------------[ cut here ]------------
refcnt < 0
WARNING: net/bluetooth/hci_conn.c:567 at hci_conn_timeout+0x16a/0x230 net/bluetooth/hci_conn.c:567, CPU#3: kworker/u33:1/5287
Modules linked in:
CPU: 3 UID: 0 PID: 5287 Comm: kworker/u33:1 Not tainted syzkaller #0 PREEMPT(full) 
Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS 1.16.3-debian-1.16.3-2 04/01/2014
Workqueue: hci1 hci_conn_timeout
RIP: 0010:hci_conn_timeout+0x16a/0x230 net/bluetooth/hci_conn.c:567
Code: 44 0f b6 2d bb fb 4d 06 31 ff 41 83 e5 40 44 89 ee e8 0a 8e 81 f7 45 84 ed 0f 84 02 ff ff ff e9 06 a1 ea f6 e8 a7 93 81 f7 90 <0f> 0b 90 e8 9e 93 81 f7 48 8d bb fd f5 ff ff 48 b8 00 00 00 00 00
RSP: 0018:ffffc90022d4fc18 EFLAGS: 00010293
RAX: 0000000000000000 RBX: ffff88802995ca40 RCX: ffffffff8a870a1f
RDX: ffff88802bce2480 RSI: ffffffff8a870b19 RDI: ffff88802bce2480
RBP: 00000000ffffffff R08: 0000000000000005 R09: 0000000000000000
R10: 00000000ffffffff R11: 000000000000760b R12: ffff88802995c000
R13: ffff88802bce2904 R14: ffffffff90d9ae04 R15: 0000000000000000
FS:  0000000000000000(0000) GS:ffff8880d6647000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 0000200000000040 CR3: 000000002c5b3000 CR4: 0000000000352ef0
Call Trace:
 <TASK>
 process_one_work+0x9d7/0x1920 kernel/workqueue.c:3275
 process_scheduled_works kernel/workqueue.c:3358 [inline]
 worker_thread+0x5da/0xe40 kernel/workqueue.c:3439
 kthread+0x370/0x450 kernel/kthread.c:467
 ret_from_fork+0x754/0xd80 arch/x86/kernel/process.c:158
 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:245
 </TASK>