======================================================
WARNING: possible circular locking dependency detected
6.1.41-syzkaller #0 Not tainted
------------------------------------------------------
syz-executor.3/14265 is trying to acquire lock:
ffff8880792f6c70 ((work_completion)(&(&conn->timeout_work)->work)){+.+.}-{0:0}, at: __flush_work+0xcf/0x1a0 kernel/workqueue.c:3072

but task is already holding lock:
ffffffff8e1efca8 (hci_cb_list_lock){+.+.}-{3:3}, at: hci_disconn_cfm include/net/bluetooth/hci_core.h:1791 [inline]
ffffffff8e1efca8 (hci_cb_list_lock){+.+.}-{3:3}, at: hci_conn_hash_flush+0xb8/0x280 net/bluetooth/hci_conn.c:2488

which lock already depends on the new lock.


the existing dependency chain (in reverse order) is:

-> #3 (hci_cb_list_lock){+.+.}-{3:3}:
       lock_acquire+0x1f8/0x5a0 kernel/locking/lockdep.c:5669
       __mutex_lock_common+0x1d4/0x2520 kernel/locking/mutex.c:603
       __mutex_lock kernel/locking/mutex.c:747 [inline]
       mutex_lock_nested+0x17/0x20 kernel/locking/mutex.c:799
       hci_connect_cfm include/net/bluetooth/hci_core.h:1776 [inline]
       hci_remote_features_evt+0x671/0xaa0 net/bluetooth/hci_event.c:3753
       hci_event_func net/bluetooth/hci_event.c:7471 [inline]
       hci_event_packet+0x96c/0x1360 net/bluetooth/hci_event.c:7523
       hci_rx_work+0x40d/0xa80 net/bluetooth/hci_core.c:4060
       process_one_work+0x8aa/0x11f0 kernel/workqueue.c:2292
       worker_thread+0xa5f/0x1210 kernel/workqueue.c:2439
       kthread+0x26e/0x300 kernel/kthread.c:376
       ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:306

-> #2 (&hdev->lock){+.+.}-{3:3}:
       lock_acquire+0x1f8/0x5a0 kernel/locking/lockdep.c:5669
       __mutex_lock_common+0x1d4/0x2520 kernel/locking/mutex.c:603
       __mutex_lock kernel/locking/mutex.c:747 [inline]
       mutex_lock_nested+0x17/0x20 kernel/locking/mutex.c:799
       sco_sock_connect+0x181/0x8d0 net/bluetooth/sco.c:593
       __sys_connect_file net/socket.c:1976 [inline]
       __sys_connect+0x2c9/0x300 net/socket.c:1993
       __do_sys_connect net/socket.c:2003 [inline]
       __se_sys_connect net/socket.c:2000 [inline]
       __x64_sys_connect+0x76/0x80 net/socket.c:2000
       do_syscall_x64 arch/x86/entry/common.c:50 [inline]
       do_syscall_64+0x3d/0xb0 arch/x86/entry/common.c:80
       entry_SYSCALL_64_after_hwframe+0x63/0xcd

-> #1 (sk_lock-AF_BLUETOOTH-BTPROTO_SCO){+.+.}-{0:0}:
       lock_acquire+0x1f8/0x5a0 kernel/locking/lockdep.c:5669
       lock_sock_nested+0x44/0x100 net/core/sock.c:3463
       lock_sock include/net/sock.h:1733 [inline]
       sco_sock_timeout+0xbd/0x230 net/bluetooth/sco.c:97
       process_one_work+0x8aa/0x11f0 kernel/workqueue.c:2292
       worker_thread+0xa5f/0x1210 kernel/workqueue.c:2439
       kthread+0x26e/0x300 kernel/kthread.c:376
       ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:306

-> #0 ((work_completion)(&(&conn->timeout_work)->work)){+.+.}-{0:0}:
       check_prev_add kernel/locking/lockdep.c:3098 [inline]
       check_prevs_add kernel/locking/lockdep.c:3217 [inline]
       validate_chain+0x1667/0x58e0 kernel/locking/lockdep.c:3832
       __lock_acquire+0x125b/0x1f80 kernel/locking/lockdep.c:5056
       lock_acquire+0x1f8/0x5a0 kernel/locking/lockdep.c:5669
       __flush_work+0xeb/0x1a0 kernel/workqueue.c:3072
       __cancel_work_timer+0x519/0x6a0 kernel/workqueue.c:3163
       sco_conn_del+0x205/0x300 net/bluetooth/sco.c:205
       hci_disconn_cfm include/net/bluetooth/hci_core.h:1794 [inline]
       hci_conn_hash_flush+0x10e/0x280 net/bluetooth/hci_conn.c:2488
       hci_dev_close_sync+0xa2d/0x1000 net/bluetooth/hci_sync.c:4885
       hci_dev_do_close net/bluetooth/hci_core.c:554 [inline]
       hci_unregister_dev+0x1df/0x480 net/bluetooth/hci_core.c:2704
       vhci_release+0x7f/0xd0 drivers/bluetooth/hci_vhci.c:568
       __fput+0x3b7/0x890 fs/file_table.c:320
       task_work_run+0x246/0x300 kernel/task_work.c:179
       exit_task_work include/linux/task_work.h:38 [inline]
       do_exit+0x6fb/0x2300 kernel/exit.c:869
       do_group_exit+0x202/0x2b0 kernel/exit.c:1019
       get_signal+0x16f7/0x17d0 kernel/signal.c:2858
       arch_do_signal_or_restart+0xb0/0x1a10 arch/x86/kernel/signal.c:869
       exit_to_user_mode_loop+0x6a/0x100 kernel/entry/common.c:168
       exit_to_user_mode_prepare+0xb1/0x140 kernel/entry/common.c:204
       __syscall_exit_to_user_mode_work kernel/entry/common.c:286 [inline]
       syscall_exit_to_user_mode+0x60/0x270 kernel/entry/common.c:297
       do_syscall_64+0x49/0xb0 arch/x86/entry/common.c:86
       entry_SYSCALL_64_after_hwframe+0x63/0xcd

other info that might help us debug this:

