------------[ 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/u9:2/20809
Modules linked in:
CPU: 1 UID: 0 PID: 20809 Comm: kworker/u9:2 Not tainted syzkaller #0 PREEMPT(full) 
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 10/25/2025
Workqueue: hci6 hci_cmd_sync_work
RIP: 0010:refcount_warn_saturate+0xb2/0x110 lib/refcount.c:28
Code: 94 68 fd 0a 67 48 0f b9 3a eb 4a e8 68 a0 32 fd 48 8d 3d 91 68 fd 0a 67 48 0f b9 3a eb 37 e8 55 a0 32 fd 48 8d 3d 8e 68 fd 0a <67> 48 0f b9 3a eb 24 e8 42 a0 32 fd 48 8d 3d 8b 68 fd 0a 67 48 0f
RSP: 0018:ffffc90003ea7618 EFLAGS: 00010293
RAX: ffffffff848f11fb RBX: 0000000000000003 RCX: ffff888057355b80
RDX: 0000000000000000 RSI: ffffffff8e68e140 RDI: ffffffff8f8c7a90
RBP: 0000000000000000 R08: ffff888057355b80 R09: 0000000000000005
R10: 0000000000000004 R11: 0000000000000000 R12: ffff88807e44f000
R13: ffff8880581f5460 R14: ffff8880581f5478 R15: dffffc0000000000
FS:  0000000000000000(0000) GS:ffff888125f35000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007fc29f048f98 CR3: 00000000ab258000 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+0x599/0xb30 arch/x86/kernel/process.c:158
 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:246
 </TASK>
----------------
Code disassembly (best guess):
   0:	94                   	xchg   %eax,%esp
   1:	68 fd 0a 67 48       	push   $0x48670afd
   6:	0f b9 3a             	ud1    (%rdx),%edi
   9:	eb 4a                	jmp    0x55
   b:	e8 68 a0 32 fd       	call   0xfd32a078
  10:	48 8d 3d 91 68 fd 0a 	lea    0xafd6891(%rip),%rdi        # 0xafd68a8
  17:	67 48 0f b9 3a       	ud1    (%edx),%rdi
  1c:	eb 37                	jmp    0x55
  1e:	e8 55 a0 32 fd       	call   0xfd32a078
  23:	48 8d 3d 8e 68 fd 0a 	lea    0xafd688e(%rip),%rdi        # 0xafd68b8
* 2a:	67 48 0f b9 3a       	ud1    (%edx),%rdi <-- trapping instruction
  2f:	eb 24                	jmp    0x55
  31:	e8 42 a0 32 fd       	call   0xfd32a078
  36:	48 8d 3d 8b 68 fd 0a 	lea    0xafd688b(%rip),%rdi        # 0xafd68c8
  3d:	67                   	addr32
  3e:	48                   	rex.W
  3f:	0f                   	.byte 0xf