
> > > Bytes 32-35 of 2100 are uninitialized
> > > Memory access of size 2100 starts at ffff888185d8b000
> > > Data copied to user address 0000000020001108
> > > ==================================================================
> > When a network device goes up and sctp_inetaddr_event() is called, it
> > allocates a partially initialized struct sctp_sockaddr_entry to hold
> > the newly created address.
> > The attached reproducer can be then used to read up to 8 uninit bytes
> > for each of the local addresses.
> > I guess the devices aren't created so often that this can pose any
> > security risk, but we probably still need to allocate this structure
> > with __GFP_ZERO.
>
> Agree. Thanks Alexander.
> Looks like this is the last/only place left with this issue.
This field is not really used by sctp, I will just set it to 0.
diff --git a/net/sctp/ipv6.c b/net/sctp/ipv6.c
index fc6c5e4bffa5..7f0539db5604 100644
--- a/net/sctp/ipv6.c
+++ b/net/sctp/ipv6.c
@@ -101,6 +101,7 @@ static int sctp_inet6addr_event(struct
notifier_block *this, unsigned long ev,
if (addr) {
addr->a.v6.sin6_family = AF_INET6;
addr->a.v6.sin6_port = 0;
+ addr->a.v6.sin6_flowinfo = 0;
addr->a.v6.sin6_addr = ifa->addr;
addr->a.v6.sin6_scope_id = ifa->idev->dev->ifindex;
addr->valid = 1;
>
> > >
> > > ---
> > > This bug is generated by a bot. It may contain errors.
> > > See https://goo.gl/tpsmEJ for more information about syzbot.
> > > syzbot engineers can be reached at syzkaller@googlegroups.com.
> > >
> > > syzbot will keep track of this bug report. See:
> > > https://goo.gl/tpsmEJ#bug-status-tracking for how to communicate with
> > > syzbot.
> > > syzbot can test patches for this bug, for details see:
> > > https://goo.gl/tpsmEJ#testing-patches
> > >
> > > --
> > > You received this message because you are subscribed to the Google Groups "syzkaller-bugs" group.
> > > To unsubscribe from this group and stop receiving emails from it, send an email to syzkaller-bugs+unsubscribe@googlegroups.com.
> > > To view this discussion on the web visit https://groups.google.com/d/msgid/syzkaller-bugs/000000000000311344057c4b6cc3%40google.com.
> > > For more options, visit https://groups.google.com/d/optout.
> >
> >
> >
> > --
> > Alexander Potapenko
> > Software Engineer
> >
> > Google Germany GmbH
> > Erika-Mann-Straße, 33
> > 80636 München
> >
> > Geschäftsführer: Paul Manicle, Halimah DeLaine Prado
> > Registergericht und -nummer: Hamburg, HRB 86891
> > Sitz der Gesellschaft: Hamburg
>
> > #ifndef DUMP_BUF_H
> > #define DUMP_BUF_H
> >
> > #ifndef DUMP_MIN_STRLEN
> > #define DUMP_MIN_STRLEN 1
> > #endif
> >
> > #ifndef DUMP_PARALLEL
> > #define DUMP_PARALLEL 0
> > #endif
> >
> > #ifndef DUMP_PRINT_BUF_ADDR
> > #define DUMP_PRINT_BUF_ADDR 0
> > #endif
> >
> > #ifndef DUMP_PRINT_HEX
> > #define DUMP_PRINT_HEX 0
> > #endif
> >
> > #ifndef DUMP_PRINT_STRING
> > #define DUMP_PRINT_STRING 0
> > #endif
> >
> > #if DUMP_PARALLEL
> > pthread_mutex_t out_mutex = PTHREAD_MUTEX_INITIALIZER;
> > #endif
> >
> > void dump_buf(unsigned char *buf, int len) {
> > int i, nz = 0;
> > for (i = 0; i < len; i++) {
> > if (buf[i]) {
> > nz = 1;
> > break;
> > }
> > }
> > if (!nz) {
> > // The buffer is empty.
> > return;
> > } else {
> > #if DUMP_PARALLEL
> > pthread_mutex_lock(&out_mutex);
> > #endif
> > #if DUMP_PRINT_BUF_ADDR
> > fprintf(stderr, "nonempty buffer at %p\n", buf);
> > #endif
> > #if DUMP_PRINT_HEX
> > for (i=0; i < len; i++) {
> > if (buf[i]) {
> > fprintf(stderr, "buf[%d]: %x (%p)\n", i, buf[i], *(void**)&buf[i]);
> > }
> > }
> > #endif // DUMP_PRINT_HEX
> > #if DUMP_PARALLEL
> > pthread_mutex_unlock(&out_mutex);
> > #endif
> > }
> > #if DUMP_PARALLEL
> > pthread_mutex_lock(&out_mutex);
> > #endif
> > #if DUMP_PRINT_STRING
> > for (i = 0; i < len; i++) {
> > if (buf[i]) {
> > int str_len = strlen(&buf[i]);
> > // Short string pieces are too boring.
> > if (str_len >= DUMP_MIN_STRLEN) {
> > unsigned char *c;
> > for (c = &buf[i]; c < &buf[i + str_len]; c++) {
> > if ((*c > 127) || ((*c < 32) && (*c != 10) && (*c != 13))) {
> > *c = ' ';
> > continue;
> > }
> > }
> > // Dump the buffer.
> > fprintf(stderr, "%s\n", &buf[i]);
> > }
> > i += str_len;
> > }
> > }
> > #endif // DUMP_PRINT_STRING
> > #if DUMP_PARALLEL
> > pthread_mutex_unlock(&out_mutex);
> > #endif
> > }
> >
> > #endif
>
> > #include <stdio.h>
> > #include <pthread.h>
> > #include <sys/types.h> /* See NOTES */
> > #include <sys/socket.h>
> > #include <unistd.h>
> >
> > #define DUMP_PARALLEL 1
> > #define DUMP_PRINT_BUF_ADDR 1
> > #define DUMP_PRINT_STRING 1
> > #define DUMP_PRINT_HEX 1
> > #include "dump_buf.h"
> >
> > void *setsockopt_fn(void *arg) {
> > int sock = (int)arg;
> > struct sockaddr addr;
> > memset(&addr, 0, sizeof(addr));
> > addr.sa_family = 2;
> > addr.sa_data[2] = 0xac;
> > addr.sa_data[3] = 0x14;
> > addr.sa_data[4] = 0x14;
> > setsockopt(sock, 0x84, 0x6e, &addr, 0x10);
> > }
> >
> > #define BUFLEN (0x2c2)
> > void *getsockopt_fn(void *arg) {
> > int sock = (int)arg;
> > char buf[BUFLEN];
> > memset(buf, 0, BUFLEN);
> > int socklen = BUFLEN;
> > getsockopt(sock, 0x84, /*SCTP_GET_LOCAL_ADDRS*/0x6d, buf, &socklen);
> > dump_buf(&(buf[8]), 32);
> > }
> >
> > void do_work(int sock) {
> > pthread_t t1, t2;
> > for (int i = 0; i < 10; i++) {
> > pthread_create(&t1, NULL, getsockopt_fn, (void*)sock);
> > pthread_create(&t2, NULL, setsockopt_fn, (void*)sock);
> > usleep(100);
> > }
> > }
> >
> > int main(int argc, char *argv[]) {
> > int res;
> > int pid = fork();
> > if (pid == 0) {
> > int sock = socket(0x2, 0x1, 0x84);
> > do_work(sock);
> > }
> > sleep(10);
> > return 0;
> > }
>
^ permalink raw reply related [flat|nested] 9+ messages in thread
* Re: KMSAN: kernel-infoleak in sctp_getsockopt
2018-12-10 8:56 ` Xin Long
@ 2019-01-14 9:34 ` Alexander Potapenko
2019-01-14 9:55 ` Xin Long
0 siblings, 1 reply; 9+ messages in thread
From: Alexander Potapenko @ 2019-01-14 9:34 UTC (permalink / raw)
To: Xin Long
Cc: Marcelo Ricardo Leitner, syzbot+ad5d327e6936a2e284be, davem,
LKML, linux-sctp, network dev, Neil Horman, syzkaller-bugs,
Vlad Yasevich
On Mon, Dec 10, 2018 at 9:56 AM Xin Long <lucien.xin@gmail.com> wrote:
>
> On Thu, Dec 6, 2018 at 8:08 PM Marcelo Ricardo Leitner
> <marcelo.leitner@gmail.com> wrote:
> >
> > On Thu, Dec 06, 2018 at 11:36:08AM +0100, Alexander Potapenko wrote:
> > > On Wed, Dec 5, 2018 at 8:31 PM syzbot
> > > <syzbot+ad5d327e6936a2e284be@syzkaller.appspotmail.com> wrote:
> > > >
> > > > Hello,
> > > >
> > > > syzbot found the following crash on:
> > > >
> > > > HEAD commit: fffec98ae2a6 net: proper support for CONFIG_GENERIC_CSUM o..
