====================================================== WARNING: possible circular locking dependency detected 4.14.262-syzkaller #0 Not tainted ------------------------------------------------------ syz-executor.0/13068 is trying to acquire lock: ("%s"hdev->name#2){+.+.}, at: [] start_flush_work kernel/workqueue.c:2861 [inline] ("%s"hdev->name#2){+.+.}, at: [] flush_work+0x387/0x770 kernel/workqueue.c:2893 but task is already holding lock: (&hdev->lock){+.+.}, at: [] hci_dev_do_close+0x264/0xd80 net/bluetooth/hci_core.c:1628 which lock already depends on the new lock. the existing dependency chain (in reverse order) is: -> #2 (&hdev->lock){+.+.}: __mutex_lock_common kernel/locking/mutex.c:756 [inline] __mutex_lock+0xc4/0x1310 kernel/locking/mutex.c:893 hci_cc_write_scan_enable net/bluetooth/hci_event.c:375 [inline] hci_cmd_complete_evt+0x4d34/0xb490 net/bluetooth/hci_event.c:2831 hci_event_packet+0x21ce/0x7510 net/bluetooth/hci_event.c:5346 hci_rx_work+0x427/0xb40 net/bluetooth/hci_core.c:4265 process_one_work+0x793/0x14a0 kernel/workqueue.c:2117 worker_thread+0x5cc/0xff0 kernel/workqueue.c:2251 kthread+0x30d/0x420 kernel/kthread.c:232 ret_from_fork+0x24/0x30 arch/x86/entry/entry_64.S:404 -> #1 ((&hdev->rx_work)){+.+.}: process_one_work+0x736/0x14a0 kernel/workqueue.c:2093 worker_thread+0x5cc/0xff0 kernel/workqueue.c:2251 kthread+0x30d/0x420 kernel/kthread.c:232 ret_from_fork+0x24/0x30 arch/x86/entry/entry_64.S:404 -> #0 ("%s"hdev->name#2){+.+.}: lock_acquire+0x170/0x3f0 kernel/locking/lockdep.c:3998 start_flush_work kernel/workqueue.c:2862 [inline] flush_work+0x3ac/0x770 kernel/workqueue.c:2893 __cancel_work_timer+0x321/0x460 kernel/workqueue.c:2965 hci_conn_del+0x52/0x6f0 net/bluetooth/hci_conn.c:575 hci_conn_hash_flush+0x19c/0x260 net/bluetooth/hci_conn.c:1394 hci_dev_do_close+0x57d/0xd80 net/bluetooth/hci_core.c:1641 hci_unregister_dev+0x143/0x420 net/bluetooth/hci_core.c:3208 vhci_release+0x70/0xe0 drivers/bluetooth/hci_vhci.c:354 __fput+0x25f/0x7a0 fs/file_table.c:210 task_work_run+0x11f/0x190 kernel/task_work.c:113 exit_task_work include/linux/task_work.h:22 [inline] do_exit+0xa44/0x2850 kernel/exit.c:868 do_group_exit+0x100/0x2e0 kernel/exit.c:965 get_signal+0x38d/0x1ca0 kernel/signal.c:2412 do_signal+0x7c/0x1550 arch/x86/kernel/signal.c:792 exit_to_usermode_loop+0x160/0x200 arch/x86/entry/common.c:160 prepare_exit_to_usermode arch/x86/entry/common.c:199 [inline] syscall_return_slowpath arch/x86/entry/common.c:270 [inline] do_syscall_64+0x4a3/0x640 arch/x86/entry/common.c:297 entry_SYSCALL_64_after_hwframe+0x46/0xbb other info that might help us debug this: Chain exists of: "%s"hdev->name#2 --> (&hdev->rx_work) --> &hdev->lock Possible unsafe locking scenario: CPU0 CPU1 ---- ---- lock(&hdev->lock); lock((&hdev->rx_work)); lock(&hdev->lock); lock("%s"hdev->name#2); *** DEADLOCK *** 2 locks held by syz-executor.0/13068: #0: (&hdev->req_lock){+.+.}, at: [] hci_dev_do_close+0xa8/0xd80 net/bluetooth/hci_core.c:1589 #1: (&hdev->lock){+.+.}, at: [] hci_dev_do_close+0x264/0xd80 net/bluetooth/hci_core.c:1628 stack backtrace: CPU: 0 PID: 13068 Comm: syz-executor.0 Not tainted 4.14.262-syzkaller #0 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 Call Trace: __dump_stack lib/dump_stack.c:17 [inline] dump_stack+0x1b2/0x281 lib/dump_stack.c:58 print_circular_bug.constprop.0.cold+0x2d7/0x41e kernel/locking/lockdep.c:1258 check_prev_add kernel/locking/lockdep.c:1905 [inline] check_prevs_add kernel/locking/lockdep.c:2022 [inline] validate_chain kernel/locking/lockdep.c:2464 [inline] __lock_acquire+0x2e0e/0x3f20 kernel/locking/lockdep.c:3491 lock_acquire+0x170/0x3f0 kernel/locking/lockdep.c:3998 start_flush_work kernel/workqueue.c:2862 [inline] flush_work+0x3ac/0x770 kernel/workqueue.c:2893 __cancel_work_timer+0x321/0x460 kernel/workqueue.c:2965 hci_conn_del+0x52/0x6f0 net/bluetooth/hci_conn.c:575 hci_conn_hash_flush+0x19c/0x260 net/bluetooth/hci_conn.c:1394 hci_dev_do_close+0x57d/0xd80 net/bluetooth/hci_core.c:1641 hci_unregister_dev+0x143/0x420 net/bluetooth/hci_core.c:3208 vhci_release+0x70/0xe0 drivers/bluetooth/hci_vhci.c:354 __fput+0x25f/0x7a0 fs/file_table.c:210 task_work_run+0x11f/0x190 kernel/task_work.c:113 exit_task_work include/linux/task_work.h:22 [inline] do_exit+0xa44/0x2850 kernel/exit.c:868 do_group_exit+0x100/0x2e0 kernel/exit.c:965 get_signal+0x38d/0x1ca0 kernel/signal.c:2412 do_signal+0x7c/0x1550 arch/x86/kernel/signal.c:792 exit_to_usermode_loop+0x160/0x200 arch/x86/entry/common.c:160 prepare_exit_to_usermode arch/x86/entry/common.c:199 [inline] syscall_return_slowpath arch/x86/entry/common.c:270 [inline] do_syscall_64+0x4a3/0x640 arch/x86/entry/common.c:297 entry_SYSCALL_64_after_hwframe+0x46/0xbb RIP: 0033:0x7f7d2921eeb9 RSP: 002b:00007f7d27b73218 EFLAGS: 00000246 ORIG_RAX: 00000000000000ca RAX: fffffffffffffe00 RBX: 00007f7d29332038 RCX: 00007f7d2921eeb9 RDX: 0000000000000000 RSI: 0000000000000080 RDI: 00007f7d29332038 RBP: 00007f7d29332030 R08: 0000000000000000 R09: 0000000000000000 R10: 0000000000000000 R11: 0000000000000246 R12: 00007f7d2933203c R13: 00007ffd85113ccf R14: 00007f7d27b73300 R15: 0000000000022000