general protection fault in l2cap_chan_timeout (2)

[syzbot]

Hello,

syzbot found the following issue on:

HEAD commit: a35d65bedfbc Linux 4.14.267
git tree: linux-4.14.y
console output: https://syzkaller.appspot.com/x/log.txt?x=1600be86700000
kernel config: https://syzkaller.appspot.com/x/.config?x=8535d773e783c59a
dashboard link: https://syzkaller.appspot.com/bug?extid=f434eceb57e3b17b85d0
compiler: gcc version 10.2.1 20210110 (Debian 10.2.1-6)
syz repro: https://syzkaller.appspot.com/x/repro.syz?x=11f02586700000
C reproducer: https://syzkaller.appspot.com/x/repro.c?x=1080b1a6700000

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+f434ec...@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] PREEMPT SMP KASAN
Modules linked in:
CPU: 0 PID: 12086 Comm: kworker/0:1 Not tainted 4.14.267-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
Workqueue: events l2cap_chan_timeout
task: ffff888096cdc580 task.stack: ffff88809b2e0000
RIP: 0010:__lock_acquire+0x1cc/0x3f20 kernel/locking/lockdep.c:3369
RSP: 0018:ffff88809b2e79b0 EFLAGS: 00010002
RAX: dffffc0000000000 RBX: 0000000000000000 RCX: 0000000000000000
RDX: 0000000000000054 RSI: 0000000000000000 RDI: 00000000000002a0
RBP: 0000000000000000 R08: 0000000000000001 R09: 0000000000000000
R10: 0000000000000001 R11: ffff888096cdc580 R12: 00000000000002a0
R13: 0000000000000000 R14: 0000000000000001 R15: ffffffff8beced40
FS: 0000000000000000(0000) GS:ffff8880ba400000(0000) knlGS:0000000000000000
CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 0000000020000140 CR3: 00000000a1efa000 CR4: 00000000003406f0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
Call Trace:
lock_acquire+0x170/0x3f0 kernel/locking/lockdep.c:3998
__mutex_lock_common kernel/locking/mutex.c:756 [inline]
__mutex_lock+0xc4/0x1310 kernel/locking/mutex.c:893
l2cap_chan_timeout+0x60/0x2a0 net/bluetooth/l2cap_core.c:416
process_one_work+0x793/0x14a0 kernel/workqueue.c:2117
worker_thread+0x5cc/0xff0 kernel/workqueue.c:2251
kthread+0x30d/0x420 kernel/kthread.c:232
ret_from_fork+0x24/0x30 arch/x86/entry/entry_64.S:404
Code: 18 00 00 00 00 48 81 c4 80 01 00 00 44 89 e8 5b 5d 41 5c 41 5d 41 5e 41 5f c3 48 b8 00 00 00 00 00 fc ff df 4c 89 e2 48 c1 ea 03 <80> 3c 02 00 0f 85 67 2a 00 00 49 81 3c 24 a0 a7 2f 8b 0f 84 5f
RIP: __lock_acquire+0x1cc/0x3f20 kernel/locking/lockdep.c:3369 RSP: ffff88809b2e79b0
---[ end trace fdc2701fdf82f6a8 ]---
----------------
Code disassembly (best guess), 1 bytes skipped:
0: 00 00 add %al,(%rax)
2: 00 00 add %al,(%rax)
4: 48 81 c4 80 01 00 00 add $0x180,%rsp
b: 44 89 e8 mov %r13d,%eax
e: 5b pop %rbx
f: 5d pop %rbp
10: 41 5c pop %r12
12: 41 5d pop %r13
14: 41 5e pop %r14
16: 41 5f pop %r15
18: c3 retq
19: 48 b8 00 00 00 00 00 movabs $0xdffffc0000000000,%rax
20: fc ff df
23: 4c 89 e2 mov %r12,%rdx
26: 48 c1 ea 03 shr $0x3,%rdx
* 2a: 80 3c 02 00 cmpb $0x0,(%rdx,%rax,1) <-- trapping instruction
2e: 0f 85 67 2a 00 00 jne 0x2a9b
34: 49 81 3c 24 a0 a7 2f cmpq $0xffffffff8b2fa7a0,(%r12)
3b: 8b
3c: 0f .byte 0xf
3d: 84 .byte 0x84
3e: 5f pop %rdi


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