Re: BUG: corrupted list in p9_write_work

[syzbot <syzbot+1788bd5d4e051da6ec08@syzkaller.appspotmail.com>]

syzbot has found a reproducer for the following crash on:

HEAD commit:    050cdc6c9501 Merge git://git.kernel.org/pub/scm/linux/kern..
git tree:       upstream
console output: https://syzkaller.appspot.com/x/log.txt?x=1386bce1400000
kernel config:  https://syzkaller.appspot.com/x/.config?x=49927b422dcf0b29
dashboard link: https://syzkaller.appspot.com/bug?extid=1788bd5d4e051da6ec08
compiler:       gcc (GCC) 8.0.1 20180413 (experimental)
syz repro:      https://syzkaller.appspot.com/x/repro.syz?x=1196b7ba400000
C reproducer:   https://syzkaller.appspot.com/x/repro.c?x=1022391e400000

IMPORTANT: if you fix the bug, please add the following tag to the commit:
Reported-by: syzbot+1788bd5d4e051da6ec08@syzkaller.appspotmail.com

8021q: adding VLAN 0 to HW filter on device team0
8021q: adding VLAN 0 to HW filter on device team0
list_add corruption. prev->next should be next (ffff8801c5b17ab0), but was  
ffff8801c5b17ac0. (prev=ffff8801a92d1b58).
------------[ cut here ]------------
kernel BUG at lib/list_debug.c:28!
invalid opcode: 0000 [#1] SMP KASAN
CPU: 0 PID: 13 Comm: kworker/0:1 Not tainted 4.19.0-rc1+ #212
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS  
Google 01/01/2011
FS-Cache: Duplicate cookie detected
Workqueue: events p9_write_work
FS-Cache: O-cookie c=000000008e4eb276 [p=000000002fd7b0b4 fl=222 nc=0 na=1]
RIP: 0010:__list_add_valid.cold.0+0x23/0x25 lib/list_debug.c:26
Code: e8 4f 2b 5a fe eb 97 48 89 d9 48 c7 c7 60 b2 3a 87 e8 62 05 02 fe 0f  
0b 48 89 f1 48 c7 c7 20 b3 3a 87 48 89 de e8 4e 05 02 fe <0f> 0b 4c 89 e2  
48 89 de 48 c7 c7 60 b4 3a 87 e8 3a 05 02 fe 0f 0b
RSP: 0018:ffff8801d9f17590 EFLAGS: 00010282
FS-Cache: O-cookie d=0000000068a887e4 n=00000000257e8f2f
RAX: 0000000000000075 RBX: ffff8801c5b17ab0 RCX: 0000000000000000
RDX: 0000000000000000 RSI: ffffffff8163ac01 RDI: 0000000000000001
RBP: ffff8801d9f175a8 R08: ffff8801d9f06340 R09: ffffed003b605010
FS-Cache: O-key=[10] '
R10: ffffed003b605010 R11: ffff8801db028087 R12: ffff8801a92d1b58
R13: ffff8801a92d1b58 R14: ffff8801c5b17b04 R15: ffff8801a92d1b58
FS:  0000000000000000(0000) GS:ffff8801db000000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
34
CR2: 00000000006dc138 CR3: 00000001c845c000 CR4: 00000000001406f0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
32
Call Trace:
  __list_add include/linux/list.h:60 [inline]
  list_add_tail include/linux/list.h:93 [inline]
  list_move_tail include/linux/list.h:183 [inline]
  p9_write_work+0x34e/0xd50 net/9p/trans_fd.c:470
39
34
37
  process_one_work+0xc73/0x1aa0 kernel/workqueue.c:2153
38
31
36
31
39
'
FS-Cache: N-cookie c=00000000da38e585 [p=000000002fd7b0b4 fl=2 nc=0 na=1]
FS-Cache: N-cookie d=0000000068a887e4 n=000000005afa2e39
FS-Cache: N-key=[10] '
34
32
39
  worker_thread+0x189/0x13c0 kernel/workqueue.c:2296
34
37
38
31
36
31
39
'
  kthread+0x35a/0x420 kernel/kthread.c:246
FS-Cache: Duplicate cookie detected
  ret_from_fork+0x3a/0x50 arch/x86/entry/entry_64.S:413
Modules linked in:
Dumping ftrace buffer:
    (ftrace buffer empty)
---[ end trace c3e56d8d2cc1f8a2 ]---
FS-Cache: O-cookie c=000000008e4eb276 [p=000000002fd7b0b4 fl=222 nc=0 na=1]
RIP: 0010:__list_add_valid.cold.0+0x23/0x25 lib/list_debug.c:26
FS-Cache: O-cookie d=0000000068a887e4 n=00000000257e8f2f
Code: e8 4f 2b 5a fe eb 97 48 89 d9 48 c7 c7 60 b2 3a 87 e8 62 05 02 fe 0f  
0b 48 89 f1 48 c7 c7 20 b3 3a 87 48 89 de e8 4e 05 02 fe <0f> 0b 4c 89 e2  
48 89 de 48 c7 c7 60 b4 3a 87 e8 3a 05 02 fe 0f 0b
FS-Cache: O-key=[10] '
RSP: 0018:ffff8801d9f17590 EFLAGS: 00010282
34
32
RAX: 0000000000000075 RBX: ffff8801c5b17ab0 RCX: 0000000000000000
39
RDX: 0000000000000000 RSI: ffffffff8163ac01 RDI: 0000000000000001
34
RBP: ffff8801d9f175a8 R08: ffff8801d9f06340 R09: ffffed003b605010
37
R10: ffffed003b605010 R11: ffff8801db028087 R12: ffff8801a92d1b58
38
R13: ffff8801a92d1b58 R14: ffff8801c5b17b04 R15: ffff8801a92d1b58
31
FS:  0000000000000000(0000) GS:ffff8801db000000(0000) knlGS:0000000000000000
36
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
3139'
CR2: 00000000006dc138 CR3: 00000001c845c000 CR4: 00000000001406f0
FS-Cache: N-cookie c=00000000c3d88b67 [p=000000002fd7b0b4 fl=2 nc=0 na=1]
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
FS-Cache: N-cookie d=0000000068a887e4 n=00000000c137bf7f
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
FS-Cache: N-key=[10] '