general protection fault in p9_conn_cancel

general protection fault in p9_conn_cancel

[syzbot]

Hello,

syzbot found the following crash on:

HEAD commit:    30c2c32d7f70 Merge tag 'drm-fixes-2018-07-10' of git://ano..
git tree:       upstream
console output: https://syzkaller.appspot.com/x/log.txt?x=15e7aa78400000
kernel config:  https://syzkaller.appspot.com/x/.config?x=25856fac4e580aa7
dashboard link: https://syzkaller.appspot.com/bug?extid=4d29d76a0da7a8c4d86c
compiler:       gcc (GCC) 8.0.1 20180413 (experimental)
syzkaller repro:https://syzkaller.appspot.com/x/repro.syz?x=10e2c5b2400000
C reproducer:   https://syzkaller.appspot.com/x/repro.c?x=179415b2400000

IMPORTANT: if you fix the bug, please add the following tag to the commit:
Reported-by: syzbot+4d29d76a0da7a8c4d86c@syzkaller.appspotmail.com

kasan: CONFIG_KASAN_INLINE enabled
kasan: GPF could be caused by NULL-ptr deref or user memory access
general protection fault: 0000 [#1] SMP KASAN
CPU: 1 PID: 2133 Comm: kworker/1:2 Not tainted 4.18.0-rc4+ #140
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS  
Google 01/01/2011
Workqueue: events p9_poll_workfn
RIP: 0010:__lock_acquire+0x245/0x5020 kernel/locking/lockdep.c:3314
Code: 28 00 00 00 0f 85 03 34 00 00 48 8d 65 d8 5b 41 5c 41 5d 41 5e 41 5f  
5d c3 48 b8 00 00 00 00 00 fc ff df 4c 89 ea 48 c1 ea 03 <80> 3c 02 00 0f  
85 c6 35 00 00 49 81 7d 00 60 86 e7 89 0f 84 42 ff
RSP: 0018:ffff8801cd546e60 EFLAGS: 00010006
RAX: dffffc0000000000 RBX: 0000000000000000 RCX: 0000000000000000
RDX: 0000000000000003 RSI: 0000000000000000 RDI: ffffffff88f1b060
RBP: ffff8801cd5471e8 R08: 0000000000000001 R09: 0000000000000001
R10: ffffed003ac9b825 R11: 0000000000000001 R12: 0000000000000001
R13: 0000000000000018 R14: ffff8801cd4f4680 R15: 0000000000000000
FS:  0000000000000000(0000) GS:ffff8801daf00000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00000000203b9fdc CR3: 00000001ab7f9000 CR4: 00000000001406e0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
Call Trace:
  lock_acquire+0x1e4/0x540 kernel/locking/lockdep.c:3924
  __raw_spin_lock_irqsave include/linux/spinlock_api_smp.h:110 [inline]
  _raw_spin_lock_irqsave+0x96/0xc0 kernel/locking/spinlock.c:152
  p9_conn_cancel+0x166/0xd30 net/9p/trans_fd.c:205
  p9_poll_mux net/9p/trans_fd.c:620 [inline]
  p9_poll_workfn+0x4b2/0x6d0 net/9p/trans_fd.c:1107
  process_one_work+0xc73/0x1ba0 kernel/workqueue.c:2153
  worker_thread+0x189/0x13c0 kernel/workqueue.c:2296
  kthread+0x345/0x410 kernel/kthread.c:246
  ret_from_fork+0x3a/0x50 arch/x86/entry/entry_64.S:412
Modules linked in:
Dumping ftrace buffer:
    (ftrace buffer empty)
---[ end trace 7b21d69ebadc8360 ]---
RIP: 0010:__lock_acquire+0x245/0x5020 kernel/locking/lockdep.c:3314
Code: 28 00 00 00 0f 85 03 34 00 00 48 8d 65 d8 5b 41 5c 41 5d 41 5e 41 5f  
5d c3 48 b8 00 00 00 00 00 fc ff df 4c 89 ea 48 c1 ea 03 <80> 3c 02 00 0f  
85 c6 35 00 00 49 81 7d 00 60 86 e7 89 0f 84 42 ff
RSP: 0018:ffff8801cd546e60 EFLAGS: 00010006
RAX: dffffc0000000000 RBX: 0000000000000000 RCX: 0000000000000000
RDX: 0000000000000003 RSI: 0000000000000000 RDI: ffffffff88f1b060
RBP: ffff8801cd5471e8 R08: 0000000000000001 R09: 0000000000000001
R10: ffffed003ac9b825 R11: 0000000000000001 R12: 0000000000000001
R13: 0000000000000018 R14: ffff8801cd4f4680 R15: 0000000000000000
FS:  0000000000000000(0000) GS:ffff8801daf00000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00000000203b9fdc CR3: 00000001ab7f9000 CR4: 00000000001406e0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400


---
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Re: general protection fault in p9_conn_cancel

[syzbot]

syzbot suspects this bug was fixed by commit:

commit 9f476d7c540cb57556d3cc7e78704e6cd5100f5f
Author: Tomas Bortoli <tomasbortoli@gmail.com>
Date:   Mon Jul 23 18:42:53 2018 +0000

     net/9p/trans_fd.c: fix race by holding the lock

bisection log:  https://syzkaller.appspot.com/x/bisect.txt?x=1150b430600000
start commit:   30c2c32d Merge tag 'drm-fixes-2018-07-10' of git://anongit..
git tree:       upstream
kernel config:  https://syzkaller.appspot.com/x/.config?x=25856fac4e580aa7
dashboard link: https://syzkaller.appspot.com/bug?extid=4d29d76a0da7a8c4d86c
syz repro:      https://syzkaller.appspot.com/x/repro.syz?x=10e2c5b2400000
C reproducer:   https://syzkaller.appspot.com/x/repro.c?x=179415b2400000

If the result looks correct, please mark the bug fixed by replying with:

#syz fix: net/9p/trans_fd.c: fix race by holding the lock

For information about bisection process see: https://goo.gl/tpsmEJ#bisection