syzbot

======================================================
WARNING: possible circular locking dependency detected
5.15.124-syzkaller #0 Not tainted
------------------------------------------------------
kworker/1:4/32123 is trying to acquire lock:
ffff888075328120 (sk_lock-AF_BLUETOOTH-BTPROTO_SCO){+.+.}-{0:0}, at: lock_sock include/net/sock.h:1661 [inline]
ffff888075328120 (sk_lock-AF_BLUETOOTH-BTPROTO_SCO){+.+.}-{0:0}, at: sco_sock_timeout+0xbd/0x230 net/bluetooth/sco.c:96

but task is already holding lock:
ffffc9000524fd20 ((work_completion)(&(&conn->timeout_work)->work)){+.+.}-{0:0}, at: process_one_work+0x7d0/0x10c0 kernel/workqueue.c:2285

which lock already depends on the new lock.


the existing dependency chain (in reverse order) is:

-> #3 ((work_completion)(&(&conn->timeout_work)->work)){+.+.}-{0:0}:
       lock_acquire+0x1db/0x4f0 kernel/locking/lockdep.c:5622
       __flush_work+0xeb/0x1a0 kernel/workqueue.c:3090
       __cancel_work_timer+0x519/0x6a0 kernel/workqueue.c:3181
       sco_conn_del+0x205/0x300 net/bluetooth/sco.c:204
       hci_disconn_cfm include/net/bluetooth/hci_core.h:1521 [inline]
       hci_conn_hash_flush+0x10d/0x210 net/bluetooth/hci_conn.c:1610
       hci_dev_do_close+0x9f6/0x1000 net/bluetooth/hci_core.c:1795
       hci_unregister_dev+0x2a7/0x510 net/bluetooth/hci_core.c:4033
       vhci_release+0x73/0xc0 drivers/bluetooth/hci_vhci.c:342
       __fput+0x3bf/0x890 fs/file_table.c:280
       task_work_run+0x129/0x1a0 kernel/task_work.c:164
       exit_task_work include/linux/task_work.h:32 [inline]
       do_exit+0x6a3/0x2480 kernel/exit.c:872
       do_group_exit+0x144/0x310 kernel/exit.c:994
       get_signal+0xc66/0x14e0 kernel/signal.c:2889
       arch_do_signal_or_restart+0xc3/0x1890 arch/x86/kernel/signal.c:865
       handle_signal_work kernel/entry/common.c:148 [inline]
       exit_to_user_mode_loop+0x97/0x130 kernel/entry/common.c:172
       exit_to_user_mode_prepare+0xb1/0x140 kernel/entry/common.c:208
       __syscall_exit_to_user_mode_work kernel/entry/common.c:290 [inline]
       syscall_exit_to_user_mode+0x5d/0x250 kernel/entry/common.c:301
       do_syscall_64+0x49/0xb0 arch/x86/entry/common.c:86
       entry_SYSCALL_64_after_hwframe+0x61/0xcb

-> #2 (hci_cb_list_lock){+.+.}-{3:3}:
       lock_acquire+0x1db/0x4f0 kernel/locking/lockdep.c:5622
       __mutex_lock_common+0x1da/0x25a0 kernel/locking/mutex.c:596
       __mutex_lock kernel/locking/mutex.c:729 [inline]
       mutex_lock_nested+0x17/0x20 kernel/locking/mutex.c:743
       hci_connect_cfm include/net/bluetooth/hci_core.h:1503 [inline]
       hci_remote_features_evt+0x6d1/0xb50 net/bluetooth/hci_event.c:3323
       hci_event_packet+0x6da/0x1480 net/bluetooth/hci_event.c:6376
       hci_rx_work+0x240/0x7d0 net/bluetooth/hci_core.c:5153
       process_one_work+0x8a1/0x10c0 kernel/workqueue.c:2310
       worker_thread+0xaca/0x1280 kernel/workqueue.c:2457
       kthread+0x3f6/0x4f0 kernel/kthread.c:319
       ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:298

