BUG: corrupted list in p9_conn_cancel

[syzbot]

Hello,

syzbot found the following crash on:

HEAD commit: f6e27dbb Linux 4.14.146
git tree: linux-4.14.y
console output: https://syzkaller.appspot.com/x/log.txt?x=142c11cb600000
kernel config: https://syzkaller.appspot.com/x/.config?x=cb75afefe94a0801
dashboard link: https://syzkaller.appspot.com/bug?extid=1dfe737f13edb00a42cb
compiler: gcc (GCC) 9.0.0 20181231 (experimental)

Unfortunately, I don't have any reproducer for this crash yet.

IMPORTANT: if you fix the bug, please add the following tag to the commit:
Reported-by: syzbot+1dfe73...@syzkaller.appspotmail.com

list_add corruption. next->prev should be prev (ffff88805d9c7ca8), but was
ffff8880913cfd80. (next=ffff88808d2d93d8).
------------[ cut here ]------------
kernel BUG at lib/list_debug.c:23!
invalid opcode: 0000 [#1] PREEMPT SMP KASAN
Modules linked in:
netlink: 8 bytes leftover after parsing attributes in process
`syz-executor.0'.
CPU: 1 PID: 6920 Comm: kworker/1:3 Not tainted 4.14.146 #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS
Google 01/01/2011
Workqueue: events p9_poll_workfn
task: ffff88805d9ba400 task.stack: ffff88805d9c0000
RIP: 0010:__list_add_valid.cold+0xf/0x3c lib/list_debug.c:23
RSP: 0018:ffff88805d9c7c20 EFLAGS: 00010286
RAX: 0000000000000075 RBX: ffff88805d9c7ca8 RCX: 0000000000000000
RDX: 0000000000000000 RSI: ffffffff866d10e0 RDI: ffffed100bb38f7a
RBP: ffff88805d9c7c38 R08: 0000000000000075 R09: ffff88805d9bacf0
R10: 0000000000000000 R11: 0000000000000000 R12: ffff88808d2d93d8
R13: ffff88805d9c7ca8 R14: ffff88808d2d93b0 R15: ffff88808d2d93d8
FS: 0000000000000000(0000) GS:ffff8880aef00000(0000) knlGS:0000000000000000
CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007f4dc7c1c000 CR3: 0000000080786000 CR4: 00000000001406e0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
Call Trace:
__list_add include/linux/list.h:60 [inline]
list_add include/linux/list.h:79 [inline]
list_move include/linux/list.h:171 [inline]
p9_conn_cancel+0x1e3/0x880 net/9p/trans_fd.c:216
p9_poll_mux net/9p/trans_fd.c:632 [inline]
p9_poll_workfn+0x27e/0x3e0 net/9p/trans_fd.c:1123
process_one_work+0x863/0x1600 kernel/workqueue.c:2114
worker_thread+0x5d9/0x1050 kernel/workqueue.c:2248
kthread+0x319/0x430 kernel/kthread.c:232
ret_from_fork+0x24/0x30 arch/x86/entry/entry_64.S:404
Code: 1d ae fe eb d5 4c 89 e7 e8 0a 1d ae fe eb a3 4c 89 f7 e8 00 1d ae fe
e9 56 ff ff ff 4c 89 e1 48 c7 c7 80 30 9d 86 e8 4f a8 72 fe <0f> 0b 48 89
f2 4c 89 e1 4c 89 ee 48 c7 c7 c0 31 9d 86 e8 38 a8
RIP: __list_add_valid.cold+0xf/0x3c lib/list_debug.c:23 RSP:
ffff88805d9c7c20
---[ end trace 5073ed828037e0d8 ]---


---
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[syzbot]

syzbot has found a reproducer for the following crash on:

HEAD commit: ddef1e8e Linux 4.14.151
git tree: linux-4.14.y
console output: https://syzkaller.appspot.com/x/log.txt?x=11e36524e00000
kernel config: https://syzkaller.appspot.com/x/.config?x=a2b317f0c5f02ed3

dashboard link: https://syzkaller.appspot.com/bug?extid=1dfe737f13edb00a42cb
compiler: gcc (GCC) 9.0.0 20181231 (experimental)

syz repro: https://syzkaller.appspot.com/x/repro.syz?x=1619fc8f600000

IMPORTANT: if you fix the bug, please add the following tag to the commit:
Reported-by: syzbot+1dfe73...@syzkaller.appspotmail.com

IPv6: ADDRCONF(NETDEV_CHANGE): hsr0: link becomes ready
IPv6: ADDRCONF(NETDEV_UP): vxcan1: link is not ready
8021q: adding VLAN 0 to HW filter on device batadv0
list_add corruption. next->prev should be prev (ffff8880a95d7ca8), but was
ffff8880a08f07c0. (next=ffff888097a09ad8).

------------[ cut here ]------------
kernel BUG at lib/list_debug.c:23!
invalid opcode: 0000 [#1] PREEMPT SMP KASAN
Modules linked in:

CPU: 0 PID: 277 Comm: kworker/0:1 Not tainted 4.14.151 #0

Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS
Google 01/01/2011
Workqueue: events p9_poll_workfn

task: ffff8880a9596200 task.stack: ffff8880a95d0000

RIP: 0010:__list_add_valid.cold+0xf/0x3c lib/list_debug.c:23

RSP: 0018:ffff8880a95d7c20 EFLAGS: 00010286
RAX: 0000000000000075 RBX: ffff8880a95d7ca8 RCX: 0000000000000000
RDX: 0000000000000000 RSI: ffffffff866d1160 RDI: ffffed10152baf7a
RBP: ffff8880a95d7c38 R08: 0000000000000075 R09: ffff8880a9596af0
R10: 0000000000000000 R11: 0000000000000000 R12: ffff888097a09ad8
R13: ffff8880a95d7ca8 R14: ffff888097a09ab0 R15: ffff888097a09ad8
FS: 0000000000000000(0000) GS:ffff8880aee00000(0000) knlGS:0000000000000000

CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033

CR2: 00007f50501a4000 CR3: 000000009a707000 CR4: 00000000001406f0

DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
Call Trace:
__list_add include/linux/list.h:60 [inline]
list_add include/linux/list.h:79 [inline]
list_move include/linux/list.h:171 [inline]
p9_conn_cancel+0x1e3/0x880 net/9p/trans_fd.c:216
p9_poll_mux net/9p/trans_fd.c:632 [inline]
p9_poll_workfn+0x27e/0x3e0 net/9p/trans_fd.c:1123
process_one_work+0x863/0x1600 kernel/workqueue.c:2114
worker_thread+0x5d9/0x1050 kernel/workqueue.c:2248
kthread+0x319/0x430 kernel/kthread.c:232
ret_from_fork+0x24/0x30 arch/x86/entry/entry_64.S:404

Code: 3b ae fe eb d5 4c 89 e7 e8 8a 3b ae fe eb a3 4c 89 f7 e8 80 3b ae fe
e9 56 ff ff ff 4c 89 e1 48 c7 c7 a0 33 9d 86 e8 df c4 72 fe <0f> 0b 48 89
f2 4c 89 e1 4c 89 ee 48 c7 c7 e0 34 9d 86 e8 c8 c4

RIP: __list_add_valid.cold+0xf/0x3c lib/list_debug.c:23 RSP:

ffff8880a95d7c20
---[ end trace 65aa45f043ec2865 ]---