Bluetooth: hci0: hardware error 0x00 ====================================================== WARNING: possible circular locking dependency detected syzkaller #0 Not tainted ------------------------------------------------------ kworker/u5:1/4114 is trying to acquire lock: ffff0000c8c04120 (sk_lock-AF_BLUETOOTH-BTPROTO_SCO){+.+.}-{0:0}, at: lock_sock include/net/sock.h:1744 [inline] ffff0000c8c04120 (sk_lock-AF_BLUETOOTH-BTPROTO_SCO){+.+.}-{0:0}, at: sco_conn_del+0x120/0x49c net/bluetooth/sco.c:206 but task is already holding lock: ffff80001650b148 (hci_cb_list_lock){+.+.}-{3:3}, at: hci_disconn_cfm include/net/bluetooth/hci_core.h:1517 [inline] ffff80001650b148 (hci_cb_list_lock){+.+.}-{3:3}, at: hci_conn_hash_flush+0xb0/0x210 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+0x194/0x1f14 kernel/locking/mutex.c:596 __mutex_lock kernel/locking/mutex.c:729 [inline] mutex_lock_nested+0xac/0x11c kernel/locking/mutex.c:743 hci_connect_cfm include/net/bluetooth/hci_core.h:1502 [inline] hci_remote_features_evt+0x428/0x864 net/bluetooth/hci_event.c:3372 hci_event_packet+0x564/0x1208 net/bluetooth/hci_event.c:6449 hci_rx_work+0x1cc/0x868 net/bluetooth/hci_core.c:5164 process_one_work+0x79c/0x1138 kernel/workqueue.c:2310 worker_thread+0x8f4/0x1034 kernel/workqueue.c:2457 kthread+0x374/0x454 kernel/kthread.c:334 ret_from_fork+0x10/0x20 arch/arm64/kernel/entry.S:856 -> #1 (&hdev->lock){+.+.}-{3:3}: __mutex_lock_common+0x194/0x1f14 kernel/locking/mutex.c:596 __mutex_lock kernel/locking/mutex.c:729 [inline] mutex_lock_nested+0xac/0x11c kernel/locking/mutex.c:743 sco_sock_connect+0x160/0x7c0 net/bluetooth/sco.c:604 __sys_connect_file net/socket.c:1932 [inline] __sys_connect+0x28c/0x2b4 net/socket.c:1949 __do_sys_connect net/socket.c:1959 [inline] __se_sys_connect net/socket.c:1956 [inline] __arm64_sys_connect+0x7c/0x94 net/socket.c:1956 __invoke_syscall arch/arm64/kernel/syscall.c:38 [inline] invoke_syscall+0x98/0x2b0 arch/arm64/kernel/syscall.c:52 el0_svc_common+0x138/0x258 arch/arm64/kernel/syscall.c:142 do_el0_svc+0x58/0x13c arch/arm64/kernel/syscall.c:181 el0_svc+0x78/0x1d0 arch/arm64/kernel/entry-common.c:608 el0t_64_sync_handler+0xcc/0xe4 arch/arm64/kernel/entry-common.c:626 el0t_64_sync+0x1a0/0x1a4 arch/arm64/kernel/entry.S:584 -> #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+0x2870/0x67ec kernel/locking/lockdep.c:5012 lock_acquire+0x1f4/0x618 kernel/locking/lockdep.c:5623 lock_sock_nested+0xd8/0x1d4 net/core/sock.c:3259 lock_sock include/net/sock.h:1744 [inline] sco_conn_del+0x120/0x49c net/bluetooth/sco.c:206 sco_disconn_cfm+0x8c/0xd8 net/bluetooth/sco.c:1223 hci_disconn_cfm include/net/bluetooth/hci_core.h:1520 [inline] hci_conn_hash_flush+0x108/0x210 net/bluetooth/hci_conn.c:1622 hci_dev_do_close+0x7e4/0xfe4 net/bluetooth/hci_core.c:1795 hci_error_reset+0xe8/0x298 net/bluetooth/hci_core.c:2341 process_one_work+0x79c/0x1138 kernel/workqueue.c:2310 worker_thread+0x8f4/0x1034 kernel/workqueue.c:2457 kthread+0x374/0x454 kernel/kthread.c:334 ret_from_fork+0x10/0x20 arch/arm64/kernel/entry.S:856 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/u5:1/4114: #0: ffff0000d78e7938 ((wq_completion)hci0){+.+.}-{0:0}, at: process_one_work+0x678/0x1138 kernel/workqueue.c:2283 #1: ffff80001fb57c00 ((work_completion)(&hdev->error_reset)){+.+.}-{0:0}, at: process_one_work+0x6b8/0x1138 kernel/workqueue.c:2285 #2: ffff0000d6df8ff0 (&hdev->req_lock){+.+.}-{3:3}, at: hci_dev_do_close+0x60/0xfe4 net/bluetooth/hci_core.c:1737 #3: ffff0000d6df8078 (&hdev->lock){+.+.}-{3:3}, at: hci_dev_do_close+0x334/0xfe4 net/bluetooth/hci_core.c:1782 #4: ffff80001650b148 (hci_cb_list_lock){+.+.}-{3:3}, at: hci_disconn_cfm include/net/bluetooth/hci_core.h:1517 [inline] #4: ffff80001650b148 (hci_cb_list_lock){+.+.}-{3:3}, at: hci_conn_hash_flush+0xb0/0x210 net/bluetooth/hci_conn.c:1622 stack backtrace: CPU: 1 PID: 4114 Comm: kworker/u5:1 Not tainted syzkaller #0 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/26/2026 Workqueue: hci0 hci_error_reset Call trace: dump_backtrace+0x0/0x458 arch/arm64/kernel/stacktrace.c:152 show_stack+0x2c/0x3c arch/arm64/kernel/stacktrace.c:216 __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:2011 check_noncircular+0x264/0x2f8 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+0x2870/0x67ec kernel/locking/lockdep.c:5012 lock_acquire+0x1f4/0x618 kernel/locking/lockdep.c:5623 lock_sock_nested+0xd8/0x1d4 net/core/sock.c:3259 lock_sock include/net/sock.h:1744 [inline] sco_conn_del+0x120/0x49c net/bluetooth/sco.c:206 sco_disconn_cfm+0x8c/0xd8 net/bluetooth/sco.c:1223 hci_disconn_cfm include/net/bluetooth/hci_core.h:1520 [inline] hci_conn_hash_flush+0x108/0x210 net/bluetooth/hci_conn.c:1622 hci_dev_do_close+0x7e4/0xfe4 net/bluetooth/hci_core.c:1795 hci_error_reset+0xe8/0x298 net/bluetooth/hci_core.c:2341 process_one_work+0x79c/0x1138 kernel/workqueue.c:2310 worker_thread+0x8f4/0x1034 kernel/workqueue.c:2457 kthread+0x374/0x454 kernel/kthread.c:334 ret_from_fork+0x10/0x20 arch/arm64/kernel/entry.S:856