------------[ cut here ]------------
refcount_t: underflow; use-after-free.
WARNING: CPU: 0 PID: 5947 at lib/refcount.c:28 refcount_warn_saturate+0x14a/0x210 lib/refcount.c:28
Modules linked in:
CPU: 0 UID: 0 PID: 5947 Comm: kworker/u33:7 Not tainted syzkaller #0 PREEMPT(full) 
Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS 1.16.3-debian-1.16.3-2~bpo12+1 04/01/2014
Workqueue: hci1 hci_cmd_sync_work
RIP: 0010:refcount_warn_saturate+0x14a/0x210 lib/refcount.c:28
Code: ff 89 de e8 a8 57 18 fd 84 db 0f 85 66 ff ff ff e8 bb 5c 18 fd c6 05 09 d3 c5 0b 01 90 48 c7 c7 80 ba ef 8b e8 a7 8f d6 fc 90 <0f> 0b 90 90 e9 43 ff ff ff e8 98 5c 18 fd 0f b6 1d e4 d2 c5 0b 31
RSP: 0018:ffffc90003dc78b8 EFLAGS: 00010282
RAX: 0000000000000000 RBX: 0000000000000000 RCX: ffffffff817b3ee8
RDX: ffff88803074a480 RSI: ffffffff817b3ef5 RDI: 0000000000000001
RBP: ffff888054006478 R08: 0000000000000001 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000001 R12: ffff8880531b4800
R13: ffff888054006478 R14: ffffffff85daa1d0 R15: ffffffff906539e0
FS:  0000000000000000(0000) GS:ffff8880d6a0a000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 0000000000000000 CR3: 000000005000d000 CR4: 0000000000352ef0
Call Trace:
 <TASK>
 __refcount_sub_and_test include/linux/refcount.h:400 [inline]
 __refcount_dec_and_test include/linux/refcount.h:432 [inline]
 refcount_dec_and_test include/linux/refcount.h:450 [inline]
 kref_put include/linux/kref.h:64 [inline]
 klist_dec_and_del lib/klist.c:206 [inline]
 klist_put+0x11b/0x1b0 lib/klist.c:217
 klist_del lib/klist.c:230 [inline]
 klist_remove+0x13f/0x2e0 lib/klist.c:249
 device_move+0x12d/0x10d0 drivers/base/core.c:4615
 hci_conn_del_sysfs+0x81/0x180 net/bluetooth/hci_sysfs.c:75
 hci_conn_cleanup net/bluetooth/hci_conn.c:173 [inline]
 hci_conn_del+0x657/0x1180 net/bluetooth/hci_conn.c:1210
 hci_abort_conn_sync+0x76a/0xb20 net/bluetooth/hci_sync.c:5698
 abort_conn_sync+0x197/0x360 net/bluetooth/hci_conn.c:2927
 hci_cmd_sync_work+0x1ab/0x430 net/bluetooth/hci_sync.c:332
 process_one_work+0x9cf/0x1b70 kernel/workqueue.c:3263
 process_scheduled_works kernel/workqueue.c:3346 [inline]
 worker_thread+0x6c8/0xf10 kernel/workqueue.c:3427
 kthread+0x3c5/0x780 kernel/kthread.c:463
 ret_from_fork+0x675/0x7d0 arch/x86/kernel/process.c:158
 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:245
 </TASK>