-> #1 (&hdev->lock){+.+.}-{3:3}:
       lock_acquire+0x1db/0x4f0 kernel/locking/lockdep.c:5622
       __mutex_lock_common+0x1da/0x25a0 kernel/locking/mutex.c:596
       __mutex_lock kernel/locking/mutex.c:729 [inline]
       mutex_lock_nested+0x17/0x20 kernel/locking/mutex.c:743
       sco_sock_connect+0x181/0x8c0 net/bluetooth/sco.c:587
       __sys_connect_file net/socket.c:1899 [inline]
       __sys_connect+0x38b/0x410 net/socket.c:1916
       __do_sys_connect net/socket.c:1926 [inline]
       __se_sys_connect net/socket.c:1923 [inline]
       __x64_sys_connect+0x76/0x80 net/socket.c:1923
       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+0x61/0xcb

-> #0 (sk_lock-AF_BLUETOOTH-BTPROTO_SCO){+.+.}-{0:0}:
       check_prev_add kernel/locking/lockdep.c:3053 [inline]
       check_prevs_add kernel/locking/lockdep.c:3172 [inline]
       validate_chain+0x1646/0x58b0 kernel/locking/lockdep.c:3787
       __lock_acquire+0x1295/0x1ff0 kernel/locking/lockdep.c:5011
       lock_acquire+0x1db/0x4f0 kernel/locking/lockdep.c:5622
       lock_sock_nested+0x44/0x100 net/core/sock.c:3227
       lock_sock include/net/sock.h:1661 [inline]
       sco_sock_timeout+0xbd/0x230 net/bluetooth/sco.c:96
       process_one_work+0x8a1/0x10c0 kernel/workqueue.c:2310
       worker_thread+0xaca/0x1280 kernel/workqueue.c:2457
       kthread+0x3f6/0x4f0 kernel/kthread.c:319
       ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:298

other info that might help us debug this:

Chain exists of:
  sk_lock-AF_BLUETOOTH-BTPROTO_SCO --> hci_cb_list_lock --> (work_completion)(&(&conn->timeout_work)->work)

 Possible unsafe locking scenario:

       CPU0                    CPU1
       ----                    ----
  lock((work_completion)(&(&conn->timeout_work)->work));
                               lock(hci_cb_list_lock);
                               lock((work_completion)(&(&conn->timeout_work)->work));
  lock(sk_lock-AF_BLUETOOTH-BTPROTO_SCO);

 *** DEADLOCK ***

2 locks held by kworker/1:4/32123:
 #0: ffff888011c64d38 ((wq_completion)events){+.+.}-{0:0}, at: process_one_work+0x78a/0x10c0 kernel/workqueue.c:2283
 #1: ffffc9000524fd20 ((work_completion)(&(&conn->timeout_work)->work)){+.+.}-{0:0}, at: process_one_work+0x7d0/0x10c0 kernel/workqueue.c:2285

stack backtrace:
CPU: 1 PID: 32123 Comm: kworker/1:4 Not tainted 5.15.124-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 07/12/2023
Workqueue: events sco_sock_timeout
Call Trace:
 <TASK>
 __dump_stack lib/dump_stack.c:88 [inline]
 dump_stack_lvl+0x1e3/0x2cb lib/dump_stack.c:106
 check_noncircular+0x2f8/0x3b0 kernel/locking/lockdep.c:2133
 check_prev_add kernel/locking/lockdep.c:3053 [inline]
 check_prevs_add kernel/locking/lockdep.c:3172 [inline]
 validate_chain+0x1646/0x58b0 kernel/locking/lockdep.c:3787
 __lock_acquire+0x1295/0x1ff0 kernel/locking/lockdep.c:5011
 lock_acquire+0x1db/0x4f0 kernel/locking/lockdep.c:5622
 lock_sock_nested+0x44/0x100 net/core/sock.c:3227
 lock_sock include/net/sock.h:1661 [inline]
 sco_sock_timeout+0xbd/0x230 net/bluetooth/sco.c:96
 process_one_work+0x8a1/0x10c0 kernel/workqueue.c:2310
 worker_thread+0xaca/0x1280 kernel/workqueue.c:2457
 kthread+0x3f6/0x4f0 kernel/kthread.c:319
 ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:298
 </TASK>