====================================================== WARNING: possible circular locking dependency detected syzkaller #0 Not tainted ------------------------------------------------------ syz.0.17/6697 is trying to acquire lock: ffff0000d463f040 ((work_completion)(&(&conn->info_timer)->work)){+.+.}-{0:0}, at: touch_work_lockdep_map+0x70/0x118 kernel/workqueue.c:3920 but task is already holding lock: ffff0000d463f338 (&conn->lock#2){+.+.}-{4:4}, at: l2cap_conn_del+0x74/0x5f0 net/bluetooth/l2cap_core.c:1762 which lock already depends on the new lock. the existing dependency chain (in reverse order) is: -> #1 (&conn->lock#2){+.+.}-{4:4}: __mutex_lock_common+0x1d0/0x2678 kernel/locking/mutex.c:598 __mutex_lock kernel/locking/mutex.c:760 [inline] mutex_lock_nested+0x2c/0x38 kernel/locking/mutex.c:812 l2cap_info_timeout+0x70/0xb0 net/bluetooth/l2cap_core.c:1668 process_one_work+0x7e8/0x155c kernel/workqueue.c:3236 process_scheduled_works kernel/workqueue.c:3319 [inline] worker_thread+0x958/0xed8 kernel/workqueue.c:3400 kthread+0x5fc/0x75c kernel/kthread.c:463 ret_from_fork+0x10/0x20 arch/arm64/kernel/entry.S:844 -> #0 ((work_completion)(&(&conn->info_timer)->work)){+.+.}-{0:0}: check_prev_add kernel/locking/lockdep.c:3165 [inline] check_prevs_add kernel/locking/lockdep.c:3284 [inline] validate_chain kernel/locking/lockdep.c:3908 [inline] __lock_acquire+0x1774/0x30a4 kernel/locking/lockdep.c:5237 lock_acquire+0x14c/0x2e0 kernel/locking/lockdep.c:5868 touch_work_lockdep_map+0x98/0x118 kernel/workqueue.c:3922 start_flush_work kernel/workqueue.c:4176 [inline] __flush_work+0x4fc/0x8c0 kernel/workqueue.c:4208 __cancel_work_sync kernel/workqueue.c:4364 [inline] cancel_delayed_work_sync+0xc4/0x120 kernel/workqueue.c:4438 l2cap_conn_del+0x460/0x5f0 net/bluetooth/l2cap_core.c:1796 l2cap_disconn_cfm+0x90/0xe0 net/bluetooth/l2cap_core.c:7325 hci_disconn_cfm include/net/bluetooth/hci_core.h:2097 [inline] hci_conn_hash_flush+0x108/0x218 net/bluetooth/hci_conn.c:2599 hci_dev_close_sync+0x89c/0x1154 net/bluetooth/hci_sync.c:5294 hci_dev_do_close net/bluetooth/hci_core.c:501 [inline] hci_unregister_dev+0x204/0x4c0 net/bluetooth/hci_core.c:2715 vhci_release+0x12c/0x17c drivers/bluetooth/hci_vhci.c:690 __fput+0x340/0x75c fs/file_table.c:468 ____fput+0x20/0x58 fs/file_table.c:496 task_work_run+0x1dc/0x260 kernel/task_work.c:227 exit_task_work include/linux/task_work.h:40 [inline] do_exit+0x524/0x1a14 kernel/exit.c:961 do_group_exit+0x194/0x22c kernel/exit.c:1102 get_signal+0x11dc/0x12f8 kernel/signal.c:3034 arch_do_signal_or_restart+0x274/0x4434 arch/arm64/kernel/signal.c:1619 exit_to_user_mode_loop+0x7c/0x168 kernel/entry/common.c:40 exit_to_user_mode_prepare include/linux/irq-entry-common.h:225 [inline] arm64_exit_to_user_mode arch/arm64/kernel/entry-common.c:103 [inline] el0_svc+0x170/0x254 arch/arm64/kernel/entry-common.c:745 el0t_64_sync_handler+0x84/0x12c arch/arm64/kernel/entry-common.c:763 el0t_64_sync+0x198/0x19c arch/arm64/kernel/entry.S:596 other info that might help us debug this: Possible unsafe locking scenario: CPU0 CPU1 ---- ---- lock(&conn->lock#2); lock((work_completion)(&(&conn->info_timer)->work)); lock(&conn->lock#2); lock((work_completion)(&(&conn->info_timer)->work)); *** DEADLOCK *** 5 locks held by syz.0.17/6697: #0: ffff0000d4cd0dc0 (&hdev->req_lock){+.