[syzbot] general protection fault in l2cap_chan_timeout (2)

[syzbot]

Hello,

syzbot found the following issue on:

HEAD commit:    ad9f25d3 Merge tag 'netfs-lib-fixes-20200525' of git://git..
git tree:       upstream
console output: https://syzkaller.appspot.com/x/log.txt?x=173d383dd00000
kernel config:  https://syzkaller.appspot.com/x/.config?x=266cda122a0b56c
dashboard link: https://syzkaller.appspot.com/bug?extid=008cdbf7a9044c2c2f99

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

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+008cdbf7a9044c2c2f99@xxxxxxxxxxxxxxxxxxxxxxxxx

general protection fault, probably for non-canonical address 0xdffffc000000005a: 0000 [#1] PREEMPT SMP KASAN
KASAN: null-ptr-deref in range [0x00000000000002d0-0x00000000000002d7]
CPU: 0 PID: 8 Comm: kworker/0:2 Not tainted 5.13.0-rc3-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
Workqueue: events l2cap_chan_timeout
RIP: 0010:__mutex_lock_common kernel/locking/mutex.c:941 [inline]
RIP: 0010:__mutex_lock+0xf6/0x10c0 kernel/locking/mutex.c:1104
Code: d0 7c 08 84 d2 0f 85 cc 0c 00 00 8b 15 e3 55 5f 07 85 d2 75 29 48 8d 7d 60 48 b8 00 00 00 00 00 fc ff df 48 89 fa 48 c1 ea 03 <80> 3c 02 00 0f 85 db 0e 00 00 48 3b 6d 60 0f 85 5a 0a 00 00 bf 01
RSP: 0018:ffffc90000cd7b78 EFLAGS: 00010216
RAX: dffffc0000000000 RBX: 0000000000000000 RCX: 0000000000000001
RDX: 000000000000005a RSI: 0000000000000000 RDI: 00000000000002d0
RBP: 0000000000000270 R08: ffffffff880a40d9 R09: 0000000000000000
R10: ffffffff814b4be0 R11: 0000000000000000 R12: 0000000000000000
R13: dffffc0000000000 R14: ffff888072e47020 R15: ffff8880b9c34a40
FS:  0000000000000000(0000) GS:ffff8880b9c00000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007fcac15f1d58 CR3: 00000000628fa000 CR4: 0000000000350ef0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000ffff0ff0 DR7: 0000000000000600
Call Trace:
 l2cap_chan_timeout+0x69/0x2f0 net/bluetooth/l2cap_core.c:422
 process_one_work+0x98d/0x1600 kernel/workqueue.c:2276
 worker_thread+0x64c/0x1120 kernel/workqueue.c:2422
 kthread+0x3b1/0x4a0 kernel/kthread.c:313
 ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:294
Modules linked in:
---[ end trace d3dc393d48928266 ]---
RIP: 0010:__mutex_lock_common kernel/locking/mutex.c:941 [inline]
RIP: 0010:__mutex_lock+0xf6/0x10c0 kernel/locking/mutex.c:1104
Code: d0 7c 08 84 d2 0f 85 cc 0c 00 00 8b 15 e3 55 5f 07 85 d2 75 29 48 8d 7d 60 48 b8 00 00 00 00 00 fc ff df 48 89 fa 48 c1 ea 03 <80> 3c 02 00 0f 85 db 0e 00 00 48 3b 6d 60 0f 85 5a 0a 00 00 bf 01
RSP: 0018:ffffc90000cd7b78 EFLAGS: 00010216
RAX: dffffc0000000000 RBX: 0000000000000000 RCX: 0000000000000001
RDX: 000000000000005a RSI: 0000000000000000 RDI: 00000000000002d0
RBP: 0000000000000270 R08: ffffffff880a40d9 R09: 0000000000000000
R10: ffffffff814b4be0 R11: 0000000000000000 R12: 0000000000000000
R13: dffffc0000000000 R14: ffff888072e47020 R15: ffff8880b9c34a40
FS:  0000000000000000(0000) GS:ffff8880b9c00000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 0000001b33621000 CR3: 00000000628fa000 CR4: 0000000000350ef0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000ffff0ff0 DR7: 0000000000000600


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