====================================================== WARNING: possible circular locking dependency detected syzkaller #0 Not tainted ------------------------------------------------------ kworker/u5:1/4329 is trying to acquire lock: ffff800017bb6ac8 (rfcomm_mutex){+.+.}-{3:3}, at: rfcomm_security_cfm+0x9c/0x674 net/bluetooth/rfcomm/core.c:2210 but task is already holding lock: ffff800017b94328 (hci_cb_list_lock){+.+.}-{3:3}, at: hci_auth_cfm include/net/bluetooth/hci_core.h:1854 [inline] ffff800017b94328 (hci_cb_list_lock){+.+.}-{3:3}, at: hci_auth_complete_evt+0x280/0xa68 net/bluetooth/hci_event.c:3494 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+0x1a0/0x1f3c kernel/locking/mutex.c:603 __mutex_lock kernel/locking/mutex.c:747 [inline] mutex_lock_nested+0x38/0x44 kernel/locking/mutex.c:799 hci_connect_cfm include/net/bluetooth/hci_core.h:1818 [inline] hci_remote_features_evt+0x410/0x840 net/bluetooth/hci_event.c:3734 hci_event_func net/bluetooth/hci_event.c:7314 [inline] hci_event_packet+0x698/0xe60 net/bluetooth/hci_event.c:7366 hci_rx_work+0x310/0xa70 net/bluetooth/hci_core.c:4006 process_one_work+0x7e4/0x13bc kernel/workqueue.c:2292 worker_thread+0x8cc/0xfe8 kernel/workqueue.c:2439 kthread+0x254/0x2e0 kernel/kthread.c:376 ret_from_fork+0x10/0x20 arch/arm64/kernel/entry.S:850 -> #1 (&hdev->lock){+.+.}-{3:3}: __mutex_lock_common+0x1a0/0x1f3c kernel/locking/mutex.c:603 __mutex_lock kernel/locking/mutex.c:747 [inline] mutex_lock_nested+0x38/0x44 kernel/locking/mutex.c:799 l2cap_chan_connect+0xd0/0xba0 net/bluetooth/l2cap_core.c:7284 l2cap_sock_connect+0x414/0x600 net/bluetooth/l2cap_sock.c:257 kernel_connect+0x124/0x190 net/socket.c:3555 rfcomm_session_create net/bluetooth/rfcomm/core.c:807 [inline] __rfcomm_dlc_open net/bluetooth/rfcomm/core.c:384 [inline] rfcomm_dlc_open+0x4f4/0xcf4 net/bluetooth/rfcomm/core.c:427 rfcomm_sock_connect+0x25c/0x57c net/bluetooth/rfcomm/sock.c:421 __sys_connect_file net/socket.c:2011 [inline] __sys_connect+0x28c/0x2b4 net/socket.c:2028 __do_sys_connect net/socket.c:2038 [inline] __se_sys_connect net/socket.c:2035 [inline] __arm64_sys_connect+0x7c/0x94 net/socket.c:2035 __invoke_syscall arch/arm64/kernel/syscall.c:38 [inline] invoke_syscall+0x98/0x290 arch/arm64/kernel/syscall.c:52 el0_svc_common+0x13c/0x258 arch/arm64/kernel/syscall.c:140 do_el0_svc+0x5c/0x134 arch/arm64/kernel/syscall.c:204 el0_svc+0x58/0x128 arch/arm64/kernel/entry-common.c:637 el0t_64_sync_handler+0x84/0xf0 arch/arm64/kernel/entry-common.c:655 el0t_64_sync+0x18c/0x190 arch/arm64/kernel/entry.S:585 -> #0 (rfcomm_mutex){+.+.