R10: 0000000020000200 R11: 0000000000000202 R12: 0000000020000300
R13: 0000000020ff9000 R14: 0000000020000200 R15: 0000000020ffb000
 </TASK>
======================================================
WARNING: possible circular locking dependency detected
6.2.0-next-20230224 #1 Not tainted
------------------------------------------------------
syz-executor.1/5810 is trying to acquire lock:
ffff888018304880 ((work_completion)(&hdev->cmd_sync_work)){+.+.}-{0:0}, at: __flush_work+0xdd/0xd80

but task is already holding lock:
ffff888018304920 (&hdev->cmd_sync_work_lock){+.+.}-{3:3}, at: hci_cmd_sync_clear+0x45/0x250

which lock already depends on the new lock.


the existing dependency chain (in reverse order) is:

-> #1 (&hdev->cmd_sync_work_lock){+.+.}-{3:3}:
       __mutex_lock+0x133/0x14a0
       hci_cmd_sync_work+0x1e6/0x320
       process_one_work+0xa0f/0x1790
       worker_thread+0x63b/0x1260
       kthread+0x2e9/0x3a0
       ret_from_fork+0x2c/0x50

-> #0 ((work_completion)(&hdev->cmd_sync_work)){+.+.}-{0:0}:
       __lock_acquire+0x2d56/0x6380
       lock_acquire.part.0+0xea/0x320
       __flush_work+0x109/0xd80
       __cancel_work_timer+0x39c/0x4e0
       hci_cmd_sync_clear+0x52/0x250
       hci_unregister_dev+0xf9/0x410
       vhci_release+0x80/0x100
       __fput+0x263/0xa40
       task_work_run+0x174/0x280
       do_exit+0xad8/0x2800
       do_group_exit+0xd4/0x2a0
       get_signal+0x23c8/0x2450
       arch_do_signal_or_restart+0x79/0x590
       exit_to_user_mode_prepare+0x122/0x190
       syscall_exit_to_user_mode+0x1d/0x50
       do_syscall_64+0x4c/0x90
       entry_SYSCALL_64_after_hwframe+0x72/0xdc

other info that might help us debug this:

 Possible unsafe locking scenario:

       CPU0                    CPU1
       ----                    ----
  lock(&hdev->cmd_sync_work_lock);
                               lock((work_completion)(&hdev->cmd_sync_work));
                               lock(&hdev->cmd_sync_work_lock);
  lock((work_completion)(&hdev->cmd_sync_work));

 *** DEADLOCK ***

1 lock held by syz-executor.1/5810:
 #0: ffff888018304920 (&hdev->cmd_sync_work_lock){+.+.}-{3:3}, at: hci_cmd_sync_clear+0x45/0x250

stack backtrace:
CPU: 0 PID: 5810 Comm: syz-executor.1 Not tainted 6.2.0-next-20230224 #1
Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS 1.12.0-1 04/01/2014
Call Trace:
 <TASK>
 dump_stack_lvl+0x91/0xf0
 check_noncircular+0x263/0x2e0
 __lock_acquire+0x2d56/0x6380
 lock_acquire.part.0+0xea/0x320
 __flush_work+0x109/0xd80
 __cancel_work_timer+0x39c/0x4e0
 hci_cmd_sync_clear+0x52/0x250
 hci_unregister_dev+0xf9/0x410
 vhci_release+0x80/0x100
 __fput+0x263/0xa40
 task_work_run+0x174/0x280
 do_exit+0xad8/0x2800
 do_group_exit+0xd4/0x2a0
 get_signal+0x23c8/0x2450
 arch_do_signal_or_restart+0x79/0x590
 exit_to_user_mode_prepare+0x122/0x190
 syscall_exit_to_user_mode+0x1d/0x50
 do_syscall_64+0x4c/0x90
 entry_SYSCALL_64_after_hwframe+0x72/0xdc
RIP: 0033:0x7f8d66a93b19
Code: Unable to access opcode bytes at 0x7f8d66a93aef.
RSP: 002b:00007f8d64009218 EFLAGS: 00000246 ORIG_RAX: 00000000000000ca
RAX: fffffffffffffe00 RBX: 00007f8d66ba6f68 RCX: 00007f8d66a93b19
RDX: 0000000000000000 RSI: 0000000000000080 RDI: 00007f8d66ba6f68
RBP: 00007f8d66ba6f60 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 00007f8d66ba6f6c
R13: 00007ffd33c26a5f R14: 00007f8d64009300 R15: 0000000000022000
 </TASK>
Bluetooth: hci6: unexpected cc 0x0c03 length: 249 > 1
Bluetooth: hci6: unexpected cc 0x1003 length: 249 > 9
Bluetooth: hci6: unexpected cc 0x1001 length: 249 > 9
Bluetooth: hci6: unexpected cc 0x0c23 length: 249 > 4
Bluetooth: hci6: unexpected cc 0x0c25 length: 249 > 3
Bluetooth: hci6: unexpected cc 0x0c38 length: 249 > 2
Bluetooth: hci6: command 0x0409 tx timeout
Bluetooth: hci6: command 0x041b tx timeout
Bluetooth: hci6: command 0x040f tx timeout