> > > > git tree: https://github.com/google/kmsan.git/master
> > > > console output: https://syzkaller.appspot.com/x/log.txt?x=12e84a47400000
> > > > kernel config: https://syzkaller.appspot.com/x/.config?x=56b48b46dafe4516
> > > > dashboard link: https://syzkaller.appspot.com/bug?extid=ad5d327e6936a2e284be
> > > > compiler: clang version 8.0.0 (trunk 343298)
> > > > syz repro: https://syzkaller.appspot.com/x/repro.syz?x=103cd225400000
> > > >
> > > > IMPORTANT: if you fix the bug, please add the following tag to the commit:
> > > > Reported-by: syzbot+ad5d327e6936a2e284be@syzkaller.appspotmail.com
> > > >
> > > > 8021q: adding VLAN 0 to HW filter on device team0
> > > > 8021q: adding VLAN 0 to HW filter on device team0
> > > > 8021q: adding VLAN 0 to HW filter on device team0
> > > > 8021q: adding VLAN 0 to HW filter on device team0
> > > > ==================================================================
> > > > BUG: KMSAN: kernel-infoleak in _copy_to_user+0x19a/0x230 lib/usercopy.c:33
> > > > CPU: 1 PID: 8164 Comm: syz-executor2 Not tainted 4.20.0-rc3+ #95
> > > > Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS
> > > > Google 01/01/2011
> > > > Call Trace:
> > > > __dump_stack lib/dump_stack.c:77 [inline]
> > > > dump_stack+0x32d/0x480 lib/dump_stack.c:113
> > > > kmsan_report+0x12c/0x290 mm/kmsan/kmsan.c:683
> > > > kmsan_internal_check_memory+0x32a/0xa50 mm/kmsan/kmsan.c:743
> > > > kmsan_copy_to_user+0x78/0xd0 mm/kmsan/kmsan_hooks.c:634
> > > > _copy_to_user+0x19a/0x230 lib/usercopy.c:33
> > > > copy_to_user include/linux/uaccess.h:183 [inline]
> > > > sctp_getsockopt_local_addrs net/sctp/socket.c:5998 [inline]
> > > > sctp_getsockopt+0x15248/0x186f0 net/sctp/socket.c:7477
> > > > sock_common_getsockopt+0x13f/0x180 net/core/sock.c:2937
> > > > __sys_getsockopt+0x489/0x550 net/socket.c:1939
> > > > __do_sys_getsockopt net/socket.c:1950 [inline]
> > > > __se_sys_getsockopt+0xe1/0x100 net/socket.c:1947
> > > > __x64_sys_getsockopt+0x62/0x80 net/socket.c:1947
> > > > do_syscall_64+0xcf/0x110 arch/x86/entry/common.c:291
> > > > entry_SYSCALL_64_after_hwframe+0x63/0xe7
> > > > RIP: 0033:0x457569
> > > > Code: fd b3 fb ff c3 66 2e 0f 1f 84 00 00 00 00 00 66 90 48 89 f8 48 89 f7
> > > > 48 89 d6 48 89 ca 4d 89 c2 4d 89 c8 4c 8b 4c 24 08 0f 05 <48> 3d 01 f0 ff
> > > > ff 0f 83 cb b3 fb ff c3 66 2e 0f 1f 84 00 00 00 00
> > > > RSP: 002b:00007f4991886c78 EFLAGS: 00000246 ORIG_RAX: 0000000000000037
> > > > RAX: ffffffffffffffda RBX: 0000000000000005 RCX: 0000000000457569
> > > > RDX: 000000000000006d RSI: 0000000000000084 RDI: 0000000000000003
> > > > RBP: 000000000072bf00 R08: 0000000020000140 R09: 0000000000000000
> > > > R10: 0000000020001100 R11: 0000000000000246 R12: 00007f49918876d4
> > > > R13: 00000000004c7d88 R14: 00000000004ce348 R15: 00000000ffffffff
> > > >
> > > > Uninit was stored to memory at:
> > > > kmsan_save_stack_with_flags mm/kmsan/kmsan.c:246 [inline]
> > > > kmsan_save_stack mm/kmsan/kmsan.c:261 [inline]
> > > > kmsan_internal_chain_origin+0x13d/0x240 mm/kmsan/kmsan.c:469
> > > > kmsan_memcpy_memmove_metadata+0x1a9/0xf70 mm/kmsan/kmsan.c:344
> > > > kmsan_memcpy_metadata+0xb/0x10 mm/kmsan/kmsan.c:362
> > > > __msan_memcpy+0x61/0x70 mm/kmsan/kmsan_instr.c:162
> > > > sctp_copy_laddrs net/sctp/socket.c:5901 [inline]
> > > > sctp_getsockopt_local_addrs net/sctp/socket.c:5967 [inline]
> > > > sctp_getsockopt+0x14f41/0x186f0 net/sctp/socket.c:7477
> > > > sock_common_getsockopt+0x13f/0x180 net/core/sock.c:2937
> > > > __sys_getsockopt+0x489/0x550 net/socket.c:1939
> > > > __do_sys_getsockopt net/socket.c:1950 [inline]
> > > > __se_sys_getsockopt+0xe1/0x100 net/socket.c:1947
> > > > __x64_sys_getsockopt+0x62/0x80 net/socket.c:1947
> > > > do_syscall_64+0xcf/0x110 arch/x86/entry/common.c:291
> > > > entry_SYSCALL_64_after_hwframe+0x63/0xe7
> > > >
> > > > Uninit was stored to memory at:
> > > > kmsan_save_stack_with_flags mm/kmsan/kmsan.c:246 [inline]
> > > > kmsan_save_stack mm/kmsan/kmsan.c:261 [inline]
> > > > kmsan_internal_chain_origin+0x13d/0x240 mm/kmsan/kmsan.c:469
> > > > kmsan_memcpy_memmove_metadata+0x1a9/0xf70 mm/kmsan/kmsan.c:344
> > > > kmsan_memcpy_metadata+0xb/0x10 mm/kmsan/kmsan.c:362
> > > > __msan_memcpy+0x61/0x70 mm/kmsan/kmsan_instr.c:162
> > > > sctp_copy_laddrs net/sctp/socket.c:5890 [inline]
> > > > sctp_getsockopt_local_addrs net/sctp/socket.c:5967 [inline]
> > > > sctp_getsockopt+0x14de8/0x186f0 net/sctp/socket.c:7477
> > > > sock_common_getsockopt+0x13f/0x180 net/core/sock.c:2937
> > > > __sys_getsockopt+0x489/0x550 net/socket.c:1939
> > > > __do_sys_getsockopt net/socket.c:1950 [inline]
> > > > __se_sys_getsockopt+0xe1/0x100 net/socket.c:1947
> > > > __x64_sys_getsockopt+0x62/0x80 net/socket.c:1947
> > > > do_syscall_64+0xcf/0x110 arch/x86/entry/common.c:291
> > > > entry_SYSCALL_64_after_hwframe+0x63/0xe7
> > > >
> > > > Uninit was created at:
> > > > kmsan_save_stack_with_flags mm/kmsan/kmsan.c:246 [inline]
> > > > kmsan_internal_poison_shadow+0x6d/0x130 mm/kmsan/kmsan.c:170
> > > > kmsan_kmalloc+0xa1/0x100 mm/kmsan/kmsan_hooks.c:186
> > > > __kmalloc+0x14c/0x4d0 mm/slub.c:3825
> > > > kmalloc include/linux/slab.h:551 [inline]
> > > > sctp_inet6addr_event+0x60e/0xbd0 net/sctp/ipv6.c:100
> > > > notifier_call_chain kernel/notifier.c:93 [inline]
> > > > __atomic_notifier_call_chain kernel/notifier.c:183 [inline]
> > > > atomic_notifier_call_chain+0x13d/0x240 kernel/notifier.c:193
> > > > inet6addr_notifier_call_chain+0x76/0x90 net/ipv6/addrconf_core.c:107
> > > > ipv6_add_addr+0x2597/0x2890 net/ipv6/addrconf.c:1115
> > > > inet6_addr_add+0xc86/0x1c10 net/ipv6/addrconf.c:2912
> > > > inet6_rtm_newaddr+0x167e/0x3d20 net/ipv6/addrconf.c:4750
> > > > rtnetlink_rcv_msg+0x1148/0x1540 net/core/rtnetlink.c:4947
> > > > netlink_rcv_skb+0x394/0x640 net/netlink/af_netlink.c:2477
> > > > rtnetlink_rcv+0x50/0x60 net/core/rtnetlink.c:4965
> > > > netlink_unicast_kernel net/netlink/af_netlink.c:1310 [inline]
> > > > netlink_unicast+0x1699/0x1740 net/netlink/af_netlink.c:1336
> > > > netlink_sendmsg+0x13c7/0x1440 net/netlink/af_netlink.c:1917
> > > > sock_sendmsg_nosec net/socket.c:621 [inline]
> > > > sock_sendmsg net/socket.c:631 [inline]
> > > > ___sys_sendmsg+0xe3b/0x1240 net/socket.c:2116
> > > > __sys_sendmsg net/socket.c:2154 [inline]
> > > > __do_sys_sendmsg net/socket.c:2163 [inline]
> > > > __se_sys_sendmsg+0x305/0x460 net/socket.c:2161
> > > > __x64_sys_sendmsg+0x4a/0x70 net/socket.c:2161
> > > > do_syscall_64+0xcf/0x110 arch/x86/entry/common.c:291
> > > > entry_SYSCALL_64_after_hwframe+0x63/0xe7
> > > >
> > > > Bytes 32-35 of 2100 are uninitialized
> > > > Memory access of size 2100 starts at ffff888185d8b000
> > > > Data copied to user address 0000000020001108
> > > > ==================================================================
> > > When a network device goes up and sctp_inetaddr_event() is called, it
> > > allocates a partially initialized struct sctp_sockaddr_entry to hold
> > > the newly created address.
> > > The attached reproducer can be then used to read up to 8 uninit bytes
> > > for each of the local addresses.
> > > I guess the devices aren't created so often that this can pose any
> > > security risk, but we probably still need to allocate this structure
> > > with __GFP_ZERO.
> >
> > Agree. Thanks Alexander.
> > Looks like this is the last/only place left with this issue.
Actually there's still a similar bug in IPv4. Memsetting addr->av4 should help:
diff --git a/net/sctp/protocol.c b/net/sctp/protocol.c
index d5878ae55840..f1cbfb4d0c39 100644
--- a/net/sctp/protocol.c
+++ b/net/sctp/protocol.c
@@ -778,6 +778,7 @@ static int sctp_inetaddr_event(struct
notifier_block *this, unsigned long ev,
case NETDEV_UP:
addr = kmalloc(sizeof(struct sctp_sockaddr_entry), GFP_ATOMIC);
if (addr) {
+ memset(&addr->a.v4, 0, sizeof(struct sockaddr_in));
addr->a.v4.sin_family = AF_INET;
addr->a.v4.sin_port = 0;
addr->a.v4.sin_addr.s_addr = ifa->ifa_local;
> This field is not really used by sctp, I will just set it to 0.
>
> diff --git a/net/sctp/ipv6.c b/net/sctp/ipv6.c
> index fc6c5e4bffa5..7f0539db5604 100644
> --- a/net/sctp/ipv6.c
> +++ b/net/sctp/ipv6.c
> @@ -101,6 +101,7 @@ static int sctp_inet6addr_event(struct
> notifier_block *this, unsigned long ev,
> if (addr) {
> addr->a.v6.sin6_family = AF_INET6;
> addr->a.v6.sin6_port = 0;
> + addr->a.v6.sin6_flowinfo = 0;
> addr->a.v6.sin6_addr = ifa->addr;
> addr->a.v6.sin6_scope_id = ifa->idev->dev->ifindex;
> addr->valid = 1;
>
> >
> > > >
> > > > ---
> > > > This bug is generated by a bot. It may contain errors.
> > > > See https://goo.gl/tpsmEJ for more information about syzbot.
> > > > syzbot engineers can be reached at syzkaller@googlegroups.com.
> > > >
> > > > syzbot will keep track of this bug report. See:
> > > > https://goo.gl/tpsmEJ#bug-status-tracking for how to communicate with
> > > > syzbot.
> > > > syzbot can test patches for this bug, for details see:
> > > > https://goo.gl/tpsmEJ#testing-patches
> > > >
> > > > --
> > > > You received this message because you are subscribed to the Google Groups "syzkaller-bugs" group.
> > > > To unsubscribe from this group and stop receiving emails from it, send an email to syzkaller-bugs+unsubscribe@googlegroups.com.
> > > > To view this discussion on the web visit https://groups.google.com/d/msgid/syzkaller-bugs/000000000000311344057c4b6cc3%40google.com.
> > > > For more options, visit https://groups.google.com/d/optout.
> > >
> > >
> > >
> > > --
> > > Alexander Potapenko
> > > Software Engineer
> > >
> > > Google Germany GmbH
> > > Erika-Mann-Straße, 33
> > > 80636 München
> > >
> > > Geschäftsführer: Paul Manicle, Halimah DeLaine Prado
> > > Registergericht und -nummer: Hamburg, HRB 86891
> > > Sitz der Gesellschaft: Hamburg
> >
> > > #ifndef DUMP_BUF_H
> > > #define DUMP_BUF_H
> > >
> > > #ifndef DUMP_MIN_STRLEN
> > > #define DUMP_MIN_STRLEN 1
> > > #endif
> > >
> > > #ifndef DUMP_PARALLEL
> > > #define DUMP_PARALLEL 0
> > > #endif
> > >
> > > #ifndef DUMP_PRINT_BUF_ADDR
> > > #define DUMP_PRINT_BUF_ADDR 0
> > > #endif
> > >
> > > #ifndef DUMP_PRINT_HEX
> > > #define DUMP_PRINT_HEX 0
> > > #endif
> > >
> > > #ifndef DUMP_PRINT_STRING
> > > #define DUMP_PRINT_STRING 0
> > > #endif
> > >
> > > #if DUMP_PARALLEL
> > > pthread_mutex_t out_mutex = PTHREAD_MUTEX_INITIALIZER;
> > > #endif
> > >
> > > void dump_buf(unsigned char *buf, int len) {
> > > int i, nz = 0;
> > > for (i = 0; i < len; i++) {
> > > if (buf[i]) {
> > > nz = 1;
> > > break;
> > > }
> > > }
> > > if (!nz) {
> > > // The buffer is empty.
