syzbot

Bluetooth: hci0: hardware error 0x00
======================================================
WARNING: possible circular locking dependency detected
5.15.182-syzkaller #0 Not tainted
------------------------------------------------------
kworker/u5:2/4172 is trying to acquire lock:
ffff888078d34120 (sk_lock-AF_BLUETOOTH-BTPROTO_SCO){+.+.}-{0:0}, at: lock_sock include/net/sock.h:1694 [inline]
ffff888078d34120 (sk_lock-AF_BLUETOOTH-BTPROTO_SCO){+.+.}-{0:0}, at: sco_conn_del+0x142/0x360 net/bluetooth/sco.c:206

but task is already holding lock:
ffffffff8d370e08 (hci_cb_list_lock){+.+.}-{3:3}, at: hci_disconn_cfm include/net/bluetooth/hci_core.h:1517 [inline]
ffffffff8d370e08 (hci_cb_list_lock){+.+.}-{3:3}, at: hci_conn_hash_flush+0xa4/0x220 net/bluetooth/hci_conn.c:1622

which lock already depends on the new lock.


the existing dependency chain (in reverse order) is:

-> #2 (hci_cb_list_lock){+.+.}-{3:3}:
       __mutex_lock_common+0x1eb/0x2390 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:1502 [inline]
       hci_remote_features_evt+0x5cf/0xa10 net/bluetooth/hci_event.c:3352
       hci_event_packet+0x613/0x12f0 net/bluetooth/hci_event.c:6419
       hci_rx_work+0x255/0xa10 net/bluetooth/hci_core.c:5160
       process_one_work+0x863/0x1000 kernel/workqueue.c:2310
       worker_thread+0xaa8/0x12a0 kernel/workqueue.c:2457
       kthread+0x436/0x520 kernel/kthread.c:334
       ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:287

-> #1 (&hdev->lock){+.+.}-{3:3}:
       __mutex_lock_common+0x1eb/0x2390 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+0x18f/0x910 net/bluetooth/sco.c:597
       __sys_connect_file net/socket.c:1923 [inline]
       __sys_connect+0x389/0x410 net/socket.c:1940
       __do_sys_connect net/socket.c:1950 [inline]
       __se_sys_connect net/socket.c:1947 [inline]
       __x64_sys_connect+0x76/0x80 net/socket.c:1947
       do_syscall_x64 arch/x86/entry/common.c:50 [inline]
       do_syscall_64+0x4c/0xa0 arch/x86/entry/common.c:80
       entry_SYSCALL_64_after_hwframe+0x66/0xd0

-> #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 kernel/locking/lockdep.c:3788 [inline]
       __lock_acquire+0x2c33/0x7c60 kernel/locking/lockdep.c:5012
       lock_acquire+0x197/0x3f0 kernel/locking/lockdep.c:5623
       lock_sock_nested+0x44/0x100 net/core/sock.c:3251
       lock_sock include/net/sock.h:1694 [inline]
       sco_conn_del+0x142/0x360 net/bluetooth/sco.c:206
       hci_disconn_cfm include/net/bluetooth/hci_core.h:1520 [inline]
       hci_conn_hash_flush+0x107/0x220 net/bluetooth/hci_conn.c:1622
       hci_dev_do_close+0x991/0x1030 net/bluetooth/hci_core.c:1795
       hci_error_reset+0x101/0x2c0 net/bluetooth/hci_core.c:2341
       process_one_work+0x863/0x1000 kernel/workqueue.c:2310
       worker_thread+0xaa8/0x12a0 kernel/workqueue.c:2457
       kthread+0x436/0x520 kernel/kthread.c:334
       ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:287

other info that might help us debug this:

Chain exists of:
  sk_lock-AF_BLUETOOTH-BTPROTO_SCO --> &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(sk_lock-AF_BLUETOOTH-BTPROTO_SCO);

 *** DEADLOCK ***

5 locks held by kworker/u5:2/4172:
 #0: ffff888024171938 ((wq_completion)hci0){+.+.}-{0:0}, at: process_one_work+0x760/0x1000 kernel/workqueue.c:-1
 #1: ffffc90002e9fd00 ((work_completion)(&hdev->error_reset)){+.+.}-{0:0}, at: process_one_work+0x7a3/0x1000 kernel/workqueue.c:2285
 #2: ffff88807c9a4ff0 (&hdev->req_lock){+.+.}-{3:3}, at: hci_dev_do_close+0x5f/0x1030 net/bluetooth/hci_core.c:1737
 #3: ffff88807c9a4078 (&hdev->lock){+.+.}-{3:3}, at: hci_dev_do_close+0x3f4/0x1030 net/bluetooth/hci_core.c:1782
 #4: ffffffff8d370e08 (hci_cb_list_lock){+.+.}-{3:3}, at: hci_disconn_cfm include/net/bluetooth/hci_core.h:1517 [inline]
 #4: ffffffff8d370e08 (hci_cb_list_lock){+.+.}-{3:3}, at: hci_conn_hash_flush+0xa4/0x220 net/bluetooth/hci_conn.c:1622

stack backtrace:
CPU: 1 PID: 4172 Comm: kworker/u5:2 Not tainted 5.15.182-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 04/19/2025
Workqueue: hci0 hci_error_reset
Call Trace:
 <TASK>
 dump_stack_lvl+0x168/0x230 lib/dump_stack.c:106
 check_noncircular+0x274/0x310 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 kernel/locking/lockdep.c:3788 [inline]
 __lock_acquire+0x2c33/0x7c60 kernel/locking/lockdep.c:5012
 lock_acquire+0x197/0x3f0 kernel/locking/lockdep.c:5623
 lock_sock_nested+0x44/0x100 net/core/sock.c:3251
 lock_sock include/net/sock.h:1694 [inline]
 sco_conn_del+0x142/0x360 net/bluetooth/sco.c:206
 hci_disconn_cfm include/net/bluetooth/hci_core.h:1520 [inline]
 hci_conn_hash_flush+0x107/0x220 net/bluetooth/hci_conn.c:1622
 hci_dev_do_close+0x991/0x1030 net/bluetooth/hci_core.c:1795
 hci_error_reset+0x101/0x2c0 net/bluetooth/hci_core.c:2341
 process_one_work+0x863/0x1000 kernel/workqueue.c:2310
 worker_thread+0xaa8/0x12a0 kernel/workqueue.c:2457