====================================================== WARNING: possible circular locking dependency detected 6.16.0-rc1-syzkaller-g19272b37aa4f #0 Not tainted ------------------------------------------------------ syz.2.3/6632 is trying to acquire lock: ffff0000ccef3840 ((work_completion)(&(&conn->info_timer)->work)){+.+.}-{0:0}, at: touch_work_lockdep_map+0x70/0x118 kernel/workqueue.c:3922 but task is already holding lock: ffff0000ccef3b38 (&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+0x1d0/0x2190 kernel/locking/mutex.c:602 __mutex_lock kernel/locking/mutex.c:747 [inline] mutex_lock_nested+0x2c/0x38 kernel/locking/mutex.c:799 l2cap_info_timeout+0x70/0xb0 net/bluetooth/l2cap_core.c:1668 process_one_work+0x7e8/0x155c kernel/workqueue.c:3238 process_scheduled_works kernel/workqueue.c:3321 [inline] worker_thread+0x958/0xed8 kernel/workqueue.c:3402 kthread+0x5fc/0x75c kernel/kthread.c:464 ret_from_fork+0x10/0x20 arch/arm64/kernel/entry.S:847 -> #0 ((work_completion)(&(&conn->info_timer)->work)){+.+.}-{0:0}: check_prev_add kernel/locking/lockdep.c:3168 [inline] check_prevs_add kernel/locking/lockdep.c:3287 [inline] validate_chain kernel/locking/lockdep.c:3911 [inline] __lock_acquire+0x1774/0x30a4 kernel/locking/lockdep.c:5240 lock_acquire+0x14c/0x2e0 kernel/locking/lockdep.c:5871 touch_work_lockdep_map+0x98/0x118 kernel/workqueue.c:3924 start_flush_work kernel/workqueue.c:4178 [inline] __flush_work+0x4fc/0x8c0 kernel/workqueue.c:4210 __cancel_work_sync kernel/workqueue.c:4366 [inline] cancel_delayed_work_sync+0xc4/0x120 kernel/workqueue.c:4440 l2cap_conn_del+0x460/0x5f0 net/bluetooth/l2cap_core.c:1796 l2cap_disconn_cfm+0x90/0xe0 net/bluetooth/l2cap_core.c:7302 hci_disconn_cfm include/net/bluetooth/hci_core.h:2065 [inline] hci_conn_hash_flush+0x104/0x214 net/bluetooth/hci_conn.c:2543 hci_dev_close_sync+0x89c/0x1154 net/bluetooth/hci_sync.c:5225 hci_dev_do_close net/bluetooth/hci_core.c:483 [inline] hci_dev_close+0xe0/0x208 net/bluetooth/hci_core.c:508 hci_sock_ioctl+0x420/0x86c net/bluetooth/hci_sock.c:1135 sock_do_ioctl+0xf4/0x2b4 net/socket.c:1190 sock_ioctl+0x57c/0x84c net/socket.c:1311 vfs_ioctl fs/ioctl.c:51 [inline] __do_sys_ioctl fs/ioctl.c:907 [inline] __se_sys_ioctl fs/ioctl.c:893 [inline] __arm64_sys_ioctl+0x14c/0x1c4 fs/ioctl.c:893 __invoke_syscall arch/arm64/kernel/syscall.c:35 [inline] invoke_syscall+0x98/0x2b8 arch/arm64/kernel/syscall.c:49 el0_svc_common+0x130/0x23c arch/arm64/kernel/syscall.c:132 do_el0_svc+0x48/0x58 arch/arm64/kernel/syscall.c:151 el0_svc+0x58/0x17c arch/arm64/kernel/entry-common.c:767 el0t_64_sync_handler+0x78/0x108 arch/arm64/kernel/entry-common.c:786 el0t_64_sync+0x198/0x19c arch/arm64/kernel/entry.S:600 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.2.3/6632: #0: ffff0000c8994d80 (&hdev->req_lock){+.