Chain exists of:
  (work_completion)(&(&conn->timeout_work)->work) --> &hdev->lock --> hci_cb_list_lock

 Possible unsafe locking scenario:

       CPU0                    CPU1
       ----                    ----
  lock(hci_cb_list_lock);
                               lock(&hdev->lock);
                               lock(hci_cb_list_lock);
  lock((work_completion)(&(&conn->timeout_work)->work));

 *** DEADLOCK ***

3 locks held by syz-executor.3/14265:
 #0: ffff888043d050b8 (&hdev->req_lock){+.+.}-{3:3}, at: hci_dev_do_close net/bluetooth/hci_core.c:552 [inline]
 #0: ffff888043d050b8 (&hdev->req_lock){+.+.}-{3:3}, at: hci_unregister_dev+0x1d7/0x480 net/bluetooth/hci_core.c:2704
 #1: ffff888043d04078 (&hdev->lock){+.+.}-{3:3}, at: hci_dev_close_sync+0x445/0x1000 net/bluetooth/hci_sync.c:4872
 #2: ffffffff8e1efca8 (hci_cb_list_lock){+.+.}-{3:3}, at: hci_disconn_cfm include/net/bluetooth/hci_core.h:1791 [inline]
 #2: ffffffff8e1efca8 (hci_cb_list_lock){+.+.}-{3:3}, at: hci_conn_hash_flush+0xb8/0x280 net/bluetooth/hci_conn.c:2488

stack backtrace:
CPU: 0 PID: 14265 Comm: syz-executor.3 Not tainted 6.1.41-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 07/12/2023
Call Trace:
 <TASK>
 __dump_stack lib/dump_stack.c:88 [inline]
 dump_stack_lvl+0x1e3/0x2cb lib/dump_stack.c:106
 check_noncircular+0x2fa/0x3b0 kernel/locking/lockdep.c:2178
 check_prev_add kernel/locking/lockdep.c:3098 [inline]
 check_prevs_add kernel/locking/lockdep.c:3217 [inline]
 validate_chain+0x1667/0x58e0 kernel/locking/lockdep.c:3832
 __lock_acquire+0x125b/0x1f80 kernel/locking/lockdep.c:5056
 lock_acquire+0x1f8/0x5a0 kernel/locking/lockdep.c:5669
 __flush_work+0xeb/0x1a0 kernel/workqueue.c:3072
 __cancel_work_timer+0x519/0x6a0 kernel/workqueue.c:3163
 sco_conn_del+0x205/0x300 net/bluetooth/sco.c:205
 hci_disconn_cfm include/net/bluetooth/hci_core.h:1794 [inline]
 hci_conn_hash_flush+0x10e/0x280 net/bluetooth/hci_conn.c:2488
 hci_dev_close_sync+0xa2d/0x1000 net/bluetooth/hci_sync.c:4885
 hci_dev_do_close net/bluetooth/hci_core.c:554 [inline]
 hci_unregister_dev+0x1df/0x480 net/bluetooth/hci_core.c:2704
 vhci_release+0x7f/0xd0 drivers/bluetooth/hci_vhci.c:568
 __fput+0x3b7/0x890 fs/file_table.c:320
 task_work_run+0x246/0x300 kernel/task_work.c:179
 exit_task_work include/linux/task_work.h:38 [inline]
 do_exit+0x6fb/0x2300 kernel/exit.c:869
 do_group_exit+0x202/0x2b0 kernel/exit.c:1019
 get_signal+0x16f7/0x17d0 kernel/signal.c:2858
 arch_do_signal_or_restart+0xb0/0x1a10 arch/x86/kernel/signal.c:869
 exit_to_user_mode_loop+0x6a/0x100 kernel/entry/common.c:168
 exit_to_user_mode_prepare+0xb1/0x140 kernel/entry/common.c:204
 __syscall_exit_to_user_mode_work kernel/entry/common.c:286 [inline]
 syscall_exit_to_user_mode+0x60/0x270 kernel/entry/common.c:297
 do_syscall_64+0x49/0xb0 arch/x86/entry/common.c:86
 entry_SYSCALL_64_after_hwframe+0x63/0xcd
RIP: 0033:0x7f47cb0a7f35
Code: Unable to access opcode bytes at 0x7f47cb0a7f0b.
RSP: 002b:00007f47cbe02010 EFLAGS: 00000293 ORIG_RAX: 00000000000000e6
RAX: fffffffffffffdfc RBX: 00007f47cb19c050 RCX: 00007f47cb0a7f35
RDX: 00007f47cbe02050 RSI: 0000000000000000 RDI: 0000000000000000
RBP: 00007f47cb0c847a R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000293 R12: 0000000000000000
R13: 000000000000006e R14: 00007f47cb19c050 R15: 00007ffe65161f78
 </TASK>