> > > return;
> > > } else {
> > > #if DUMP_PARALLEL
> > > pthread_mutex_lock(&out_mutex);
> > > #endif
> > > #if DUMP_PRINT_BUF_ADDR
> > > fprintf(stderr, "nonempty buffer at %p\n", buf);
> > > #endif
> > > #if DUMP_PRINT_HEX
> > > for (i=0; i < len; i++) {
> > > if (buf[i]) {
> > > fprintf(stderr, "buf[%d]: %x (%p)\n", i, buf[i], *(void**)&buf[i]);
> > > }
> > > }
> > > #endif // DUMP_PRINT_HEX
> > > #if DUMP_PARALLEL
> > > pthread_mutex_unlock(&out_mutex);
> > > #endif
> > > }
> > > #if DUMP_PARALLEL
> > > pthread_mutex_lock(&out_mutex);
> > > #endif
> > > #if DUMP_PRINT_STRING
> > > for (i = 0; i < len; i++) {
> > > if (buf[i]) {
> > > int str_len = strlen(&buf[i]);
> > > // Short string pieces are too boring.
> > > if (str_len >= DUMP_MIN_STRLEN) {
> > > unsigned char *c;
> > > for (c = &buf[i]; c < &buf[i + str_len]; c++) {
> > > if ((*c > 127) || ((*c < 32) && (*c != 10) && (*c != 13))) {
> > > *c = ' ';
> > > continue;
> > > }
> > > }
> > > // Dump the buffer.
> > > fprintf(stderr, "%s\n", &buf[i]);
> > > }
> > > i += str_len;
> > > }
> > > }
> > > #endif // DUMP_PRINT_STRING
> > > #if DUMP_PARALLEL
> > > pthread_mutex_unlock(&out_mutex);
> > > #endif
> > > }
> > >
> > > #endif
> >
> > > #include <stdio.h>
> > > #include <pthread.h>
> > > #include <sys/types.h> /* See NOTES */
> > > #include <sys/socket.h>
> > > #include <unistd.h>
> > >
> > > #define DUMP_PARALLEL 1
> > > #define DUMP_PRINT_BUF_ADDR 1
> > > #define DUMP_PRINT_STRING 1
> > > #define DUMP_PRINT_HEX 1
> > > #include "dump_buf.h"
> > >
> > > void *setsockopt_fn(void *arg) {
> > > int sock = (int)arg;
> > > struct sockaddr addr;
> > > memset(&addr, 0, sizeof(addr));
> > > addr.sa_family = 2;
> > > addr.sa_data[2] = 0xac;
> > > addr.sa_data[3] = 0x14;
> > > addr.sa_data[4] = 0x14;
> > > setsockopt(sock, 0x84, 0x6e, &addr, 0x10);
> > > }
> > >
> > > #define BUFLEN (0x2c2)
> > > void *getsockopt_fn(void *arg) {
> > > int sock = (int)arg;
> > > char buf[BUFLEN];
> > > memset(buf, 0, BUFLEN);
> > > int socklen = BUFLEN;
> > > getsockopt(sock, 0x84, /*SCTP_GET_LOCAL_ADDRS*/0x6d, buf, &socklen);
> > > dump_buf(&(buf[8]), 32);
> > > }
> > >
> > > void do_work(int sock) {
> > > pthread_t t1, t2;
> > > for (int i = 0; i < 10; i++) {
> > > pthread_create(&t1, NULL, getsockopt_fn, (void*)sock);
> > > pthread_create(&t2, NULL, setsockopt_fn, (void*)sock);
> > > usleep(100);
> > > }
> > > }
> > >
> > > int main(int argc, char *argv[]) {
> > > int res;
> > > int pid = fork();
> > > if (pid == 0) {
> > > int sock = socket(0x2, 0x1, 0x84);
> > > do_work(sock);
> > > }
> > > sleep(10);
> > > return 0;
> > > }
> >
--
Alexander Potapenko
Software Engineer
Google Germany GmbH
Erika-Mann-Straße, 33
80636 München
Geschäftsführer: Paul Manicle, Halimah DeLaine Prado
Registergericht und -nummer: Hamburg, HRB 86891
Sitz der Gesellschaft: Hamburg
^ permalink raw reply related [flat|nested] 9+ messages in thread
* Re: KMSAN: kernel-infoleak in sctp_getsockopt
2019-01-14 9:34 ` Alexander Potapenko
@ 2019-01-14 9:55 ` Xin Long
2019-01-14 9:58 ` Alexander Potapenko
0 siblings, 1 reply; 9+ messages in thread
From: Xin Long @ 2019-01-14 9:55 UTC (permalink / raw)
To: Alexander Potapenko
Cc: Marcelo Ricardo Leitner, syzbot+ad5d327e6936a2e284be, davem,
LKML, linux-sctp, network dev, Neil Horman, syzkaller-bugs,
Vlad Yasevich
On Mon, Jan 14, 2019 at 5:34 PM Alexander Potapenko <glider@google.com> wrote:
>
> On Mon, Dec 10, 2018 at 9:56 AM Xin Long <lucien.xin@gmail.com> wrote:
> >
> > On Thu, Dec 6, 2018 at 8:08 PM Marcelo Ricardo Leitner
> > <marcelo.leitner@gmail.com> wrote:
> > >
> > > On Thu, Dec 06, 2018 at 11:36:08AM +0100, Alexander Potapenko wrote:
> > > > On Wed, Dec 5, 2018 at 8:31 PM syzbot
> > > > <syzbot+ad5d327e6936a2e284be@syzkaller.appspotmail.com> wrote:
> > > > >
> > > > > Hello,
> > > > >
> > > > > syzbot found the following crash on:
> > > > >
> > > > > HEAD commit: fffec98ae2a6 net: proper support for CONFIG_GENERIC_CSUM o..
> > > > > git tree: https://github.com/google/kmsan.git/master
> > > > > console output: https://syzkaller.appspot.com/x/log.txt?x=12e84a47400000
> > > > > kernel config: https://syzkaller.appspot.com/x/.config?x=56b48b46dafe4516
> > > > > dashboard link: https://syzkaller.appspot.com/bug?extid=ad5d327e6936a2e284be
> > > > > compiler: clang version 8.0.0 (trunk 343298)
> > > > > syz repro: https://syzkaller.appspot.com/x/repro.syz?x=103cd225400000
> > > > >
> > > > > IMPORTANT: if you fix the bug, please add the following tag to the commit:
> > > > > Reported-by: syzbot+ad5d327e6936a2e284be@syzkaller.appspotmail.com
> > > > >
> > > > > 8021q: adding VLAN 0 to HW filter on device team0
> > > > > 8021q: adding VLAN 0 to HW filter on device team0
> > > > > 8021q: adding VLAN 0 to HW filter on device team0
> > > > > 8021q: adding VLAN 0 to HW filter on device team0
> > > > > ==================================================================
> > > > > BUG: KMSAN: kernel-infoleak in _copy_to_user+0x19a/0x230 lib/usercopy.c:33
> > > > > CPU: 1 PID: 8164 Comm: syz-executor2 Not tainted 4.20.0-rc3+ #95
> > > > > Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS
> > > > > Google 01/01/2011
> > > > > Call Trace:
> > > > > __dump_stack lib/dump_stack.c:77 [inline]
> > > > > dump_stack+0x32d/0x480 lib/dump_stack.c:113
> > > > > kmsan_report+0x12c/0x290 mm/kmsan/kmsan.c:683
> > > > > kmsan_internal_check_memory+0x32a/0xa50 mm/kmsan/kmsan.c:743
> > > > > kmsan_copy_to_user+0x78/0xd0 mm/kmsan/kmsan_hooks.c:634
> > > > > _copy_to_user+0x19a/0x230 lib/usercopy.c:33
> > > > > copy_to_user include/linux/uaccess.h:183 [inline]
> > > > > sctp_getsockopt_local_addrs net/sctp/socket.c:5998 [inline]
> > > > > sctp_getsockopt+0x15248/0x186f0 net/sctp/socket.c:7477
> > > > > sock_common_getsockopt+0x13f/0x180 net/core/sock.c:2937
> > > > > __sys_getsockopt+0x489/0x550 net/socket.c:1939
> > > > > __do_sys_getsockopt net/socket.c:1950 [inline]
> > > > > __se_sys_getsockopt+0xe1/0x100 net/socket.c:1947
> > > > > __x64_sys_getsockopt+0x62/0x80 net/socket.c:1947
> > > > > do_syscall_64+0xcf/0x110 arch/x86/entry/common.c:291
> > > > > entry_SYSCALL_64_after_hwframe+0x63/0xe7
> > > > > RIP: 0033:0x457569
> > > > > Code: fd b3 fb ff c3 66 2e 0f 1f 84 00 00 00 00 00 66 90 48 89 f8 48 89 f7
> > > > > 48 89 d6 48 89 ca 4d 89 c2 4d 89 c8 4c 8b 4c 24 08 0f 05 <48> 3d 01 f0 ff
> > > > > ff 0f 83 cb b3 fb ff c3 66 2e 0f 1f 84 00 00 00 00
> > > > > RSP: 002b:00007f4991886c78 EFLAGS: 00000246 ORIG_RAX: 0000000000000037
> > > > > RAX: ffffffffffffffda RBX: 0000000000000005 RCX: 0000000000457569
> > > > > RDX: 000000000000006d RSI: 0000000000000084 RDI: 0000000000000003
> > > > > RBP: 000000000072bf00 R08: 0000000020000140 R09: 0000000000000000
> > > > > R10: 0000000020001100 R11: 0000000000000246 R12: 00007f49918876d4
> > > > > R13: 00000000004c7d88 R14: 00000000004ce348 R15: 00000000ffffffff
> > > > >
> > > > > Uninit was stored to memory at:
> > > > > kmsan_save_stack_with_flags mm/kmsan/kmsan.c:246 [inline]
> > > > > kmsan_save_stack mm/kmsan/kmsan.c:261 [inline]
> > > > > kmsan_internal_chain_origin+0x13d/0x240 mm/kmsan/kmsan.c:469
> > > > > kmsan_memcpy_memmove_metadata+0x1a9/0xf70 mm/kmsan/kmsan.c:344
> > > > > kmsan_memcpy_metadata+0xb/0x10 mm/kmsan/kmsan.c:362
> > > > > __msan_memcpy+0x61/0x70 mm/kmsan/kmsan_instr.c:162
> > > > > sctp_copy_laddrs net/sctp/socket.c:5901 [inline]
> > > > > sctp_getsockopt_local_addrs net/sctp/socket.c:5967 [inline]
> > > > > sctp_getsockopt+0x14f41/0x186f0 net/sctp/socket.c:7477
> > > > > sock_common_getsockopt+0x13f/0x180 net/core/sock.c:2937
> > > > > __sys_getsockopt+0x489/0x550 net/socket.c:1939
> > > > > __do_sys_getsockopt net/socket.c:1950 [inline]
> > > > > __se_sys_getsockopt+0xe1/0x100 net/socket.c:1947
> > > > > __x64_sys_getsockopt+0x62/0x80 net/socket.c:1947
> > > > > do_syscall_64+0xcf/0x110 arch/x86/entry/common.c:291
> > > > > entry_SYSCALL_64_after_hwframe+0x63/0xe7
> > > > >
> > > > > Uninit was stored to memory at:
> > > > > kmsan_save_stack_with_flags mm/kmsan/kmsan.c:246 [inline]
> > > > > kmsan_save_stack mm/kmsan/kmsan.c:261 [inline]
> > > > > kmsan_internal_chain_origin+0x13d/0x240 mm/kmsan/kmsan.c:469
> > > > > kmsan_memcpy_memmove_metadata+0x1a9/0xf70 mm/kmsan/kmsan.c:344
> > > > > kmsan_memcpy_metadata+0xb/0x10 mm/kmsan/kmsan.c:362
> > > > > __msan_memcpy+0x61/0x70 mm/kmsan/kmsan_instr.c:162
> > > > > sctp_copy_laddrs net/sctp/socket.c:5890 [inline]
> > > > > sctp_getsockopt_local_addrs net/sctp/socket.c:5967 [inline]
> > > > > sctp_getsockopt+0x14de8/0x186f0 net/sctp/socket.c:7477
> > > > > sock_common_getsockopt+0x13f/0x180 net/core/sock.c:2937
> > > > > __sys_getsockopt+0x489/0x550 net/socket.c:1939
> > > > > __do_sys_getsockopt net/socket.c:1950 [inline]
> > > > > __se_sys_getsockopt+0xe1/0x100 net/socket.c:1947
> > > > > __x64_sys_getsockopt+0x62/0x80 net/socket.c:1947
> > > > > do_syscall_64+0xcf/0x110 arch/x86/entry/common.c:291
> > > > > entry_SYSCALL_64_after_hwframe+0x63/0xe7
> > > > >
> > > > > Uninit was created at:
> > > > > kmsan_save_stack_with_flags mm/kmsan/kmsan.c:246 [inline]
> > > > > kmsan_internal_poison_shadow+0x6d/0x130 mm/kmsan/kmsan.c:170
> > > > > kmsan_kmalloc+0xa1/0x100 mm/kmsan/kmsan_hooks.c:186
> > > > > __kmalloc+0x14c/0x4d0 mm/slub.c:3825
> > > > > kmalloc include/linux/slab.h:551 [inline]
> > > > > sctp_inet6addr_event+0x60e/0xbd0 net/sctp/ipv6.c:100
> > > > > notifier_call_chain kernel/notifier.c:93 [inline]
> > > > > __atomic_notifier_call_chain kernel/notifier.c:183 [inline]
> > > > > atomic_notifier_call_chain+0x13d/0x240 kernel/notifier.c:193
> > > > > inet6addr_notifier_call_chain+0x76/0x90 net/ipv6/addrconf_core.c:107
> > > > > ipv6_add_addr+0x2597/0x2890 net/ipv6/addrconf.c:1115
> > > > > inet6_addr_add+0xc86/0x1c10 net/ipv6/addrconf.c:2912
> > > > > inet6_rtm_newaddr+0x167e/0x3d20 net/ipv6/addrconf.c:4750
> > > > > rtnetlink_rcv_msg+0x1148/0x1540 net/core/rtnetlink.c:4947
> > > > > netlink_rcv_skb+0x394/0x640 net/netlink/af_netlink.c:2477
> > > > > rtnetlink_rcv+0x50/0x60 net/core/rtnetlink.c:4965
> > > > > netlink_unicast_kernel net/netlink/af_netlink.c:1310 [inline]
> > > > > netlink_unicast+0x1699/0x1740 net/netlink/af_netlink.c:1336
> > > > > netlink_sendmsg+0x13c7/0x1440 net/netlink/af_netlink.c:1917
> > > > > sock_sendmsg_nosec net/socket.c:621 [inline]
> > > > > sock_sendmsg net/socket.c:631 [inline]
> > > > > ___sys_sendmsg+0xe3b/0x1240 net/socket.c:2116
> > > > > __sys_sendmsg net/socket.c:2154 [inline]
> > > > > __do_sys_sendmsg net/socket.c:2163 [inline]
> > > > > __se_sys_sendmsg+0x305/0x460 net/socket.c:2161
> > > > > __x64_sys_sendmsg+0x4a/0x70 net/socket.c:2161
> > > > > do_syscall_64+0xcf/0x110 arch/x86/entry/common.c:291
> > > > > entry_SYSCALL_64_after_hwframe+0x63/0xe7
> > > > >
> > > > > Bytes 32-35 of 2100 are uninitialized
> > > > > Memory access of size 2100 starts at ffff888185d8b000
> > > > > Data copied to user address 0000000020001108
> > > > > ==================================================================
> > > > When a network device goes up and sctp_inetaddr_event() is called, it
> > > > allocates a partially initialized struct sctp_sockaddr_entry to hold
> > > > the newly created address.
