------------[ cut here ]------------
refcount_t: underflow; use-after-free.
WARNING: CPU: 0 PID: 5840 at lib/refcount.c:28 refcount_warn_saturate+0x11a/0x1d0 lib/refcount.c:28
Modules linked in:
CPU: 0 UID: 0 PID: 5840 Comm: syz-executor Not tainted syzkaller #0 PREEMPT(full) 
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 10/02/2025
RIP: 0010:refcount_warn_saturate+0x11a/0x1d0 lib/refcount.c:28
Code: 40 58 be 8b e8 c7 a5 f9 fc 90 0f 0b 90 90 eb d7 e8 bb 8b 36 fd c6 05 9b 7f dd 0a 01 90 48 c7 c7 a0 58 be 8b e8 a7 a5 f9 fc 90 <0f> 0b 90 90 eb b7 e8 9b 8b 36 fd c6 05 78 7f dd 0a 01 90 48 c7 c7
RSP: 0018:ffffc90003f6f578 EFLAGS: 00010246
RAX: e8111fe7f13ce600 RBX: 0000000000000003 RCX: ffff8880317f1e40
RDX: 0000000000000000 RSI: 0000000000000000 RDI: 0000000000000002
RBP: 0000000000000000 R08: ffffc90003f6f2a7 R09: 1ffff920007ede54
R10: dffffc0000000000 R11: fffff520007ede55 R12: ffff888073baa000
R13: ffff888058002460 R14: ffff888058002478 R15: dffffc0000000000
FS:  0000000000000000(0000) GS:ffff88812613b000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00002000000012c0 CR3: 00000000742da000 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+0x193/0x700 drivers/base/core.c:4615
 hci_conn_del_sysfs+0xb8/0x170 net/bluetooth/hci_sysfs.c:75
 hci_conn_cleanup net/bluetooth/hci_conn.c:173 [inline]
 hci_conn_del+0xc33/0x11b0 net/bluetooth/hci_conn.c:1217
 hci_conn_hash_flush+0x191/0x230 net/bluetooth/hci_conn.c:2610
 hci_dev_close_sync+0xaef/0x1330 net/bluetooth/hci_sync.c:5308
 hci_dev_do_close net/bluetooth/hci_core.c:501 [inline]
 hci_unregister_dev+0x21a/0x510 net/bluetooth/hci_core.c:2715
 vhci_release+0x152/0x1a0 drivers/bluetooth/hci_vhci.c:690
 __fput+0x44c/0xa70 fs/file_table.c:468
 task_work_run+0x1d4/0x260 kernel/task_work.c:227
 exit_task_work include/linux/task_work.h:40 [inline]
 do_exit+0x6b5/0x2300 kernel/exit.c:966
 do_group_exit+0x21c/0x2d0 kernel/exit.c:1107
 get_signal+0x1285/0x1340 kernel/signal.c:3034
 arch_do_signal_or_restart+0xa0/0x790 arch/x86/kernel/signal.c:337
 exit_to_user_mode_loop+0x72/0x130 kernel/entry/common.c:40
 exit_to_user_mode_prepare include/linux/irq-entry-common.h:225 [inline]
 syscall_exit_to_user_mode_work include/linux/entry-common.h:175 [inline]
 syscall_exit_to_user_mode include/linux/entry-common.h:210 [inline]
 do_syscall_64+0x2bd/0xfa0 arch/x86/entry/syscall_64.c:100
 entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7f8c201c1f85
Code: Unable to access opcode bytes at 0x7f8c201c1f5b.
RSP: 002b:00007ffd30f4bbf0 EFLAGS: 00000293 ORIG_RAX: 00000000000000e6
RAX: 0000000000000000 RBX: 000000000000063c RCX: 00007f8c201c1f85
RDX: 00007ffd30f4bc30 RSI: 0000000000000000 RDI: 0000000000000000
RBP: 00007ffd30f4bc9c R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000293 R12: 0000000000001388
R13: 00000000000927c0 R14: 00000000000641df R15: 00007ffd30f4bcf0
 </TASK>