------------[ cut here ]------------
refcount_t: underflow; use-after-free.
WARNING: lib/refcount.c:28 at refcount_warn_saturate+0xb2/0x110 lib/refcount.c:28, CPU#1: kworker/u9:0/52
Modules linked in:
CPU: 1 UID: 0 PID: 52 Comm: kworker/u9:0 Not tainted syzkaller #0 PREEMPT(full) 
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 10/25/2025
Workqueue: hci3 hci_cmd_sync_work
RIP: 0010:refcount_warn_saturate+0xb2/0x110 lib/refcount.c:28
Code: d4 91 fe 0a 67 48 0f b9 3a eb 4a e8 c8 0c 33 fd 48 8d 3d d1 91 fe 0a 67 48 0f b9 3a eb 37 e8 b5 0c 33 fd 48 8d 3d ce 91 fe 0a <67> 48 0f b9 3a eb 24 e8 a2 0c 33 fd 48 8d 3d cb 91 fe 0a 67 48 0f
RSP: 0018:ffffc90000bd7658 EFLAGS: 00010293
RAX: ffffffff848deb0b RBX: 0000000000000003 RCX: ffff888020ea0000
RDX: 0000000000000000 RSI: ffffffff8e68e200 RDI: ffffffff8f8c7ce0
RBP: 0000000000000000 R08: ffff888020ea0000 R09: 0000000000000005
R10: 0000000000000004 R11: 0000000000000000 R12: ffff88801136b400
R13: ffff88803372f460 R14: ffff88803372f478 R15: dffffc0000000000
FS:  0000000000000000(0000) GS:ffff888125f1f000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 000000110c38ba18 CR3: 000000007686c000 CR4: 00000000003526f0
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+0x3c7/0x3d0 lib/klist.c:206
 klist_put lib/klist.c:217 [inline]
 klist_del lib/klist.c:230 [inline]
 klist_remove+0x1bd/0x340 lib/klist.c:249
 device_move+0x193/0x730 drivers/base/core.c:4615
 hci_conn_del_sysfs+0xb8/0x1a0 net/bluetooth/hci_sysfs.c:75
 hci_conn_cleanup net/bluetooth/hci_conn.c:173 [inline]
 hci_conn_del+0xc36/0x1240 net/bluetooth/hci_conn.c:1234
 hci_abort_conn_sync+0x658/0xe30 net/bluetooth/hci_sync.c:5721
 hci_cmd_sync_work+0x213/0x400 net/bluetooth/hci_sync.c:332
 process_one_work kernel/workqueue.c:3257 [inline]
 process_scheduled_works+0xad1/0x1770 kernel/workqueue.c:3340
 worker_thread+0x8a0/0xda0 kernel/workqueue.c:3421
 kthread+0x711/0x8a0 kernel/kthread.c:463
 ret_from_fork+0x510/0xa50 arch/x86/kernel/process.c:158
 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:246
 </TASK>
----------------
Code disassembly (best guess), 1 bytes skipped:
   0:	91                   	xchg   %eax,%ecx
   1:	fe 0a                	decb   (%rdx)
   3:	67 48 0f b9 3a       	ud1    (%edx),%rdi
   8:	eb 4a                	jmp    0x54
   a:	e8 c8 0c 33 fd       	call   0xfd330cd7
   f:	48 8d 3d d1 91 fe 0a 	lea    0xafe91d1(%rip),%rdi        # 0xafe91e7
  16:	67 48 0f b9 3a       	ud1    (%edx),%rdi
  1b:	eb 37                	jmp    0x54
  1d:	e8 b5 0c 33 fd       	call   0xfd330cd7
  22:	48 8d 3d ce 91 fe 0a 	lea    0xafe91ce(%rip),%rdi        # 0xafe91f7
* 29:	67 48 0f b9 3a       	ud1    (%edx),%rdi <-- trapping instruction
  2e:	eb 24                	jmp    0x54
  30:	e8 a2 0c 33 fd       	call   0xfd330cd7
  35:	48 8d 3d cb 91 fe 0a 	lea    0xafe91cb(%rip),%rdi        # 0xafe9207
  3c:	67                   	addr32
  3d:	48                   	rex.W
  3e:	0f                   	.byte 0xf