> > > > The attached reproducer can be then used to read up to 8 uninit bytes
> > > > for each of the local addresses.
> > > > I guess the devices aren't created so often that this can pose any
> > > > security risk, but we probably still need to allocate this structure
> > > > with __GFP_ZERO.
> > >
> > > Agree. Thanks Alexander.
> > > Looks like this is the last/only place left with this issue.
> Actually there's still a similar bug in IPv4. Memsetting addr->av4 should help:
seems right, because of __pad of struct sockaddr_in.
Do you have any reproducer for this?
We should use kzalloc for all sctp_sockaddr_entry allocations.
Thanks.
>
> diff --git a/net/sctp/protocol.c b/net/sctp/protocol.c
> index d5878ae55840..f1cbfb4d0c39 100644
> --- a/net/sctp/protocol.c
> +++ b/net/sctp/protocol.c
> @@ -778,6 +778,7 @@ static int sctp_inetaddr_event(struct
> notifier_block *this, unsigned long ev,
> case NETDEV_UP:
> addr = kmalloc(sizeof(struct sctp_sockaddr_entry), GFP_ATOMIC);
> if (addr) {
> + memset(&addr->a.v4, 0, sizeof(struct sockaddr_in));
> addr->a.v4.sin_family = AF_INET;
> addr->a.v4.sin_port = 0;
> addr->a.v4.sin_addr.s_addr = ifa->ifa_local;
>
>
> > This field is not really used by sctp, I will just set it to 0.
> >
> > diff --git a/net/sctp/ipv6.c b/net/sctp/ipv6.c
> > index fc6c5e4bffa5..7f0539db5604 100644
> > --- a/net/sctp/ipv6.c
> > +++ b/net/sctp/ipv6.c
> > @@ -101,6 +101,7 @@ static int sctp_inet6addr_event(struct
> > notifier_block *this, unsigned long ev,
> > if (addr) {
> > addr->a.v6.sin6_family = AF_INET6;
> > addr->a.v6.sin6_port = 0;
> > + addr->a.v6.sin6_flowinfo = 0;
> > addr->a.v6.sin6_addr = ifa->addr;
> > addr->a.v6.sin6_scope_id = ifa->idev->dev->ifindex;
> > addr->valid = 1;
> >
> > >
> > > > >
> > > > > ---
> > > > > This bug is generated by a bot. It may contain errors.
> > > > > See https://goo.gl/tpsmEJ for more information about syzbot.
> > > > > syzbot engineers can be reached at syzkaller@googlegroups.com.
> > > > >
> > > > > syzbot will keep track of this bug report. See:
> > > > > https://goo.gl/tpsmEJ#bug-status-tracking for how to communicate with
> > > > > syzbot.
> > > > > syzbot can test patches for this bug, for details see:
> > > > > https://goo.gl/tpsmEJ#testing-patches
> > > > >
> > > > > --
> > > > > You received this message because you are subscribed to the Google Groups "syzkaller-bugs" group.
> > > > > To unsubscribe from this group and stop receiving emails from it, send an email to syzkaller-bugs+unsubscribe@googlegroups.com.
> > > > > To view this discussion on the web visit https://groups.google.com/d/msgid/syzkaller-bugs/000000000000311344057c4b6cc3%40google.com.
> > > > > For more options, visit https://groups.google.com/d/optout.
> > > >
> > > >
> > > >
> > > > --
> > > > Alexander Potapenko
> > > > Software Engineer
> > > >
> > > > Google Germany GmbH
> > > > Erika-Mann-Straße, 33
> > > > 80636 München
> > > >
> > > > Geschäftsführer: Paul Manicle, Halimah DeLaine Prado
> > > > Registergericht und -nummer: Hamburg, HRB 86891
> > > > Sitz der Gesellschaft: Hamburg
> > >
> > > > #ifndef DUMP_BUF_H
> > > > #define DUMP_BUF_H
> > > >
> > > > #ifndef DUMP_MIN_STRLEN
> > > > #define DUMP_MIN_STRLEN 1
> > > > #endif
> > > >
> > > > #ifndef DUMP_PARALLEL
> > > > #define DUMP_PARALLEL 0
> > > > #endif
> > > >
> > > > #ifndef DUMP_PRINT_BUF_ADDR
> > > > #define DUMP_PRINT_BUF_ADDR 0
> > > > #endif
> > > >
> > > > #ifndef DUMP_PRINT_HEX
> > > > #define DUMP_PRINT_HEX 0
> > > > #endif
> > > >
> > > > #ifndef DUMP_PRINT_STRING
> > > > #define DUMP_PRINT_STRING 0
> > > > #endif
> > > >
> > > > #if DUMP_PARALLEL
> > > > pthread_mutex_t out_mutex = PTHREAD_MUTEX_INITIALIZER;
> > > > #endif
> > > >
> > > > void dump_buf(unsigned char *buf, int len) {
> > > > int i, nz = 0;
> > > > for (i = 0; i < len; i++) {
> > > > if (buf[i]) {
> > > > nz = 1;
> > > > break;
> > > > }
> > > > }
> > > > if (!nz) {
> > > > // The buffer is empty.
> > > > return;
> > > > } else {
> > > > #if DUMP_PARALLEL
> > > > pthread_mutex_lock(&out_mutex);
> > > > #endif
> > > > #if DUMP_PRINT_BUF_ADDR
> > > > fprintf(stderr, "nonempty buffer at %p\n", buf);
> > > > #endif
> > > > #if DUMP_PRINT_HEX
> > > > for (i=0; i < len; i++) {
> > > > if (buf[i]) {
> > > > fprintf(stderr, "buf[%d]: %x (%p)\n", i, buf[i], *(void**)&buf[i]);
> > > > }
> > > > }
> > > > #endif // DUMP_PRINT_HEX
> > > > #if DUMP_PARALLEL
> > > > pthread_mutex_unlock(&out_mutex);
> > > > #endif
> > > > }
> > > > #if DUMP_PARALLEL
> > > > pthread_mutex_lock(&out_mutex);
> > > > #endif
> > > > #if DUMP_PRINT_STRING
> > > > for (i = 0; i < len; i++) {
> > > > if (buf[i]) {
> > > > int str_len = strlen(&buf[i]);
> > > > // Short string pieces are too boring.
> > > > if (str_len >= DUMP_MIN_STRLEN) {
> > > > unsigned char *c;
> > > > for (c = &buf[i]; c < &buf[i + str_len]; c++) {
> > > > if ((*c > 127) || ((*c < 32) && (*c != 10) && (*c != 13))) {
> > > > *c = ' ';
> > > > continue;
> > > > }
> > > > }
> > > > // Dump the buffer.