+.}-{4:4}, at: hci_dev_do_close net/bluetooth/hci_core.c:499 [inline] #0: ffff0000d4cd0dc0 (&hdev->req_lock){+.+.}-{4:4}, at: hci_unregister_dev+0x1fc/0x4c0 net/bluetooth/hci_core.c:2715 #1: ffff0000d4cd00b8 (&hdev->lock){+.+.}-{4:4}, at: hci_dev_close_sync+0x4c4/0x1154 net/bluetooth/hci_sync.c:5282 #2: ffff800092bf0da8 (hci_cb_list_lock){+.+.}-{4:4}, at: hci_disconn_cfm include/net/bluetooth/hci_core.h:2094 [inline] #2: ffff800092bf0da8 (hci_cb_list_lock){+.+.}-{4:4}, at: hci_conn_hash_flush+0xb0/0x218 net/bluetooth/hci_conn.c:2599 #3: ffff0000d463f338 (&conn->lock#2){+.+.}-{4:4}, at: l2cap_conn_del+0x74/0x5f0 net/bluetooth/l2cap_core.c:1762 #4: ffff80008f9d9620 (rcu_read_lock){....}-{1:3}, at: rcu_lock_acquire+0x10/0x4c include/linux/rcupdate.h:330 stack backtrace: CPU: 1 UID: 0 PID: 6697 Comm: syz.0.17 Not tainted syzkaller #0 PREEMPT Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 06/30/2025 Call trace: show_stack+0x2c/0x3c arch/arm64/kernel/stacktrace.c:499 (C) __dump_stack+0x30/0x40 lib/dump_stack.c:94 dump_stack_lvl+0xd8/0x12c lib/dump_stack.c:120 dump_stack+0x1c/0x28 lib/dump_stack.c:129 print_circular_bug+0x324/0x32c kernel/locking/lockdep.c:2043 check_noncircular+0x154/0x174 kernel/locking/lockdep.c:2175 check_prev_add kernel/locking/lockdep.c:3165 [inline] check_prevs_add kernel/locking/lockdep.c:3284 [inline] validate_chain kernel/locking/lockdep.c:3908 [inline] __lock_acquire+0x1774/0x30a4 kernel/locking/lockdep.c:5237 lock_acquire+0x14c/0x2e0 kernel/locking/lockdep.c:5868 touch_work_lockdep_map+0x98/0x118 kernel/workqueue.c:3922 start_flush_work kernel/workqueue.c:4176 [inline] __flush_work+0x4fc/0x8c0 kernel/workqueue.c:4208 __cancel_work_sync kernel/workqueue.c:4364 [inline] cancel_delayed_work_sync+0xc4/0x120 kernel/workqueue.c:4438 l2cap_conn_del+0x460/0x5f0 net/bluetooth/l2cap_core.c:1796 l2cap_disconn_cfm+0x90/0xe0 net/bluetooth/l2cap_core.c:7325 hci_disconn_cfm include/net/bluetooth/hci_core.h:2097 [inline] hci_conn_hash_flush+0x108/0x218 net/bluetooth/hci_conn.c:2599 hci_dev_close_sync+0x89c/0x1154 net/bluetooth/hci_sync.c:5294 hci_dev_do_close net/bluetooth/hci_core.c:501 [inline] hci_unregister_dev+0x204/0x4c0 net/bluetooth/hci_core.c:2715 vhci_release+0x12c/0x17c drivers/bluetooth/hci_vhci.c:690 __fput+0x340/0x75c fs/file_table.c:468 ____fput+0x20/0x58 fs/file_table.c:496 task_work_run+0x1dc/0x260 kernel/task_work.c:227 exit_task_work include/linux/task_work.h:40 [inline] do_exit+0x524/0x1a14 kernel/exit.c:961 do_group_exit+0x194/0x22c kernel/exit.c:1102 get_signal+0x11dc/0x12f8 kernel/signal.c:3034 arch_do_signal_or_restart+0x274/0x4434 arch/arm64/kernel/signal.c:1619 exit_to_user_mode_loop+0x7c/0x168 kernel/entry/common.c:40 exit_to_user_mode_prepare include/linux/irq-entry-common.h:225 [inline] arm64_exit_to_user_mode arch/arm64/kernel/entry-common.c:103 [inline] el0_svc+0x170/0x254 arch/arm64/kernel/entry-common.c:745 el0t_64_sync_handler+0x84/0x12c arch/arm64/kernel/entry-common.c:763 el0t_64_sync+0x198/0x19c arch/arm64/kernel/entry.S:596