INFO: trying to register non-static key.
The code is fine but needs lockdep annotation, or maybe
EXT4-fs (loop5): VFS: Can't find ext4 filesystem
you didn't initialize this object before use?
turning off the locking correctness validator.
CPU: 1 PID: 3550 Comm: kworker/1:2 Not tainted 4.19.201-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+0x1fc/0x2ef lib/dump_stack.c:118
 assign_lock_key kernel/locking/lockdep.c:728 [inline]
 register_lock_class+0xe82/0x11c0 kernel/locking/lockdep.c:754
 __lock_acquire+0x17d/0x3ff0 kernel/locking/lockdep.c:3304
 lock_acquire+0x170/0x3c0 kernel/locking/lockdep.c:3908
 __raw_spin_lock_bh include/linux/spinlock_api_smp.h:135 [inline]
 _raw_spin_lock_bh+0x2f/0x40 kernel/locking/spinlock.c:168
 spin_lock_bh include/linux/spinlock.h:334 [inline]
 lock_sock_nested+0x3b/0x110 net/core/sock.c:2864
 l2cap_sock_teardown_cb+0xa0/0x6d0 net/bluetooth/l2cap_sock.c:1348
 l2cap_chan_del+0xbc/0xa50 net/bluetooth/l2cap_core.c:603
 l2cap_chan_close+0x1b5/0x950 net/bluetooth/l2cap_core.c:761
 l2cap_chan_timeout+0x17e/0x2f0 net/bluetooth/l2cap_core.c:430
 process_one_work+0x864/0x1570 kernel/workqueue.c:2153
 worker_thread+0x64c/0x1130 kernel/workqueue.c:2296
 kthread+0x33f/0x460 kernel/kthread.c:259
 ret_from_fork+0x24/0x30 arch/x86/entry/entry_64.S:415
BUG: unable to handle kernel NULL pointer dereference at 0000000000000000
PGD ab76b067 P4D ab76b067 PUD ade51067 PMD 0 
Oops: 0010 [#1] PREEMPT SMP KASAN
CPU: 1 PID: 3550 Comm: kworker/1:2 Not tainted 4.19.201-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
Workqueue: events l2cap_chan_timeout
RIP: 0010:          (null)
Code: Bad RIP value.
RSP: 0018:ffff8880a92cfbb0 EFLAGS: 00010246
RAX: dffffc0000000000 RBX: 0000000000000000 RCX: ffffffff87438aa5
RDX: 1ffff11015f2a0c9 RSI: ffffffff87438e94 RDI: ffff8880af950240
RBP: 000000000000006f R08: 0000000000000000 R09: 0000000000000009
R10: 0000000000000001 R11: ffffffff8c66405b R12: ffff8880ab8a341c
R13: ffff8880af950240 R14: ffff8880ab8a3400 R15: 0000000000000005
FS:  0000000000000000(0000) GS:ffff8880ba100000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: ffffffffffffffd6 CR3: 00000000a5a63000 CR4: 00000000001426e0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
Call Trace:
 l2cap_sock_teardown_cb+0x4f0/0x6d0 net/bluetooth/l2cap_sock.c:1373
 l2cap_chan_del+0xbc/0xa50 net/bluetooth/l2cap_core.c:603
 l2cap_chan_close+0x1b5/0x950 net/bluetooth/l2cap_core.c:761
 l2cap_chan_timeout+0x17e/0x2f0 net/bluetooth/l2cap_core.c:430
 process_one_work+0x864/0x1570 kernel/workqueue.c:2153
 worker_thread+0x64c/0x1130 kernel/workqueue.c:2296
 kthread+0x33f/0x460 kernel/kthread.c:259
 ret_from_fork+0x24/0x30 arch/x86/entry/entry_64.S:415
Modules linked in:
CR2: 0000000000000000
---[ end trace 735e797a07795ec8 ]---
RIP: 0010:          (null)
Code: Bad RIP value.
RSP: 0018:ffff8880a92cfbb0 EFLAGS: 00010246
RAX: dffffc0000000000 RBX: 0000000000000000 RCX: ffffffff87438aa5
RDX: 1ffff11015f2a0c9 RSI: ffffffff87438e94 RDI: ffff8880af950240
RBP: 000000000000006f R08: 0000000000000000 R09: 0000000000000009
R10: 0000000000000001 R11: ffffffff8c66405b R12: ffff8880ab8a341c
R13: ffff8880af950240 R14: ffff8880ab8a3400 R15: 0000000000000005
FS:  0000000000000000(0000) GS:ffff8880ba100000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: ffffffffffffffd6 CR3: 00000000a5a63000 CR4: 00000000001426e0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400