> > > > fprintf(stderr, "%s\n", &buf[i]);
> > > > }
> > > > i += str_len;
> > > > }
> > > > }
> > > > #endif // DUMP_PRINT_STRING
> > > > #if DUMP_PARALLEL
> > > > pthread_mutex_unlock(&out_mutex);
> > > > #endif
> > > > }
> > > >
> > > > #endif
> > >
> > > > #include <stdio.h>
> > > > #include <pthread.h>
> > > > #include <sys/types.h> /* See NOTES */
> > > > #include <sys/socket.h>
> > > > #include <unistd.h>
> > > >
> > > > #define DUMP_PARALLEL 1
> > > > #define DUMP_PRINT_BUF_ADDR 1
> > > > #define DUMP_PRINT_STRING 1
> > > > #define DUMP_PRINT_HEX 1
> > > > #include "dump_buf.h"
> > > >
> > > > void *setsockopt_fn(void *arg) {
> > > > int sock = (int)arg;
> > > > struct sockaddr addr;
> > > > memset(&addr, 0, sizeof(addr));
> > > > addr.sa_family = 2;
> > > > addr.sa_data[2] = 0xac;
> > > > addr.sa_data[3] = 0x14;
> > > > addr.sa_data[4] = 0x14;
> > > > setsockopt(sock, 0x84, 0x6e, &addr, 0x10);
> > > > }
> > > >
> > > > #define BUFLEN (0x2c2)
> > > > void *getsockopt_fn(void *arg) {
> > > > int sock = (int)arg;
> > > > char buf[BUFLEN];
> > > > memset(buf, 0, BUFLEN);
> > > > int socklen = BUFLEN;
> > > > getsockopt(sock, 0x84, /*SCTP_GET_LOCAL_ADDRS*/0x6d, buf, &socklen);
> > > > dump_buf(&(buf[8]), 32);
> > > > }
> > > >
> > > > void do_work(int sock) {
> > > > pthread_t t1, t2;
> > > > for (int i = 0; i < 10; i++) {
> > > > pthread_create(&t1, NULL, getsockopt_fn, (void*)sock);
> > > > pthread_create(&t2, NULL, setsockopt_fn, (void*)sock);
> > > > usleep(100);
> > > > }
> > > > }
> > > >
> > > > int main(int argc, char *argv[]) {
> > > > int res;
> > > > int pid = fork();
> > > > if (pid == 0) {
> > > > int sock = socket(0x2, 0x1, 0x84);
> > > > do_work(sock);
> > > > }
> > > > sleep(10);
> > > > return 0;
> > > > }
> > >
>
>
>
> --
> Alexander Potapenko
> Software Engineer
>
> Google Germany GmbH
> Erika-Mann-Straße, 33
> 80636 München
>
> Geschäftsführer: Paul Manicle, Halimah DeLaine Prado
> Registergericht und -nummer: Hamburg, HRB 86891
> Sitz der Gesellschaft: Hamburg
^ permalink raw reply [flat|nested] 9+ messages in thread
* Re: KMSAN: kernel-infoleak in sctp_getsockopt
2019-01-14 9:55 ` Xin Long
@ 2019-01-14 9:58 ` Alexander Potapenko
2019-01-14 11:09 ` Dmitry Vyukov
0 siblings, 1 reply; 9+ messages in thread
From: Alexander Potapenko @ 2019-01-14 9:58 UTC (permalink / raw)
To: Xin Long
Cc: Marcelo Ricardo Leitner, syzbot+ad5d327e6936a2e284be, davem,
LKML, linux-sctp, network dev, Neil Horman, syzkaller-bugs,
Vlad Yasevich
On Mon, Jan 14, 2019 at 10:56 AM Xin Long <lucien.xin@gmail.com> wrote:
>
> On Mon, Jan 14, 2019 at 5:34 PM Alexander Potapenko <glider@google.com> wrote:
> >
> > On Mon, Dec 10, 2018 at 9:56 AM Xin Long <lucien.xin@gmail.com> wrote:
> > >
> > > On Thu, Dec 6, 2018 at 8:08 PM Marcelo Ricardo Leitner
> > > <marcelo.leitner@gmail.com> wrote:
> > > >
> > > > On Thu, Dec 06, 2018 at 11:36:08AM +0100, Alexander Potapenko wrote:
> > > > > On Wed, Dec 5, 2018 at 8:31 PM syzbot
> > > > > <syzbot+ad5d327e6936a2e284be@syzkaller.appspotmail.com> wrote:
> > > > > >
> > > > > > Hello,
> > > > > >
> > > > > > syzbot found the following crash on:
> > > > > >
> > > > > > HEAD commit: fffec98ae2a6 net: proper support for CONFIG_GENERIC_CSUM o..
> > > > > > git tree: https://github.com/google/kmsan.git/master
> > > > > > console output: https://syzkaller.appspot.com/x/log.txt?x=12e84a47400000
> > > > > > kernel config: https://syzkaller.appspot.com/x/.config?x=56b48b46dafe4516
> > > > > > dashboard link: https://syzkaller.appspot.com/bug?extid=ad5d327e6936a2e284be
> > > > > > compiler: clang version 8.0.0 (trunk 343298)
> > > > > > syz repro: https://syzkaller.appspot.com/x/repro.syz?x=103cd225400000
> > > > > >
> > > > > > IMPORTANT: if you fix the bug, please add the following tag to the commit:
> > > > > > Reported-by: syzbot+ad5d327e6936a2e284be@syzkaller.appspotmail.com
> > > > > >
> > > > > > 8021q: adding VLAN 0 to HW filter on device team0
> > > > > > 8021q: adding VLAN 0 to HW filter on device team0
> > > > > > 8021q: adding VLAN 0 to HW filter on device team0
> > > > > > 8021q: adding VLAN 0 to HW filter on device team0
> > > > > > ==================================================================
> > > > > > BUG: KMSAN: kernel-infoleak in _copy_to_user+0x19a/0x230 lib/usercopy.c:33
> > > > > > CPU: 1 PID: 8164 Comm: syz-executor2 Not tainted 4.20.0-rc3+ #95
> > > > > > Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS
> > > > > > Google 01/01/2011
> > > > > > Call Trace:
> > > > > > __dump_stack lib/dump_stack.c:77 [inline]
> > > > > > dump_stack+0x32d/0x480 lib/dump_stack.c:113
> > > > > > kmsan_report+0x12c/0x290 mm/kmsan/kmsan.c:683
> > > > > > kmsan_internal_check_memory+0x32a/0xa50 mm/kmsan/kmsan.c:743
> > > > > > kmsan_copy_to_user+0x78/0xd0 mm/kmsan/kmsan_hooks.c:634
> > > > > > _copy_to_user+0x19a/0x230 lib/usercopy.c:33
> > > > > > copy_to_user include/linux/uaccess.h:183 [inline]
> > > > > > sctp_getsockopt_local_addrs net/sctp/socket.c:5998 [inline]
> > > > > > sctp_getsockopt+0x15248/0x186f0 net/sctp/socket.c:7477
> > > > > > sock_common_getsockopt+0x13f/0x180 net/core/sock.c:2937
> > > > > > __sys_getsockopt+0x489/0x550 net/socket.c:1939
> > > > > > __do_sys_getsockopt net/socket.c:1950 [inline]
> > > > > > __se_sys_getsockopt+0xe1/0x100 net/socket.c:1947
> > > > > > __x64_sys_getsockopt+0x62/0x80 net/socket.c:1947
> > > > > > do_syscall_64+0xcf/0x110 arch/x86/entry/common.c:291
> > > > > > entry_SYSCALL_64_after_hwframe+0x63/0xe7
> > > > > > RIP: 0033:0x457569
> > > > > > Code: fd b3 fb ff c3 66 2e 0f 1f 84 00 00 00 00 00 66 90 48 89 f8 48 89 f7
> > > > > > 48 89 d6 48 89 ca 4d 89 c2 4d 89 c8 4c 8b 4c 24 08 0f 05 <48> 3d 01 f0 ff
> > > > > > ff 0f 83 cb b3 fb ff c3 66 2e 0f 1f 84 00 00 00 00
> > > > > > RSP: 002b:00007f4991886c78 EFLAGS: 00000246 ORIG_RAX: 0000000000000037
> > > > > > RAX: ffffffffffffffda RBX: 0000000000000005 RCX: 0000000000457569
> > > > > > RDX: 000000000000006d RSI: 0000000000000084 RDI: 0000000000000003
> > > > > > RBP: 000000000072bf00 R08: 0000000020000140 R09: 0000000000000000
> > > > > > R10: 0000000020001100 R11: 0000000000000246 R12: 00007f49918876d4
> > > > > > R13: 00000000004c7d88 R14: 00000000004ce348 R15: 00000000ffffffff
> > > > > >
> > > > > > Uninit was stored to memory at:
> > > > > > kmsan_save_stack_with_flags mm/kmsan/kmsan.c:246 [inline]
> > > > > > kmsan_save_stack mm/kmsan/kmsan.c:261 [inline]
> > > > > > kmsan_internal_chain_origin+0x13d/0x240 mm/kmsan/kmsan.c:469
> > > > > > kmsan_memcpy_memmove_metadata+0x1a9/0xf70 mm/kmsan/kmsan.c:344
> > > > > > kmsan_memcpy_metadata+0xb/0x10 mm/kmsan/kmsan.c:362
> > > > > > __msan_memcpy+0x61/0x70 mm/kmsan/kmsan_instr.c:162
> > > > > > sctp_copy_laddrs net/sctp/socket.c:5901 [inline]
> > > > > > sctp_getsockopt_local_addrs net/sctp/socket.c:5967 [inline]
> > > > > > sctp_getsockopt+0x14f41/0x186f0 net/sctp/socket.c:7477
> > > > > > sock_common_getsockopt+0x13f/0x180 net/core/sock.c:2937
> > > > > > __sys_getsockopt+0x489/0x550 net/socket.c:1939
> > > > > > __do_sys_getsockopt net/socket.c:1950 [inline]
> > > > > > __se_sys_getsockopt+0xe1/0x100 net/socket.c:1947
> > > > > > __x64_sys_getsockopt+0x62/0x80 net/socket.c:1947
> > > > > > do_syscall_64+0xcf/0x110 arch/x86/entry/common.c:291
> > > > > > entry_SYSCALL_64_after_hwframe+0x63/0xe7
> > > > > >
> > > > > > Uninit was stored to memory at:
> > > > > > kmsan_save_stack_with_flags mm/kmsan/kmsan.c:246 [inline]
> > > > > > kmsan_save_stack mm/kmsan/kmsan.c:261 [inline]
> > > > > > kmsan_internal_chain_origin+0x13d/0x240 mm/kmsan/kmsan.c:469
> > > > > > kmsan_memcpy_memmove_metadata+0x1a9/0xf70 mm/kmsan/kmsan.c:344
> > > > > > kmsan_memcpy_metadata+0xb/0x10 mm/kmsan/kmsan.c:362
> > > > > > __msan_memcpy+0x61/0x70 mm/kmsan/kmsan_instr.c:162
> > > > > > sctp_copy_laddrs net/sctp/socket.c:5890 [inline]
> > > > > > sctp_getsockopt_local_addrs net/sctp/socket.c:5967 [inline]
> > > > > > sctp_getsockopt+0x14de8/0x186f0 net/sctp/socket.c:7477
> > > > > > sock_common_getsockopt+0x13f/0x180 net/core/sock.c:2937
> > > > > > __sys_getsockopt+0x489/0x550 net/socket.c:1939
> > > > > > __do_sys_getsockopt net/socket.c:1950 [inline]
> > > > > > __se_sys_getsockopt+0xe1/0x100 net/socket.c:1947
> > > > > > __x64_sys_getsockopt+0x62/0x80 net/socket.c:1947
> > > > > > do_syscall_64+0xcf/0x110 arch/x86/entry/common.c:291
> > > > > > entry_SYSCALL_64_after_hwframe+0x63/0xe7
> > > > > >
> > > > > > Uninit was created at:
> > > > > > kmsan_save_stack_with_flags mm/kmsan/kmsan.c:246 [inline]
> > > > > > kmsan_internal_poison_shadow+0x6d/0x130 mm/kmsan/kmsan.c:170
> > > > > > kmsan_kmalloc+0xa1/0x100 mm/kmsan/kmsan_hooks.c:186
> > > > > > __kmalloc+0x14c/0x4d0 mm/slub.c:3825
> > > > > > kmalloc include/linux/slab.h:551 [inline]
> > > > > > sctp_inet6addr_event+0x60e/0xbd0 net/sctp/ipv6.c:100
> > > > > > notifier_call_chain kernel/notifier.c:93 [inline]
> > > > > > __atomic_notifier_call_chain kernel/notifier.c:183 [inline]
> > > > > > atomic_notifier_call_chain+0x13d/0x240 kernel/notifier.c:193
> > > > > > inet6addr_notifier_call_chain+0x76/0x90 net/ipv6/addrconf_core.c:107
> > > > > > ipv6_add_addr+0x2597/0x2890 net/ipv6/addrconf.c:1115
> > > > > > inet6_addr_add+0xc86/0x1c10 net/ipv6/addrconf.c:2912
> > > > > > inet6_rtm_newaddr+0x167e/0x3d20 net/ipv6/addrconf.c:4750
> > > > > > rtnetlink_rcv_msg+0x1148/0x1540 net/core/rtnetlink.c:4947
> > > > > > netlink_rcv_skb+0x394/0x640 net/netlink/af_netlink.c:2477
> > > > > > rtnetlink_rcv+0x50/0x60 net/core/rtnetlink.c:4965
> > > > > > netlink_unicast_kernel net/netlink/af_netlink.c:1310 [inline]
> > > > > > netlink_unicast+0x1699/0x1740 net/netlink/af_netlink.c:1336
> > > > > > netlink_sendmsg+0x13c7/0x1440 net/netlink/af_netlink.c:1917
> > > > > > sock_sendmsg_nosec net/socket.c:621 [inline]
> > > > > > sock_sendmsg net/socket.c:631 [inline]
> > > > > > ___sys_sendmsg+0xe3b/0x1240 net/socket.c:2116
> > > > > > __sys_sendmsg net/socket.c:2154 [inline]
> > > > > > __do_sys_sendmsg net/socket.c:2163 [inline]
> > > > > > __se_sys_sendmsg+0x305/0x460 net/socket.c:2161
> > > > > > __x64_sys_sendmsg+0x4a/0x70 net/socket.c:2161
> > > > > > do_syscall_64+0xcf/0x110 arch/x86/entry/common.c:291
> > > > > > entry_SYSCALL_64_after_hwframe+0x63/0xe7
> > > > > >
> > > > > > Bytes 32-35 of 2100 are uninitialized
> > > > > > Memory access of size 2100 starts at ffff888185d8b000
> > > > > > Data copied to user address 0000000020001108
> > > > > > ==================================================================
> > > > > When a network device goes up and sctp_inetaddr_event() is called, it
> > > > > allocates a partially initialized struct sctp_sockaddr_entry to hold
> > > > > the newly created address.
