------------[ cut here ]------------
refcount_t: underflow; use-after-free.
WARNING: CPU: 1 PID: 5872 at lib/refcount.c:28 refcount_warn_saturate+0x11a/0x1d0 lib/refcount.c:28
Modules linked in:
CPU: 1 UID: 0 PID: 5872 Comm: syz-executor Not tainted syzkaller #0 PREEMPT(full) 
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 08/18/2025
RIP: 0010:refcount_warn_saturate+0x11a/0x1d0 lib/refcount.c:28
Code: a0 ba e2 8b e8 37 c2 ba fc 90 0f 0b 90 90 eb d7 e8 8b 26 f7 fc c6 05 d5 11 c5 0a 01 90 48 c7 c7 00 bb e2 8b e8 17 c2 ba fc 90 <0f> 0b 90 90 eb b7 e8 6b 26 f7 fc c6 05 b2 11 c5 0a 01 90 48 c7 c7
RSP: 0018:ffffc900040ef7b8 EFLAGS: 00010246
RAX: f8815792a891a200 RBX: 0000000000000003 RCX: ffff888027445a00
RDX: 0000000000000000 RSI: 0000000000000000 RDI: 0000000000000002
RBP: 0000000000000000 R08: 0000000000000003 R09: 0000000000000004
R10: dffffc0000000000 R11: fffffbfff1bfa22c R12: ffff888031304800
R13: ffff888028703460 R14: ffff888028703478 R15: dffffc0000000000
FS:  0000000000000000(0000) GS:ffff888125d12000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007fbbd9160f98 CR3: 00000000783b8000 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:1211
 hci_conn_hash_flush+0x191/0x230 net/bluetooth/hci_conn.c:2600
 hci_dev_close_sync+0xaef/0x1330 net/bluetooth/hci_sync.c:5301
 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+0x1d1/0x260 kernel/task_work.c:227
 exit_task_work include/linux/task_work.h:40 [inline]
 do_exit+0x6b5/0x2300 kernel/exit.c:961
 do_group_exit+0x21c/0x2d0 kernel/exit.c:1102
 __do_sys_exit_group kernel/exit.c:1113 [inline]
 __se_sys_exit_group kernel/exit.c:1111 [inline]
 __x64_sys_exit_group+0x3f/0x40 kernel/exit.c:1111
 x64_sys_call+0x21f7/0x2200 arch/x86/include/generated/asm/syscalls_64.h:232
 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
 do_syscall_64+0xfa/0x3b0 arch/x86/entry/syscall_64.c:94
 entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7f01ff18eec9
Code: Unable to access opcode bytes at 0x7f01ff18ee9f.
RSP: 002b:00007ffeff43c3f8 EFLAGS: 00000246 ORIG_RAX: 00000000000000e7
RAX: ffffffffffffffda RBX: 0000000000000007 RCX: 00007f01ff18eec9
RDX: 00007f01ff185613 RSI: 0000000000000000 RDI: 0000000000000007
RBP: 0000000000000001 R08: 0000000000000001 R09: 0000000000000007
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 00000000000927c0 R14: 00000000000363a7 R15: 00007ffeff43d130
 </TASK>