llc: only change llc->dev when bind() succeeds
commit
2d327a79ee176930dc72c131a970c891d367c1dc upstream.
My latest patch, attempting to fix the refcount leak in a minimal
way turned out to add a new bug.
Whenever the bind operation fails before we attempt to grab
a reference count on a device, we might release the device refcount
of a prior successful bind() operation.
syzbot was not happy about this [1].
Note to stable teams:
Make sure commit
b37a46683739 ("netdevice: add the case if dev is NULL")
is already present in your trees.
[1]
general protection fault, probably for non-canonical address 0xdffffc0000000070: 0000 [#1] PREEMPT SMP KASAN
KASAN: null-ptr-deref in range [0x0000000000000380-0x0000000000000387]
CPU: 1 PID: 3590 Comm: syz-executor361 Tainted: G W 5.17.0-syzkaller-04796-g169e77764adc #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
RIP: 0010:llc_ui_connect+0x400/0xcb0 net/llc/af_llc.c:500
Code: 80 3c 02 00 0f 85 fc 07 00 00 4c 8b a5 38 05 00 00 48 b8 00 00 00 00 00 fc ff df 49 8d bc 24 80 03 00 00 48 89 fa 48 c1 ea 03 <80> 3c 02 00 0f 85 a9 07 00 00 49 8b b4 24 80 03 00 00 4c 89 f2 48
RSP: 0018:
ffffc900038cfcc0 EFLAGS:
00010202
RAX:
dffffc0000000000 RBX:
ffff8880756eb600 RCX:
0000000000000000
RDX:
0000000000000070 RSI:
ffffc900038cfe3e RDI:
0000000000000380
RBP:
ffff888015ee5000 R08:
0000000000000001 R09:
ffff888015ee5535
R10:
ffffed1002bdcaa6 R11:
0000000000000000 R12:
0000000000000000
R13:
ffffc900038cfe37 R14:
ffffc900038cfe38 R15:
ffff888015ee5012
FS:
0000555555acd300(0000) GS:
ffff8880b9d00000(0000) knlGS:
0000000000000000
CS: 0010 DS: 0000 ES: 0000 CR0:
0000000080050033
CR2:
0000000020000280 CR3:
0000000077db6000 CR4:
00000000003506e0
DR0:
0000000000000000 DR1:
0000000000000000 DR2:
0000000000000000
DR3:
0000000000000000 DR6:
00000000fffe0ff0 DR7:
0000000000000400
Call Trace:
<TASK>
__sys_connect_file+0x155/0x1a0 net/socket.c:1900
__sys_connect+0x161/0x190 net/socket.c:1917
__do_sys_connect net/socket.c:1927 [inline]
__se_sys_connect net/socket.c:1924 [inline]
__x64_sys_connect+0x6f/0xb0 net/socket.c:1924
do_syscall_x64 arch/x86/entry/common.c:50 [inline]
do_syscall_64+0x35/0xb0 arch/x86/entry/common.c:80
entry_SYSCALL_64_after_hwframe+0x44/0xae
RIP: 0033:0x7f016acb90b9
Code: 28 c3 e8 2a 14 00 00 66 2e 0f 1f 84 00 00 00 00 00 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 73 01 c3 48 c7 c1 c0 ff ff ff f7 d8 64 89 01 48
RSP: 002b:
00007ffd417947f8 EFLAGS:
00000246 ORIG_RAX:
000000000000002a
RAX:
ffffffffffffffda RBX:
0000000000000000 RCX:
00007f016acb90b9
RDX:
0000000000000010 RSI:
0000000020000140 RDI:
0000000000000003
RBP:
00007f016ac7d0a0 R08:
0000000000000000 R09:
0000000000000000
R10:
0000000000000000 R11:
0000000000000246 R12:
00007f016ac7d130
R13:
0000000000000000 R14:
0000000000000000 R15:
0000000000000000
</TASK>
Modules linked in:
---[ end trace
0000000000000000 ]---
RIP: 0010:llc_ui_connect+0x400/0xcb0 net/llc/af_llc.c:500
Fixes:
764f4eb6846f ("llc: fix netdevice reference leaks in llc_ui_bind()")
Signed-off-by: Eric Dumazet <edumazet@google.com>
Reported-by: syzbot <syzkaller@googlegroups.com>
Cc: 赵子轩 <beraphin@gmail.com>
Cc: Stoyan Manolov <smanolov@suse.de>
Link: https://lore.kernel.org/r/20220325035827.360418-1-eric.dumazet@gmail.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>