> > > > > The attached reproducer can be then used to read up to 8 uninit bytes
> > > > > for each of the local addresses.
> > > > > I guess the devices aren't created so often that this can pose any
> > > > > security risk, but we probably still need to allocate this structure
> > > > > with __GFP_ZERO.
> > > >
> > > > Agree. Thanks Alexander.
> > > > Looks like this is the last/only place left with this issue.
> > Actually there's still a similar bug in IPv4. Memsetting addr->av4 should help:
> seems right, because of __pad of struct sockaddr_in.
> Do you have any reproducer for this?
I just took the above reproducer. Not sure what changed (perhaps the
configuration of my VM), but now the uninitialized data is allocated
by sctp_inetaddr_event()
> We should use kzalloc for all sctp_sockaddr_entry allocations.
>
> Thanks.
>
> >
> > diff --git a/net/sctp/protocol.c b/net/sctp/protocol.c
> > index d5878ae55840..f1cbfb4d0c39 100644
> > --- a/net/sctp/protocol.c
> > +++ b/net/sctp/protocol.c
> > @@ -778,6 +778,7 @@ static int sctp_inetaddr_event(struct
> > notifier_block *this, unsigned long ev,
> > case NETDEV_UP:
> > addr = kmalloc(sizeof(struct sctp_sockaddr_entry), GFP_ATOMIC);
> > if (addr) {
> > + memset(&addr->a.v4, 0, sizeof(struct sockaddr_in));
> > addr->a.v4.sin_family = AF_INET;
> > addr->a.v4.sin_port = 0;
> > addr->a.v4.sin_addr.s_addr = ifa->ifa_local;
> >
> >
> > > This field is not really used by sctp, I will just set it to 0.
> > >
> > > diff --git a/net/sctp/ipv6.c b/net/sctp/ipv6.c
> > > index fc6c5e4bffa5..7f0539db5604 100644
> > > --- a/net/sctp/ipv6.c
> > > +++ b/net/sctp/ipv6.c
> > > @@ -101,6 +101,7 @@ static int sctp_inet6addr_event(struct
> > > notifier_block *this, unsigned long ev,
> > > if (addr) {
> > > addr->a.v6.sin6_family = AF_INET6;
> > > addr->a.v6.sin6_port = 0;
> > > + addr->a.v6.sin6_flowinfo = 0;
> > > addr->a.v6.sin6_addr = ifa->addr;
> > > addr->a.v6.sin6_scope_id = ifa->idev->dev->ifindex;
> > > addr->valid = 1;
> > >
> > > >
> > > > > >
> > > > > > ---
> > > > > > This bug is generated by a bot. It may contain errors.
> > > > > > See https://goo.gl/tpsmEJ for more information about syzbot.
> > > > > > syzbot engineers can be reached at syzkaller@googlegroups.com.
> > > > > >
> > > > > > syzbot will keep track of this bug report. See:
> > > > > > https://goo.gl/tpsmEJ#bug-status-tracking for how to communicate with
> > > > > > syzbot.
> > > > > > syzbot can test patches for this bug, for details see:
> > > > > > https://goo.gl/tpsmEJ#testing-patches
> > > > > >
> > > > > > --
> > > > > > You received this message because you are subscribed to the Google Groups "syzkaller-bugs" group.
> > > > > > To unsubscribe from this group and stop receiving emails from it, send an email to syzkaller-bugs+unsubscribe@googlegroups.com.
> > > > > > To view this discussion on the web visit https://groups.google.com/d/msgid/syzkaller-bugs/000000000000311344057c4b6cc3%40google.com.
> > > > > > For more options, visit https://groups.google.com/d/optout.
> > > > >
> > > > >
> > > > >
> > > > > --
> > > > > Alexander Potapenko
> > > > > Software Engineer
> > > > >
> > > > > Google Germany GmbH
> > > > > Erika-Mann-Straße, 33
> > > > > 80636 München
> > > > >
> > > > > Geschäftsführer: Paul Manicle, Halimah DeLaine Prado
> > > > > Registergericht und -nummer: Hamburg, HRB 86891
> > > > > Sitz der Gesellschaft: Hamburg
> > > >
> > > > > #ifndef DUMP_BUF_H
> > > > > #define DUMP_BUF_H
> > > > >
> > > > > #ifndef DUMP_MIN_STRLEN
> > > > > #define DUMP_MIN_STRLEN 1
> > > > > #endif
> > > > >
> > > > > #ifndef DUMP_PARALLEL
> > > > > #define DUMP_PARALLEL 0
> > > > > #endif
> > > > >
> > > > > #ifndef DUMP_PRINT_BUF_ADDR
> > > > > #define DUMP_PRINT_BUF_ADDR 0
> > > > > #endif
> > > > >
> > > > > #ifndef DUMP_PRINT_HEX
> > > > > #define DUMP_PRINT_HEX 0
> > > > > #endif
> > > > >
> > > > > #ifndef DUMP_PRINT_STRING
> > > > > #define DUMP_PRINT_STRING 0
> > > > > #endif
> > > > >
> > > > > #if DUMP_PARALLEL
> > > > > pthread_mutex_t out_mutex = PTHREAD_MUTEX_INITIALIZER;
> > > > > #endif
> > > > >
> > > > > void dump_buf(unsigned char *buf, int len) {
> > > > > int i, nz = 0;
> > > > > for (i = 0; i < len; i++) {
> > > > > if (buf[i]) {
> > > > > nz = 1;
> > > > > break;
> > > > > }
> > > > > }
> > > > > if (!nz) {
> > > > > // The buffer is empty.
> > > > > return;
> > > > > } else {
> > > > > #if DUMP_PARALLEL
> > > > > pthread_mutex_lock(&out_mutex);
> > > > > #endif
> > > > > #if DUMP_PRINT_BUF_ADDR
> > > > > fprintf(stderr, "nonempty buffer at %p\n", buf);
> > > > > #endif
> > > > > #if DUMP_PRINT_HEX
> > > > > for (i=0; i < len; i++) {
> > > > > if (buf[i]) {
> > > > > fprintf(stderr, "buf[%d]: %x (%p)\n", i, buf[i], *(void**)&buf[i]);
> > > > > }
> > > > > }
> > > > > #endif // DUMP_PRINT_HEX
> > > > > #if DUMP_PARALLEL
> > > > > pthread_mutex_unlock(&out_mutex);
> > > > > #endif
> > > > > }
> > > > > #if DUMP_PARALLEL
> > > > > pthread_mutex_lock(&out_mutex);
> > > > > #endif
> > > > > #if DUMP_PRINT_STRING
> > > > > for (i = 0; i < len; i++) {
> > > > > if (buf[i]) {
> > > > > int str_len = strlen(&buf[i]);
> > > > > // Short string pieces are too boring.
> > > > > if (str_len >= DUMP_MIN_STRLEN) {
> > > > > unsigned char *c;
> > > > > for (c = &buf[i]; c < &buf[i + str_len]; c++) {
> > > > > if ((*c > 127) || ((*c < 32) && (*c != 10) && (*c != 13))) {
> > > > > *c = ' ';
> > > > > continue;
> > > > > }
> > > > > }
> > > > > // Dump the buffer.
> > > > > fprintf(stderr, "%s\n", &buf[i]);
> > > > > }
> > > > > i += str_len;
> > > > > }
> > > > > }
> > > > > #endif // DUMP_PRINT_STRING
> > > > > #if DUMP_PARALLEL
> > > > > pthread_mutex_unlock(&out_mutex);
> > > > > #endif
> > > > > }
> > > > >
> > > > > #endif
> > > >
> > > > > #include <stdio.h>
> > > > > #include <pthread.h>
> > > > > #include <sys/types.h> /* See NOTES */
> > > > > #include <sys/socket.h>
> > > > > #include <unistd.h>
> > > > >
> > > > > #define DUMP_PARALLEL 1
> > > > > #define DUMP_PRINT_BUF_ADDR 1
> > > > > #define DUMP_PRINT_STRING 1
> > > > > #define DUMP_PRINT_HEX 1
> > > > > #include "dump_buf.h"
> > > > >
> > > > > void *setsockopt_fn(void *arg) {
> > > > > int sock = (int)arg;
> > > > > struct sockaddr addr;
> > > > > memset(&addr, 0, sizeof(addr));
> > > > > addr.sa_family = 2;
> > > > > addr.sa_data[2] = 0xac;
> > > > > addr.sa_data[3] = 0x14;
> > > > > addr.sa_data[4] = 0x14;
> > > > > setsockopt(sock, 0x84, 0x6e, &addr, 0x10);
> > > > > }
> > > > >
> > > > > #define BUFLEN (0x2c2)
> > > > > void *getsockopt_fn(void *arg) {
> > > > > int sock = (int)arg;
> > > > > char buf[BUFLEN];
> > > > > memset(buf, 0, BUFLEN);
> > > > > int socklen = BUFLEN;
> > > > > getsockopt(sock, 0x84, /*SCTP_GET_LOCAL_ADDRS*/0x6d, buf, &socklen);
> > > > > dump_buf(&(buf[8]), 32);
> > > > > }
> > > > >
> > > > > void do_work(int sock) {
> > > > > pthread_t t1, t2;
> > > > > for (int i = 0; i < 10; i++) {
> > > > > pthread_create(&t1, NULL, getsockopt_fn, (void*)sock);
> > > > > pthread_create(&t2, NULL, setsockopt_fn, (void*)sock);
> > > > > usleep(100);
> > > > > }
> > > > > }
> > > > >
> > > > > int main(int argc, char *argv[]) {
> > > > > int res;
> > > > > int pid = fork();
> > > > > if (pid == 0) {
> > > > > int sock = socket(0x2, 0x1, 0x84);
> > > > > do_work(sock);
> > > > > }
> > > > > sleep(10);
> > > > > return 0;
> > > > > }
> > > >
> >
> >
> >
> > --
> > Alexander Potapenko
> > Software Engineer
> >
> > Google Germany GmbH
> > Erika-Mann-Straße, 33
> > 80636 München
> >
> > Geschäftsführer: Paul Manicle, Halimah DeLaine Prado
> > Registergericht und -nummer: Hamburg, HRB 86891
> > Sitz der Gesellschaft: Hamburg
--
Alexander Potapenko
Software Engineer
Google Germany GmbH
Erika-Mann-Straße, 33
80636 München
Geschäftsführer: Paul Manicle, Halimah DeLaine Prado
Registergericht und -nummer: Hamburg, HRB 86891
Sitz der Gesellschaft: Hamburg
^ permalink raw reply [flat|nested] 9+ messages in thread
* Re: KMSAN: kernel-infoleak in sctp_getsockopt
2019-01-14 9:58 ` Alexander Potapenko
@ 2019-01-14 11:09 ` Dmitry Vyukov
0 siblings, 0 replies; 9+ messages in thread
From: Dmitry Vyukov @ 2019-01-14 11:09 UTC (permalink / raw)
To: Alexander Potapenko
Cc: Xin Long, Marcelo Ricardo Leitner, syzbot+ad5d327e6936a2e284be,
davem, LKML, linux-sctp, network dev, Neil Horman,
syzkaller-bugs, Vlad Yasevich
On Mon, Jan 14, 2019 at 10:58 AM 'Alexander Potapenko' via
syzkaller-bugs <syzkaller-bugs@googlegroups.com> wrote:
>
> On Mon, Jan 14, 2019 at 10:56 AM Xin Long <lucien.xin@gmail.com> wrote:
> >
> > On Mon, Jan 14, 2019 at 5:34 PM Alexander Potapenko <glider@google.com> wrote:
> > >
> > > On Mon, Dec 10, 2018 at 9:56 AM Xin Long <lucien.xin@gmail.com> wrote:
> > > >
> > > > On Thu, Dec 6, 2018 at 8:08 PM Marcelo Ricardo Leitner
> > > > <marcelo.leitner@gmail.com> wrote:
> > > > >
> > > > > On Thu, Dec 06, 2018 at 11:36:08AM +0100, Alexander Potapenko wrote:
> > > > > > On Wed, Dec 5, 2018 at 8:31 PM syzbot
> > > > > > <syzbot+ad5d327e6936a2e284be@syzkaller.appspotmail.com> wrote:
> > > > > > >
> > > > > > > Hello,
> > > > > > >
> > > > > > > syzbot found the following crash on:
> > > > > > >
> > > > > > > HEAD commit: fffec98ae2a6 net: proper support for CONFIG_GENERIC_CSUM o..
