======================================================
WARNING: possible circular locking dependency detected
6.7.0-rc6-syzkaller-00171-gdcea1bd45e6d #0 Not tainted
------------------------------------------------------
syz-executor.4/18568 is trying to acquire lock:
ffff888046db4ae0 ((work_completion)(&(&hdev->discov_off)->work)){+.+.}-{0:0}, at: __flush_work+0xfa/0xa10 kernel/workqueue.c:3400

but task is already holding lock:
ffff888046db4078 (&hdev->lock){+.+.}-{3:3}, at: hci_unregister_dev+0x46a/0x600 net/bluetooth/hci_core.c:2744

which lock already depends on the new lock.


the existing dependency chain (in reverse order) is:

-> #1 (&hdev->lock){+.+.}-{3:3}:
       __mutex_lock_common kernel/locking/mutex.c:603 [inline]
       __mutex_lock+0x175/0x9d0 kernel/locking/mutex.c:747
       discov_off+0x8c/0x1d0 net/bluetooth/mgmt.c:1055
       process_one_work+0x886/0x15d0 kernel/workqueue.c:2627
       process_scheduled_works kernel/workqueue.c:2700 [inline]
       worker_thread+0x8b9/0x1290 kernel/workqueue.c:2781
       kthread+0x2c6/0x3a0 kernel/kthread.c:388
       ret_from_fork+0x45/0x80 arch/x86/kernel/process.c:147
       ret_from_fork_asm+0x11/0x20 arch/x86/entry/entry_64.S:242

-> #0 ((work_completion)(&(&hdev->discov_off)->work)){+.+.}-{0:0}:
       check_prev_add kernel/locking/lockdep.c:3134 [inline]
       check_prevs_add kernel/locking/lockdep.c:3253 [inline]
       validate_chain kernel/locking/lockdep.c:3869 [inline]
       __lock_acquire+0x2433/0x3b20 kernel/locking/lockdep.c:5137
       lock_acquire kernel/locking/lockdep.c:5754 [inline]
       lock_acquire+0x1ae/0x520 kernel/locking/lockdep.c:5719
       __flush_work+0x103/0xa10 kernel/workqueue.c:3400
       __cancel_work_timer+0x3ef/0x590 kernel/workqueue.c:3491
       mgmt_index_removed+0x1ed/0x350 net/bluetooth/mgmt.c:9447
       hci_unregister_dev+0x472/0x600 net/bluetooth/hci_core.c:2745
       vhci_release+0x7f/0x100 drivers/bluetooth/hci_vhci.c:674
       __fput+0x270/0xb70 fs/file_table.c:394
       task_work_run+0x14d/0x240 kernel/task_work.c:180
       exit_task_work include/linux/task_work.h:38 [inline]
       do_exit+0xa8a/0x2ad0 kernel/exit.c:869
       do_group_exit+0xd4/0x2a0 kernel/exit.c:1018
       get_signal+0x23b5/0x2790 kernel/signal.c:2904
       arch_do_signal_or_restart+0x90/0x7f0 arch/x86/kernel/signal.c:309
       exit_to_user_mode_loop kernel/entry/common.c:168 [inline]
       exit_to_user_mode_prepare+0x121/0x240 kernel/entry/common.c:204
       __syscall_exit_to_user_mode_work kernel/entry/common.c:285 [inline]
       syscall_exit_to_user_mode+0x1e/0x60 kernel/entry/common.c:296
       do_syscall_64+0x4d/0x110 arch/x86/entry/common.c:89
       entry_SYSCALL_64_after_hwframe+0x63/0x6b

other info that might help us debug this:

 Possible unsafe locking scenario:

       CPU0                    CPU1
       ----                    ----
  lock(&hdev->lock);
                               lock((work_completion)(&(&hdev->discov_off)->work));
                               lock(&hdev->lock);
  lock((work_completion)(&(&hdev->discov_off)->work));

 *** DEADLOCK ***

1 lock held by syz-executor.4/18568:
 #0: ffff888046db4078 (&hdev->lock){+.+.}-{3:3}, at: hci_unregister_dev+0x46a/0x600 net/bluetooth/hci_core.c:2744

stack backtrace:
CPU: 0 PID: 18568 Comm: syz-executor.4 Not tainted 6.7.0-rc6-syzkaller-00171-gdcea1bd45e6d #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 11/17/2023
Call Trace:
 <TASK>
 __dump_stack lib/dump_stack.c:88 [inline]
 dump_stack_lvl+0xd9/0x1b0 lib/dump_stack.c:106
 check_noncircular+0x317/0x400 kernel/locking/lockdep.c:2187
 check_prev_add kernel/locking/lockdep.c:3134 [inline]
 check_prevs_add kernel/locking/lockdep.c:3253 [inline]
 validate_chain kernel/locking/lockdep.c:3869 [inline]
 __lock_acquire+0x2433/0x3b20 kernel/locking/lockdep.c:5137
 lock_acquire kernel/locking/lockdep.c:5754 [inline]
 lock_acquire+0x1ae/0x520 kernel/locking/lockdep.c:5719
 __flush_work+0x103/0xa10 kernel/workqueue.c:3400
 __cancel_work_timer+0x3ef/0x590 kernel/workqueue.c:3491
 mgmt_index_removed+0x1ed/0x350 net/bluetooth/mgmt.c:9447
 hci_unregister_dev+0x472/0x600 net/bluetooth/hci_core.c:2745
 vhci_release+0x7f/0x100 drivers/bluetooth/hci_vhci.c:674
 __fput+0x270/0xb70 fs/file_table.c:394
 task_work_run+0x14d/0x240 kernel/task_work.c:180
 exit_task_work include/linux/task_work.h:38 [inline]
 do_exit+0xa8a/0x2ad0 kernel/exit.c:869
 do_group_exit+0xd4/0x2a0 kernel/exit.c:1018
 get_signal+0x23b5/0x2790 kernel/signal.c:2904
 arch_do_signal_or_restart+0x90/0x7f0 arch/x86/kernel/signal.c:309
 exit_to_user_mode_loop kernel/entry/common.c:168 [inline]
 exit_to_user_mode_prepare+0x121/0x240 kernel/entry/common.c:204
 __syscall_exit_to_user_mode_work kernel/entry/common.c:285 [inline]
 syscall_exit_to_user_mode+0x1e/0x60 kernel/entry/common.c:296
 do_syscall_64+0x4d/0x110 arch/x86/entry/common.c:89
 entry_SYSCALL_64_after_hwframe+0x63/0x6b
RIP: 0033:0x7f8c3807cce9
Code: Unable to access opcode bytes at 0x7f8c3807ccbf.
RSP: 002b:00007f8c38e620c8 EFLAGS: 00000246 ORIG_RAX: 000000000000012b
RAX: fffffffffffffe00 RBX: 00007f8c3819bf80 RCX: 00007f8c3807cce9
RDX: 000000000000e100 RSI: 00000000200005c0 RDI: 0000000000000007
RBP: 00007f8c380c947a R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 000000000000000b R14: 00007f8c3819bf80 R15: 00007ffd6bcacbf8
 </TASK>
syz_tun (unregistering): left allmulticast mode
syz_tun (unregistering): left promiscuous mode
bridge0: port 1(syz_tun) entered disabled state