====================================================== WARNING: possible circular locking dependency detected syzkaller #0 Not tainted ------------------------------------------------------ kworker/u5:0/146 is trying to acquire lock: ffffffff8d5b37c8 (rfcomm_mutex){+.+.}-{3:3}, at: rfcomm_security_cfm+0x95/0x780 net/bluetooth/rfcomm/core.c:2210 but task is already holding lock: ffffffff8d593e48 (hci_cb_list_lock){+.+.}-{3:3}, at: hci_auth_cfm include/net/bluetooth/hci_core.h:1540 [inline] ffffffff8d593e48 (hci_cb_list_lock){+.+.}-{3:3}, at: hci_auth_complete_evt+0x308/0xbb0 net/bluetooth/hci_event.c:3067 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+0x1e5/0x2400 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:1504 [inline] hci_remote_features_evt+0x5d9/0xa10 net/bluetooth/hci_event.c:3367 hci_event_packet+0x600/0x1310 net/bluetooth/hci_event.c:6455 hci_rx_work+0x255/0xa10 net/bluetooth/hci_core.c:5190 process_one_work+0x867/0xff0 kernel/workqueue.c:2310 worker_thread+0xad7/0x12a0 kernel/workqueue.c:2457 kthread+0x42e/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+0x1e5/0x2400 kernel/locking/mutex.c:596 __mutex_lock kernel/locking/mutex.c:729 [inline] mutex_lock_nested+0x17/0x20 kernel/locking/mutex.c:743 l2cap_chan_connect+0xfb/0xe20 net/bluetooth/l2cap_core.c:8205 l2cap_sock_connect+0x5a3/0x770 net/bluetooth/l2cap_sock.c:255 kernel_connect+0x11c/0x180 net/socket.c:3498 rfcomm_session_create net/bluetooth/rfcomm/core.c:807 [inline] __rfcomm_dlc_open net/bluetooth/rfcomm/core.c:384 [inline] rfcomm_dlc_open+0x600/0x10c0 net/bluetooth/rfcomm/core.c:427 rfcomm_sock_connect+0x2e9/0x600 net/bluetooth/rfcomm/sock.c:421 __sys_connect_file net/socket.c:1933 [inline] __sys_connect+0x3cb/0x450 net/socket.c:1950 __do_sys_connect net/socket.c:1960 [inline] __se_sys_connect net/socket.c:1957 [inline] __x64_sys_connect+0x76/0x80 net/socket.c:1957 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 (rfcomm_mutex){+.+.}-{3:3}: 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+0x2c66/0x7b50 kernel/locking/lockdep.c:5012 lock_acquire+0x19e/0x400 kernel/locking/lockdep.c:5625 __mutex_lock_common+0x1e5/0x2400 kernel/locking/mutex.c:596 __mutex_lock kernel/locking/mutex.c:729 [inline] mutex_lock_nested+0x17/0x20 kernel/locking/mutex.c:743 rfcomm_security_cfm+0x95/0x780 net/bluetooth/rfcomm/core.c:2210 hci_auth_cfm include/net/bluetooth/hci_core.h:1543 [inline] hci_auth_complete_evt+0x388/0xbb0 net/bluetooth/hci_event.c:3067 hci_event_packet+0x701/0x1310 net/bluetooth/hci_event.c:6439 hci_rx_work+0x255/0xa10 net/bluetooth/hci_core.c:5190 process_one_work+0x867/0xff0 kernel/workqueue.c:2310 worker_thread+0xad7/0x12a0 kernel/workqueue.c:2457 kthread+0x42e/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: rfcomm_mutex --> &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(rfcomm_mutex); *** DEADLOCK *** 4 locks held by kworker/u5:0/146: #0: ffff888072613938 ((wq_completion)hci3#2){+.+.}-{0:0}, at: process_one_work+0x75c/0xff0 kernel/workqueue.c:-1 #1: ffffc9000173fd00 ((work_completion)(&hdev->rx_work)){+.+.}-{0:0}, at: process_one_work+0x79e/0xff0 kernel/workqueue.c:2285 #2: ffff888023cb4478 (&hdev->lock){+.+.}-{3:3}, at: hci_auth_complete_evt+0xbc/0xbb0 net/bluetooth/hci_event.c:3035 #3: ffffffff8d593e48 (hci_cb_list_lock){+.+.}-{3:3}, at: hci_auth_cfm include/net/bluetooth/hci_core.h:1540 [inline] #3: ffffffff8d593e48 (hci_cb_list_lock){+.+.}-{3:3}, at: hci_auth_complete_evt+0x308/0xbb0 net/bluetooth/hci_event.c:3067 stack backtrace: CPU: 0 PID: 146 Comm: kworker/u5:0 Not tainted syzkaller #0 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 07/24/2026 Workqueue: hci3 hci_rx_work Call Trace: dump_stack_lvl+0x188/0x250 lib/dump_stack.c:106 check_noncircular+0x296/0x330 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+0x2c66/0x7b50 kernel/locking/lockdep.c:5012 lock_acquire+0x19e/0x400 kernel/locking/lockdep.c:5625 __mutex_lock_common+0x1e5/0x2400 kernel/locking/mutex.c:596 __mutex_lock kernel/locking/mutex.c:729 [inline] mutex_lock_nested+0x17/0x20 kernel/locking/mutex.c:743 rfcomm_security_cfm+0x95/0x780 net/bluetooth/rfcomm/core.c:2210 hci_auth_cfm include/net/bluetooth/hci_core.h:1543 [inline] hci_auth_complete_evt+0x388/0xbb0 net/bluetooth/hci_event.c:3067 hci_event_packet+0x701/0x1310 net/bluetooth/hci_event.c:6439 hci_rx_work+0x255/0xa10 net/bluetooth/hci_core.c:5190 process_one_work+0x867/0xff0 kernel/workqueue.c:2310 worker_thread+0xad7/0x12a0 kernel/workqueue.c:2457 kthread+0x42e/0x520 kernel/kthread.c:334 ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:287 Bluetooth: hci0: hardware error 0x00