> > > > > > > git tree: https://github.com/google/kmsan.git/master
> > > > > > > console output: https://syzkaller.appspot.com/x/log.txt?x=12e84a47400000
> > > > > > > kernel config: https://syzkaller.appspot.com/x/.config?x=56b48b46dafe4516
> > > > > > > dashboard link: https://syzkaller.appspot.com/bug?extid=ad5d327e6936a2e284be
> > > > > > > compiler: clang version 8.0.0 (trunk 343298)
> > > > > > > syz repro: https://syzkaller.appspot.com/x/repro.syz?x=103cd225400000
> > > > > > >
> > > > > > > IMPORTANT: if you fix the bug, please add the following tag to the commit:
> > > > > > > Reported-by: syzbot+ad5d327e6936a2e284be@syzkaller.appspotmail.com
> > > > > > >
> > > > > > > 8021q: adding VLAN 0 to HW filter on device team0
> > > > > > > 8021q: adding VLAN 0 to HW filter on device team0
> > > > > > > 8021q: adding VLAN 0 to HW filter on device team0
> > > > > > > 8021q: adding VLAN 0 to HW filter on device team0
> > > > > > > ==================================================================
> > > > > > > BUG: KMSAN: kernel-infoleak in _copy_to_user+0x19a/0x230 lib/usercopy.c:33
> > > > > > > CPU: 1 PID: 8164 Comm: syz-executor2 Not tainted 4.20.0-rc3+ #95
> > > > > > > Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS
> > > > > > > Google 01/01/2011
> > > > > > > Call Trace:
> > > > > > > __dump_stack lib/dump_stack.c:77 [inline]
> > > > > > > dump_stack+0x32d/0x480 lib/dump_stack.c:113
> > > > > > > kmsan_report+0x12c/0x290 mm/kmsan/kmsan.c:683
> > > > > > > kmsan_internal_check_memory+0x32a/0xa50 mm/kmsan/kmsan.c:743
> > > > > > > kmsan_copy_to_user+0x78/0xd0 mm/kmsan/kmsan_hooks.c:634
> > > > > > > _copy_to_user+0x19a/0x230 lib/usercopy.c:33
> > > > > > > copy_to_user include/linux/uaccess.h:183 [inline]
> > > > > > > sctp_getsockopt_local_addrs net/sctp/socket.c:5998 [inline]
> > > > > > > sctp_getsockopt+0x15248/0x186f0 net/sctp/socket.c:7477
> > > > > > > sock_common_getsockopt+0x13f/0x180 net/core/sock.c:2937
> > > > > > > __sys_getsockopt+0x489/0x550 net/socket.c:1939
> > > > > > > __do_sys_getsockopt net/socket.c:1950 [inline]
> > > > > > > __se_sys_getsockopt+0xe1/0x100 net/socket.c:1947
> > > > > > > __x64_sys_getsockopt+0x62/0x80 net/socket.c:1947
> > > > > > > do_syscall_64+0xcf/0x110 arch/x86/entry/common.c:291
> > > > > > > entry_SYSCALL_64_after_hwframe+0x63/0xe7
> > > > > > > RIP: 0033:0x457569
> > > > > > > Code: fd b3 fb ff c3 66 2e 0f 1f 84 00 00 00 00 00 66 90 48 89 f8 48 89 f7
> > > > > > > 48 89 d6 48 89 ca 4d 89 c2 4d 89 c8 4c 8b 4c 24 08 0f 05 <48> 3d 01 f0 ff
> > > > > > > ff 0f 83 cb b3 fb ff c3 66 2e 0f 1f 84 00 00 00 00
> > > > > > > RSP: 002b:00007f4991886c78 EFLAGS: 00000246 ORIG_RAX: 0000000000000037
> > > > > > > RAX: ffffffffffffffda RBX: 0000000000000005 RCX: 0000000000457569
> > > > > > > RDX: 000000000000006d RSI: 0000000000000084 RDI: 0000000000000003
> > > > > > > RBP: 000000000072bf00 R08: 0000000020000140 R09: 0000000000000000
> > > > > > > R10: 0000000020001100 R11: 0000000000000246 R12: 00007f49918876d4
> > > > > > > R13: 00000000004c7d88 R14: 00000000004ce348 R15: 00000000ffffffff
> > > > > > >
> > > > > > > Uninit was stored to memory at:
> > > > > > > kmsan_save_stack_with_flags mm/kmsan/kmsan.c:246 [inline]
> > > > > > > kmsan_save_stack mm/kmsan/kmsan.c:261 [inline]
> > > > > > > kmsan_internal_chain_origin+0x13d/0x240 mm/kmsan/kmsan.c:469
> > > > > > > kmsan_memcpy_memmove_metadata+0x1a9/0xf70 mm/kmsan/kmsan.c:344
> > > > > > > kmsan_memcpy_metadata+0xb/0x10 mm/kmsan/kmsan.c:362
> > > > > > > __msan_memcpy+0x61/0x70 mm/kmsan/kmsan_instr.c:162
> > > > > > > sctp_copy_laddrs net/sctp/socket.c:5901 [inline]
> > > > > > > sctp_getsockopt_local_addrs net/sctp/socket.c:5967 [inline]
> > > > > > > sctp_getsockopt+0x14f41/0x186f0 net/sctp/socket.c:7477
> > > > > > > sock_common_getsockopt+0x13f/0x180 net/core/sock.c:2937
> > > > > > > __sys_getsockopt+0x489/0x550 net/socket.c:1939
> > > > > > > __do_sys_getsockopt net/socket.c:1950 [inline]
> > > > > > > __se_sys_getsockopt+0xe1/0x100 net/socket.c:1947
> > > > > > > __x64_sys_getsockopt+0x62/0x80 net/socket.c:1947
> > > > > > > do_syscall_64+0xcf/0x110 arch/x86/entry/common.c:291
> > > > > > > entry_SYSCALL_64_after_hwframe+0x63/0xe7
> > > > > > >
> > > > > > > Uninit was stored to memory at:
> > > > > > > kmsan_save_stack_with_flags mm/kmsan/kmsan.c:246 [inline]
> > > > > > > kmsan_save_stack mm/kmsan/kmsan.c:261 [inline]
> > > > > > > kmsan_internal_chain_origin+0x13d/0x240 mm/kmsan/kmsan.c:469
> > > > > > > kmsan_memcpy_memmove_metadata+0x1a9/0xf70 mm/kmsan/kmsan.c:344
> > > > > > > kmsan_memcpy_metadata+0xb/0x10 mm/kmsan/kmsan.c:362
> > > > > > > __msan_memcpy+0x61/0x70 mm/kmsan/kmsan_instr.c:162
> > > > > > > sctp_copy_laddrs net/sctp/socket.c:5890 [inline]
> > > > > > > sctp_getsockopt_local_addrs net/sctp/socket.c:5967 [inline]
> > > > > > > sctp_getsockopt+0x14de8/0x186f0 net/sctp/socket.c:7477
> > > > > > > sock_common_getsockopt+0x13f/0x180 net/core/sock.c:2937
> > > > > > > __sys_getsockopt+0x489/0x550 net/socket.c:1939
> > > > > > > __do_sys_getsockopt net/socket.c:1950 [inline]
> > > > > > > __se_sys_getsockopt+0xe1/0x100 net/socket.c:1947
> > > > > > > __x64_sys_getsockopt+0x62/0x80 net/socket.c:1947
> > > > > > > do_syscall_64+0xcf/0x110 arch/x86/entry/common.c:291
> > > > > > > entry_SYSCALL_64_after_hwframe+0x63/0xe7
> > > > > > >
> > > > > > > Uninit was created at:
> > > > > > > kmsan_save_stack_with_flags mm/kmsan/kmsan.c:246 [inline]
> > > > > > > kmsan_internal_poison_shadow+0x6d/0x130 mm/kmsan/kmsan.c:170
> > > > > > > kmsan_kmalloc+0xa1/0x100 mm/kmsan/kmsan_hooks.c:186
> > > > > > > __kmalloc+0x14c/0x4d0 mm/slub.c:3825
> > > > > > > kmalloc include/linux/slab.h:551 [inline]
> > > > > > > sctp_inet6addr_event+0x60e/0xbd0 net/sctp/ipv6.c:100
> > > > > > > notifier_call_chain kernel/notifier.c:93 [inline]
> > > > > > > __atomic_notifier_call_chain kernel/notifier.c:183 [inline]
> > > > > > > atomic_notifier_call_chain+0x13d/0x240 kernel/notifier.c:193
> > > > > > > inet6addr_notifier_call_chain+0x76/0x90 net/ipv6/addrconf_core.c:107
> > > > > > > ipv6_add_addr+0x2597/0x2890 net/ipv6/addrconf.c:1115
> > > > > > > inet6_addr_add+0xc86/0x1c10 net/ipv6/addrconf.c:2912
> > > > > > > inet6_rtm_newaddr+0x167e/0x3d20 net/ipv6/addrconf.c:4750
> > > > > > > rtnetlink_rcv_msg+0x1148/0x1540 net/core/rtnetlink.c:4947
> > > > > > > netlink_rcv_skb+0x394/0x640 net/netlink/af_netlink.c:2477
> > > > > > > rtnetlink_rcv+0x50/0x60 net/core/rtnetlink.c:4965
> > > > > > > netlink_unicast_kernel net/netlink/af_netlink.c:1310 [inline]
> > > > > > > netlink_unicast+0x1699/0x1740 net/netlink/af_netlink.c:1336
> > > > > > > netlink_sendmsg+0x13c7/0x1440 net/netlink/af_netlink.c:1917
> > > > > > > sock_sendmsg_nosec net/socket.c:621 [inline]
> > > > > > > sock_sendmsg net/socket.c:631 [inline]
> > > > > > > ___sys_sendmsg+0xe3b/0x1240 net/socket.c:2116
> > > > > > > __sys_sendmsg net/socket.c:2154 [inline]
> > > > > > > __do_sys_sendmsg net/socket.c:2163 [inline]
> > > > > > > __se_sys_sendmsg+0x305/0x460 net/socket.c:2161
> > > > > > > __x64_sys_sendmsg+0x4a/0x70 net/socket.c:2161
> > > > > > > do_syscall_64+0xcf/0x110 arch/x86/entry/common.c:291
> > > > > > > entry_SYSCALL_64_after_hwframe+0x63/0xe7
> > > > > > >
> > > > > > > Bytes 32-35 of 2100 are uninitialized
> > > > > > > Memory access of size 2100 starts at ffff888185d8b000
> > > > > > > Data copied to user address 0000000020001108
> > > > > > > ==================================================================
> > > > > > When a network device goes up and sctp_inetaddr_event() is called, it
> > > > > > allocates a partially initialized struct sctp_sockaddr_entry to hold
> > > > > > the newly created address.