+.}-{4:4}, at: hci_dev_do_close net/bluetooth/hci_core.c:481 [inline] #0: ffff0000c8994d80 (&hdev->req_lock){+.+.}-{4:4}, at: hci_dev_close+0xd8/0x208 net/bluetooth/hci_core.c:508 #1: ffff0000c8994078 (&hdev->lock){+.+.}-{4:4}, at: hci_dev_close_sync+0x4c4/0x1154 net/bluetooth/hci_sync.c:5213 #2: ffff8000928d1288 (hci_cb_list_lock){+.+.}-{4:4}, at: hci_disconn_cfm include/net/bluetooth/hci_core.h:2062 [inline] #2: ffff8000928d1288 (hci_cb_list_lock){+.+.}-{4:4}, at: hci_conn_hash_flush+0xac/0x214 net/bluetooth/hci_conn.c:2543 #3: ffff0000ccef3b38 (&conn->lock#2){+.+.}-{4:4}, at: l2cap_conn_del+0x74/0x5f0 net/bluetooth/l2cap_core.c:1762 #4: ffff80008f749e40 (rcu_read_lock){....}-{1:3}, at: rcu_lock_acquire+0x10/0x4c include/linux/rcupdate.h:330 stack backtrace: CPU: 0 UID: 0 PID: 6632 Comm: syz.2.3 Not tainted 6.16.0-rc1-syzkaller-g19272b37aa4f #0 PREEMPT Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 05/07/2025 Call trace: show_stack+0x2c/0x3c arch/arm64/kernel/stacktrace.c:466 (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:2046 check_noncircular+0x154/0x174 kernel/locking/lockdep.c:2178 check_prev_add kernel/locking/lockdep.c:3168 [inline] check_prevs_add kernel/locking/lockdep.c:3287 [inline] validate_chain kernel/locking/lockdep.c:3911 [inline] __lock_acquire+0x1774/0x30a4 kernel/locking/lockdep.c:5240 lock_acquire+0x14c/0x2e0 kernel/locking/lockdep.c:5871 touch_work_lockdep_map+0x98/0x118 kernel/workqueue.c:3924 start_flush_work kernel/workqueue.c:4178 [inline] __flush_work+0x4fc/0x8c0 kernel/workqueue.c:4210 __cancel_work_sync kernel/workqueue.c:4366 [inline] cancel_delayed_work_sync+0xc4/0x120 kernel/workqueue.c:4440 l2cap_conn_del+0x460/0x5f0 net/bluetooth/l2cap_core.c:1796 l2cap_disconn_cfm+0x90/0xe0 net/bluetooth/l2cap_core.c:7302 hci_disconn_cfm include/net/bluetooth/hci_core.h:2065 [inline] hci_conn_hash_flush+0x104/0x214 net/bluetooth/hci_conn.c:2543 hci_dev_close_sync+0x89c/0x1154 net/bluetooth/hci_sync.c:5225 hci_dev_do_close net/bluetooth/hci_core.c:483 [inline] hci_dev_close+0xe0/0x208 net/bluetooth/hci_core.c:508 hci_sock_ioctl+0x420/0x86c net/bluetooth/hci_sock.c:1135 sock_do_ioctl+0xf4/0x2b4 net/socket.c:1190 sock_ioctl+0x57c/0x84c net/socket.c:1311 vfs_ioctl fs/ioctl.c:51 [inline] __do_sys_ioctl fs/ioctl.c:907 [inline] __se_sys_ioctl fs/ioctl.c:893 [inline] __arm64_sys_ioctl+0x14c/0x1c4 fs/ioctl.c:893 __invoke_syscall arch/arm64/kernel/syscall.c:35 [inline] invoke_syscall+0x98/0x2b8 arch/arm64/kernel/syscall.c:49 el0_svc_common+0x130/0x23c arch/arm64/kernel/syscall.c:132 do_el0_svc+0x48/0x58 arch/arm64/kernel/syscall.c:151 el0_svc+0x58/0x17c arch/arm64/kernel/entry-common.c:767 el0t_64_sync_handler+0x78/0x108 arch/arm64/kernel/entry-common.c:786 el0t_64_sync+0x198/0x19c arch/arm64/kernel/entry.S:600