------------[ cut here ]------------
refcount_t: underflow; use-after-free.
WARNING: CPU: 0 PID: 8005 at lib/refcount.c:28 refcount_warn_saturate+0x11a/0x1d0
Modules linked in:
CPU: 0 UID: 0 PID: 8005 Comm: syz-executor Not tainted syzkaller #0 PREEMPT(full) 
Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS 1.16.2-debian-1.16.2-1 04/01/2014
RIP: 0010:refcount_warn_saturate+0x11a/0x1d0
Code: 80 b3 e2 8b e8 67 26 bb fc 90 0f 0b 90 90 eb d7 e8 4b 8a f7 fc c6 05 92 5e c5 0a 01 90 48 c7 c7 e0 b3 e2 8b e8 47 26 bb fc 90 <0f> 0b 90 90 eb b7 e8 2b 8a f7 fc c6 05 6f 5e c5 0a 01 90 48 c7 c7
RSP: 0018:ffffc900071f7578 EFLAGS: 00010246
RAX: b254662c1a6c4b00 RBX: 0000000000000003 RCX: ffff88811b7b1cc0
RDX: 0000000000000000 RSI: 0000000000000000 RDI: 0000000000000002
RBP: 0000000000000000 R08: 0000000000000003 R09: 0000000000000004
R10: dffffc0000000000 R11: fffffbfff1bfa1f4 R12: ffff88802a1eec00
R13: ffff88810f75ac60 R14: ffff88810f75ac78 R15: dffffc0000000000
FS:  000055557e195500(0000) GS:ffff8880b8614000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007f89c5c8f000 CR3: 000000000df36000 CR4: 00000000000006f0
Call Trace:
 <TASK>
 klist_dec_and_del+0x3c7/0x3d0
 klist_remove+0x1bd/0x340
 device_move+0x193/0x700
 hci_conn_del_sysfs+0xb8/0x170
 hci_conn_del+0xc33/0x11b0
 hci_conn_hash_flush+0x191/0x230
 hci_dev_close_sync+0xaef/0x1330
 hci_unregister_dev+0x21a/0x510
 vhci_release+0x152/0x1a0
 __fput+0x44c/0xa70
 task_work_run+0x1d4/0x260
 do_exit+0x6b5/0x2300
 do_group_exit+0x21c/0x2d0
 get_signal+0x1286/0x1340
 arch_do_signal_or_restart+0x9a/0x750
 exit_to_user_mode_loop+0x75/0x110
 do_syscall_64+0x2bd/0x3b0
 entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7fb1165c1465
Code: Unable to access opcode bytes at 0x7fb1165c143b.
RSP: 002b:00007ffdf4a3ac00 EFLAGS: 00000293 ORIG_RAX: 00000000000000e6
RAX: 0000000000000000 RBX: 0000000000002ee2 RCX: 00007fb1165c1465
RDX: 00007ffdf4a3ac40 RSI: 0000000000000000 RDI: 0000000000000000
RBP: 00007ffdf4a3acac R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000293 R12: 0000000000001388
R13: 00000000000927c0 R14: 0000000000157e38 R15: 00007ffdf4a3ad00
 </TASK>