> > > > > > The attached reproducer can be then used to read up to 8 uninit bytes
> > > > > > for each of the local addresses.
> > > > > > I guess the devices aren't created so often that this can pose any
> > > > > > security risk, but we probably still need to allocate this structure
> > > > > > with __GFP_ZERO.
> > > > >
> > > > > Agree. Thanks Alexander.
> > > > > Looks like this is the last/only place left with this issue.
> > > Actually there's still a similar bug in IPv4. Memsetting addr->av4 should help:
> > seems right, because of __pad of struct sockaddr_in.
> > Do you have any reproducer for this?
> I just took the above reproducer. Not sure what changed (perhaps the
> configuration of my VM), but now the uninitialized data is allocated
> by sctp_inetaddr_event()
> > We should use kzalloc for all sctp_sockaddr_entry allocations.
The second version was just reported as:
KMSAN: kernel-infoleak in sctp_getsockopt (2)
https://groups.google.com/forum/#!topic/syzkaller-bugs/eOTX3BR1O4s
> >
> > Thanks.
> >
> > >
> > > diff --git a/net/sctp/protocol.c b/net/sctp/protocol.c
> > > index d5878ae55840..f1cbfb4d0c39 100644
> > > --- a/net/sctp/protocol.c
> > > +++ b/net/sctp/protocol.c
> > > @@ -778,6 +778,7 @@ static int sctp_inetaddr_event(struct
> > > notifier_block *this, unsigned long ev,
> > > case NETDEV_UP:
> > > addr = kmalloc(sizeof(struct sctp_sockaddr_entry), GFP_ATOMIC);
> > > if (addr) {
> > > + memset(&addr->a.v4, 0, sizeof(struct sockaddr_in));
> > > addr->a.v4.sin_family = AF_INET;
> > > addr->a.v4.sin_port = 0;
> > > addr->a.v4.sin_addr.s_addr = ifa->ifa_local;
> > >
> > >
> > > > This field is not really used by sctp, I will just set it to 0.
> > > >
> > > > diff --git a/net/sctp/ipv6.c b/net/sctp/ipv6.c
> > > > index fc6c5e4bffa5..7f0539db5604 100644
> > > > --- a/net/sctp/ipv6.c
> > > > +++ b/net/sctp/ipv6.c
> > > > @@ -101,6 +101,7 @@ static int sctp_inet6addr_event(struct
> > > > notifier_block *this, unsigned long ev,
> > > > if (addr) {
> > > > addr->a.v6.sin6_family = AF_INET6;
> > > > addr->a.v6.sin6_port = 0;
> > > > + addr->a.v6.sin6_flowinfo = 0;
> > > > addr->a.v6.sin6_addr = ifa->addr;
> > > > addr->a.v6.sin6_scope_id = ifa->idev->dev->ifindex;
> > > > addr->valid = 1;
> > > >
> > > > >
> > > > > > >
> > > > > > > ---
> > > > > > > This bug is generated by a bot. It may contain errors.
> > > > > > > See https://goo.gl/tpsmEJ for more information about syzbot.
> > > > > > > syzbot engineers can be reached at syzkaller@googlegroups.com.
> > > > > > >
> > > > > > > syzbot will keep track of this bug report. See:
> > > > > > > https://goo.gl/tpsmEJ#bug-status-tracking for how to communicate with
> > > > > > > syzbot.
> > > > > > > syzbot can test patches for this bug, for details see:
> > > > > > > https://goo.gl/tpsmEJ#testing-patches
> > > > > > >
> > > > > > > --
> > > > > > > You received this message because you are subscribed to the Google Groups "syzkaller-bugs" group.
> > > > > > > To unsubscribe from this group and stop receiving emails from it, send an email to syzkaller-bugs+unsubscribe@googlegroups.com.
> > > > > > > To view this discussion on the web visit https://groups.google.com/d/msgid/syzkaller-bugs/000000000000311344057c4b6cc3%40google.com.
> > > > > > > For more options, visit https://groups.google.com/d/optout.
> > > > > >
> > > > > >
> > > > > >
> > > > > > --
> > > > > > Alexander Potapenko
> > > > > > Software Engineer
> > > > > >
> > > > > > Google Germany GmbH
> > > > > > Erika-Mann-Straße, 33
> > > > > > 80636 München
> > > > > >
> > > > > > Geschäftsführer: Paul Manicle, Halimah DeLaine Prado
> > > > > > Registergericht und -nummer: Hamburg, HRB 86891
> > > > > > Sitz der Gesellschaft: Hamburg
> > > > >
> > > > > > #ifndef DUMP_BUF_H
> > > > > > #define DUMP_BUF_H
> > > > > >
> > > > > > #ifndef DUMP_MIN_STRLEN
> > > > > > #define DUMP_MIN_STRLEN 1
> > > > > > #endif
> > > > > >
> > > > > > #ifndef DUMP_PARALLEL
> > > > > > #define DUMP_PARALLEL 0
> > > > > > #endif
> > > > > >
> > > > > > #ifndef DUMP_PRINT_BUF_ADDR
> > > > > > #define DUMP_PRINT_BUF_ADDR 0
> > > > > > #endif
> > > > > >
> > > > > > #ifndef DUMP_PRINT_HEX
> > > > > > #define DUMP_PRINT_HEX 0
> > > > > > #endif
> > > > > >
> > > > > > #ifndef DUMP_PRINT_STRING
> > > > > > #define DUMP_PRINT_STRING 0
> > > > > > #endif
> > > > > >
> > > > > > #if DUMP_PARALLEL
> > > > > > pthread_mutex_t out_mutex = PTHREAD_MUTEX_INITIALIZER;
> > > > > > #endif
> > > > > >
> > > > > > void dump_buf(unsigned char *buf, int len) {
> > > > > > int i, nz = 0;
> > > > > > for (i = 0; i < len; i++) {
> > > > > > if (buf[i]) {
> > > > > > nz = 1;
> > > > > > break;
> > > > > > }
> > > > > > }
> > > > > > if (!nz) {
> > > > > > // The buffer is empty.
> > > > > > return;
> > > > > > } else {
> > > > > > #if DUMP_PARALLEL
> > > > > > pthread_mutex_lock(&out_mutex);
> > > > > > #endif
> > > > > > #if DUMP_PRINT_BUF_ADDR
> > > > > > fprintf(stderr, "nonempty buffer at %p\n", buf);
> > > > > > #endif
> > > > > > #if DUMP_PRINT_HEX
> > > > > > for (i=0; i < len; i++) {
> > > > > > if (buf[i]) {
> > > > > > fprintf(stderr, "buf[%d]: %x (%p)\n", i, buf[i], *(void**)&buf[i]);
> > > > > > }
> > > > > > }
> > > > > > #endif // DUMP_PRINT_HEX
> > > > > > #if DUMP_PARALLEL
> > > > > > pthread_mutex_unlock(&out_mutex);
> > > > > > #endif
> > > > > > }
> > > > > > #if DUMP_PARALLEL
> > > > > > pthread_mutex_lock(&out_mutex);
> > > > > > #endif
> > > > > > #if DUMP_PRINT_STRING
> > > > > > for (i = 0; i < len; i++) {
> > > > > > if (buf[i]) {
> > > > > > int str_len = strlen(&buf[i]);
> > > > > > // Short string pieces are too boring.
> > > > > > if (str_len >= DUMP_MIN_STRLEN) {
> > > > > > unsigned char *c;
> > > > > > for (c = &buf[i]; c < &buf[i + str_len]; c++) {
> > > > > > if ((*c > 127) || ((*c < 32) && (*c != 10) && (*c != 13))) {
> > > > > > *c = ' ';
> > > > > > continue;
> > > > > > }
> > > > > > }
> > > > > > // Dump the buffer.
> > > > > > fprintf(stderr, "%s\n", &buf[i]);
> > > > > > }
> > > > > > i += str_len;
> > > > > > }
> > > > > > }
> > > > > > #endif // DUMP_PRINT_STRING
> > > > > > #if DUMP_PARALLEL
> > > > > > pthread_mutex_unlock(&out_mutex);
> > > > > > #endif
> > > > > > }
> > > > > >
> > > > > > #endif
> > > > >
> > > > > > #include <stdio.h>
> > > > > > #include <pthread.h>
> > > > > > #include <sys/types.h> /* See NOTES */
> > > > > > #include <sys/socket.h>
> > > > > > #include <unistd.h>
> > > > > >
> > > > > > #define DUMP_PARALLEL 1
> > > > > > #define DUMP_PRINT_BUF_ADDR 1
> > > > > > #define DUMP_PRINT_STRING 1
> > > > > > #define DUMP_PRINT_HEX 1
> > > > > > #include "dump_buf.h"
> > > > > >
> > > > > > void *setsockopt_fn(void *arg) {
> > > > > > int sock = (int)arg;
> > > > > > struct sockaddr addr;
> > > > > > memset(&addr, 0, sizeof(addr));
> > > > > > addr.sa_family = 2;
> > > > > > addr.sa_data[2] = 0xac;
> > > > > > addr.sa_data[3] = 0x14;
> > > > > > addr.sa_data[4] = 0x14;
> > > > > > setsockopt(sock, 0x84, 0x6e, &addr, 0x10);
> > > > > > }
> > > > > >
> > > > > > #define BUFLEN (0x2c2)
> > > > > > void *getsockopt_fn(void *arg) {
> > > > > > int sock = (int)arg;
> > > > > > char buf[BUFLEN];
> > > > > > memset(buf, 0, BUFLEN);
> > > > > > int socklen = BUFLEN;
> > > > > > getsockopt(sock, 0x84, /*SCTP_GET_LOCAL_ADDRS*/0x6d, buf, &socklen);
> > > > > > dump_buf(&(buf[8]), 32);
> > > > > > }
> > > > > >
> > > > > > void do_work(int sock) {
> > > > > > pthread_t t1, t2;
> > > > > > for (int i = 0; i < 10; i++) {
> > > > > > pthread_create(&t1, NULL, getsockopt_fn, (void*)sock);
> > > > > > pthread_create(&t2, NULL, setsockopt_fn, (void*)sock);
> > > > > > usleep(100);
> > > > > > }
> > > > > > }
> > > > > >
> > > > > > int main(int argc, char *argv[]) {
> > > > > > int res;
> > > > > > int pid = fork();
> > > > > > if (pid == 0) {
> > > > > > int sock = socket(0x2, 0x1, 0x84);
> > > > > > do_work(sock);
> > > > > > }
> > > > > > sleep(10);
> > > > > > return 0;
> > > > > > }
^ permalink raw reply [flat|nested] 9+ messages in thread
end of thread, other threads:[~2019-01-14 11:09 UTC | newest]
Thread overview: 9+ messages (download: mbox.gz / follow: Atom feed)
-- links below jump to the message on this page --
2018-12-05 19:31 KMSAN: kernel-infoleak in sctp_getsockopt syzbot
2018-12-06 10:36 ` Alexander Potapenko
2018-12-06 11:06 ` Marcelo Ricardo Leitner
2018-12-06 11:35 ` Alexander Potapenko
2018-12-10 8:56 ` Xin Long
2019-01-14 9:34 ` Alexander Potapenko
2019-01-14 9:55 ` Xin Long
2019-01-14 9:58 ` Alexander Potapenko
2019-01-14 11:09 ` Dmitry Vyukov
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