INFO: trying to register non-static key.
the code is fine but needs lockdep annotation.
turning off the locking correctness validator.
CPU: 0 PID: 9991 Comm: kworker/0:12 Not tainted 5.8.0-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
Workqueue: events l2cap_chan_timeout
Call Trace:
 __dump_stack lib/dump_stack.c:77 [inline]
 dump_stack+0x18f/0x20d lib/dump_stack.c:118
 assign_lock_key kernel/locking/lockdep.c:894 [inline]
 register_lock_class+0x157d/0x1630 kernel/locking/lockdep.c:1206
 __lock_acquire+0xf9/0x5640 kernel/locking/lockdep.c:4305
 lock_acquire+0x1f1/0xad0 kernel/locking/lockdep.c:5005
 __raw_spin_lock_bh include/linux/spinlock_api_smp.h:135 [inline]
 _raw_spin_lock_bh+0x2f/0x40 kernel/locking/spinlock.c:175
 spin_lock_bh include/linux/spinlock.h:359 [inline]
 lock_sock_nested+0x3b/0x110 net/core/sock.c:3048
 l2cap_sock_teardown_cb+0x88/0x400 net/bluetooth/l2cap_sock.c:1520
 l2cap_chan_del+0xad/0x1300 net/bluetooth/l2cap_core.c:618
 l2cap_chan_close+0x118/0xb10 net/bluetooth/l2cap_core.c:823
 l2cap_chan_timeout+0x173/0x450 net/bluetooth/l2cap_core.c:436
 process_one_work+0x94c/0x1670 kernel/workqueue.c:2269
 worker_thread+0x64c/0x1120 kernel/workqueue.c:2415
 kthread+0x3b5/0x4a0 kernel/kthread.c:292
 ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:294
BUG: kernel NULL pointer dereference, address: 0000000000000000
#PF: supervisor instruction fetch in kernel mode
#PF: error_code(0x0010) - not-present page
PGD 8d60d067 P4D 8d60d067 PUD 8d60e067 PMD 0 
Oops: 0010 [#1] PREEMPT SMP KASAN
CPU: 0 PID: 9991 Comm: kworker/0:12 Not tainted 5.8.0-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
Workqueue: events l2cap_chan_timeout
RIP: 0010:0x0
Code: Bad RIP value.
RSP: 0018:ffffc90006597b60 EFLAGS: 00010246
RAX: dffffc0000000000 RBX: ffff88809aa6c000 RCX: ffffffff872c4a2f
RDX: 1ffff11013bda08c RSI: ffffffff872c4c7c RDI: ffff88809ded0000
RBP: 0000000000000005 R08: 0000000000000001 R09: ffff88809ded0067
R10: 0000000000000009 R11: 0000000000000001 R12: 000000000000006f
R13: ffff88809ded0000 R14: 0000000000000000 R15: 0000000000000005
FS:  0000000000000000(0000) GS:ffff8880ae600000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: ffffffffffffffd6 CR3: 000000008d60c000 CR4: 00000000001506f0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
Call Trace:
 l2cap_sock_teardown_cb+0x374/0x400 net/bluetooth/l2cap_sock.c:1547
 l2cap_chan_del+0xad/0x1300 net/bluetooth/l2cap_core.c:618
 l2cap_chan_close+0x118/0xb10 net/bluetooth/l2cap_core.c:823
 l2cap_chan_timeout+0x173/0x450 net/bluetooth/l2cap_core.c:436
 process_one_work+0x94c/0x1670 kernel/workqueue.c:2269
 worker_thread+0x64c/0x1120 kernel/workqueue.c:2415
 kthread+0x3b5/0x4a0 kernel/kthread.c:292
 ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:294
Modules linked in:
CR2: 0000000000000000
---[ end trace 18d9278b96464d42 ]---
RIP: 0010:0x0
Code: Bad RIP value.
RSP: 0018:ffffc90006597b60 EFLAGS: 00010246
RAX: dffffc0000000000 RBX: ffff88809aa6c000 RCX: ffffffff872c4a2f
RDX: 1ffff11013bda08c RSI: ffffffff872c4c7c RDI: ffff88809ded0000
RBP: 0000000000000005 R08: 0000000000000001 R09: ffff88809ded0067
R10: 0000000000000009 R11: 0000000000000001 R12: 000000000000006f
R13: ffff88809ded0000 R14: 0000000000000000 R15: 0000000000000005
FS:  0000000000000000(0000) GS:ffff8880ae600000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: ffffffffffffffd6 CR3: 000000008d60c000 CR4: 00000000001506f0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400