}-{3:3}: check_prev_add kernel/locking/lockdep.c:3095 [inline] check_prevs_add kernel/locking/lockdep.c:3214 [inline] validate_chain kernel/locking/lockdep.c:3830 [inline] __lock_acquire+0x2808/0x6634 kernel/locking/lockdep.c:5063 lock_acquire+0x20c/0x638 kernel/locking/lockdep.c:5678 __mutex_lock_common+0x1a0/0x1f3c kernel/locking/mutex.c:603 __mutex_lock kernel/locking/mutex.c:747 [inline] mutex_lock_nested+0x38/0x44 kernel/locking/mutex.c:799 rfcomm_security_cfm+0x9c/0x674 net/bluetooth/rfcomm/core.c:2210 hci_auth_cfm include/net/bluetooth/hci_core.h:1857 [inline] hci_auth_complete_evt+0x2e4/0xa68 net/bluetooth/hci_event.c:3494 hci_event_func net/bluetooth/hci_event.c:7314 [inline] hci_event_packet+0x698/0xe60 net/bluetooth/hci_event.c:7366 hci_rx_work+0x310/0xa70 net/bluetooth/hci_core.c:4006 process_one_work+0x7e4/0x13bc kernel/workqueue.c:2292 worker_thread+0x8cc/0xfe8 kernel/workqueue.c:2439 kthread+0x254/0x2e0 kernel/kthread.c:376 ret_from_fork+0x10/0x20 arch/arm64/kernel/entry.S:850 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/u5:1/4329: #0: ffff0000d3cd2938 ((wq_completion)hci2#2){+.+.}-{0:0}, at: process_one_work+0x69c/0x13bc kernel/workqueue.c:-1 #1: ffff8000210a7c40 ((work_completion)(&hdev->rx_work)){+.+.}-{0:0}, at: process_one_work+0x6e8/0x13bc kernel/workqueue.c:2267 #2: ffff0000cd6fc428 (&hdev->lock){+.+.}-{3:3}, at: hci_auth_complete_evt+0x94/0xa68 net/bluetooth/hci_event.c:3462 #3: ffff800017b94328 (hci_cb_list_lock){+.+.}-{3:3}, at: hci_auth_cfm include/net/bluetooth/hci_core.h:1854 [inline] #3: ffff800017b94328 (hci_cb_list_lock){+.+.}-{3:3}, at: hci_auth_complete_evt+0x280/0xa68 net/bluetooth/hci_event.c:3494 stack backtrace: CPU: 0 PID: 4329 Comm: kworker/u5:1 Not tainted syzkaller #0 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 08/14/2026 Workqueue: hci2 hci_rx_work Call trace: dump_backtrace+0x1c4/0x1f0 arch/arm64/kernel/stacktrace.c:158 show_stack+0x2c/0x3c arch/arm64/kernel/stacktrace.c:165 __dump_stack+0x30/0x40 lib/dump_stack.c:88 dump_stack_lvl+0xf4/0x15c lib/dump_stack.c:106 dump_stack+0x1c/0x5c lib/dump_stack.c:113 print_circular_bug+0x148/0x1b0 kernel/locking/lockdep.c:2048 check_noncircular+0x264/0x2f8 kernel/locking/lockdep.c:2170 check_prev_add kernel/locking/lockdep.c:3095 [inline] check_prevs_add kernel/locking/lockdep.c:3214 [inline] validate_chain kernel/locking/lockdep.c:3830 [inline] __lock_acquire+0x2808/0x6634 kernel/locking/lockdep.c:5063 lock_acquire+0x20c/0x638 kernel/locking/lockdep.c:5678 __mutex_lock_common+0x1a0/0x1f3c kernel/locking/mutex.c:603 __mutex_lock kernel/locking/mutex.c:747 [inline] mutex_lock_nested+0x38/0x44 kernel/locking/mutex.c:799 rfcomm_security_cfm+0x9c/0x674 net/bluetooth/rfcomm/core.c:2210 hci_auth_cfm include/net/bluetooth/hci_core.h:1857 [inline] hci_auth_complete_evt+0x2e4/0xa68 net/bluetooth/hci_event.c:3494 hci_event_func net/bluetooth/hci_event.c:7314 [inline] hci_event_packet+0x698/0xe60 net/bluetooth/hci_event.c:7366 hci_rx_work+0x310/0xa70 net/bluetooth/hci_core.c:4006 process_one_work+0x7e4/0x13bc kernel/workqueue.c:2292 worker_thread+0x8cc/0xfe8 kernel/workqueue.c:2439 kthread+0x254/0x2e0 kernel/kthread.c:376 ret_from_fork+0x10/0x20 arch/arm64/kernel/entry.S:850 Bluetooth: hci2: command 0x0406 tx timeout