====================================================== WARNING: possible circular locking dependency detected 6.2.0-next-20230224 #1 Not tainted ------------------------------------------------------ syz-executor.3/271 is trying to acquire lock: ffff88800bb78880 ((work_completion)(&hdev->cmd_sync_work)){+.+.}-{0:0}, at: __flush_work+0xdd/0xd80 but task is already holding lock: ffff88800bb78920 (&hdev->cmd_sync_work_lock){+.+.}-{3:3}, at: hci_cmd_sync_clear+0x45/0x250 which lock already depends on the new lock. the existing dependency chain (in reverse order) is: -> #1 (&hdev->cmd_sync_work_lock){+.+.}-{3:3}: __mutex_lock+0x133/0x14a0 hci_cmd_sync_work+0x1e6/0x320 process_one_work+0xa0f/0x1790 worker_thread+0x63b/0x1260 kthread+0x2e9/0x3a0 ret_from_fork+0x2c/0x50 -> #0 ((work_completion)(&hdev->cmd_sync_work)){+.+.}-{0:0}: __lock_acquire+0x2d56/0x6380 lock_acquire.part.0+0xea/0x320 __flush_work+0x109/0xd80 __cancel_work_timer+0x39c/0x4e0 hci_cmd_sync_clear+0x52/0x250 hci_unregister_dev+0xf9/0x410 vhci_release+0x80/0x100 __fput+0x263/0xa40 task_work_run+0x174/0x280 do_exit+0xad8/0x2800 do_group_exit+0xd4/0x2a0 get_signal+0x23c8/0x2450 arch_do_signal_or_restart+0x79/0x590 exit_to_user_mode_prepare+0x122/0x190 syscall_exit_to_user_mode+0x1d/0x50 do_syscall_64+0x4c/0x90 entry_SYSCALL_64_after_hwframe+0x72/0xdc other info that might help us debug this: Possible unsafe locking scenario: CPU0 CPU1 ---- ---- lock(&hdev->cmd_sync_work_lock); lock((work_completion)(&hdev->cmd_sync_work)); lock(&hdev->cmd_sync_work_lock); lock((work_completion)(&hdev->cmd_sync_work)); *** DEADLOCK *** 1 lock held by syz-executor.3/271: #0: ffff88800bb78920 (&hdev->cmd_sync_work_lock){+.+.}-{3:3}, at: hci_cmd_sync_clear+0x45/0x250 stack backtrace: CPU: 1 PID: 271 Comm: syz-executor.3 Not tainted 6.2.0-next-20230224 #1 Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS 1.12.0-1 04/01/2014 Call Trace: dump_stack_lvl+0x91/0xf0 check_noncircular+0x263/0x2e0 __lock_acquire+0x2d56/0x6380 lock_acquire.part.0+0xea/0x320 __flush_work+0x109/0xd80 __cancel_work_timer+0x39c/0x4e0 hci_cmd_sync_clear+0x52/0x250 hci_unregister_dev+0xf9/0x410 vhci_release+0x80/0x100 __fput+0x263/0xa40 task_work_run+0x174/0x280 do_exit+0xad8/0x2800 do_group_exit+0xd4/0x2a0 get_signal+0x23c8/0x2450 arch_do_signal_or_restart+0x79/0x590 exit_to_user_mode_prepare+0x122/0x190 syscall_exit_to_user_mode+0x1d/0x50 do_syscall_64+0x4c/0x90 entry_SYSCALL_64_after_hwframe+0x72/0xdc RIP: 0033:0x7fde23eed13a Code: Unable to access opcode bytes at 0x7fde23eed110. RSP: 002b:00007ffc0bd22d78 EFLAGS: 00000246 ORIG_RAX: 0000000000000037 RAX: fffffffffffffffe RBX: 0000000000000029 RCX: 00007fde23eed13a RDX: 0000000000000040 RSI: 0000000000000029 RDI: 0000000000000003 RBP: 0000000000000003 R08: 00007ffc0bd22dac R09: ff00000000000000 R10: 00007fde23fce668 R11: 0000000000000246 R12: 00007ffc0bd22dac R13: 00007fde23f4ece6 R14: 00007fde23fce668 R15: 00007fde23fce660 memfd_create() without MFD_EXEC nor MFD_NOEXEC_SEAL, pid=3904 'syz-executor.6' Bluetooth: hci0: unexpected cc 0x0c03 length: 249 > 1 Bluetooth: hci0: unexpected cc 0x1003 length: 249 > 9 Bluetooth: hci0: unexpected cc 0x1001 length: 249 > 9 Bluetooth: hci0: unexpected cc 0x0c23 length: 249 > 4 Bluetooth: hci0: unexpected cc 0x0c25 length: 249 > 3 Bluetooth: hci0: unexpected cc 0x0c38 length: 249 > 2 Bluetooth: hci3: unexpected cc 0x0c03 length: 249 > 1 Bluetooth: hci3: unexpected cc 0x1003 length: 249 > 9 Bluetooth: hci3: unexpected cc 0x1001 length: 249 > 9 Bluetooth: hci3: unexpected cc 0x0c23 length: 249 > 4 Bluetooth: hci3: unexpected cc 0x0c25 length: 249 > 3 Bluetooth: hci3: unexpected cc 0x0c38 length: 249 > 2 Bluetooth: hci6: unexpected cc 0x0c03 length: 249 > 1 Bluetooth: hci4: unexpected cc 0x0c03 length: 249 > 1 Bluetooth: hci4: unexpected cc 0x1003 length: 249 > 9 Bluetooth: hci6: unexpected cc 0x1003 length: 249 > 9 Bluetooth: hci4: unexpected cc 0x1001 length: 249 > 9 Bluetooth: hci6: unexpected cc 0x1001 length: 249 > 9 Bluetooth: hci4: unexpected cc 0x0c23 length: 249 > 4 Bluetooth: hci6: unexpected cc 0x0c23 length: 249 > 4 Bluetooth: hci4: unexpected cc 0x0c25 length: 249 > 3 Bluetooth: hci6: unexpected cc 0x0c25 length: 249 > 3 Bluetooth: hci6: unexpected cc 0x0c38 length: 249 > 2 Bluetooth: hci4: unexpected cc 0x0c38 length: 249 > 2 Bluetooth: hci2: unexpected cc 0x0c03 length: 249 > 1 Bluetooth: hci2: unexpected cc 0x1003 length: 249 > 9 Bluetooth: hci2: unexpected cc 0x1001 length: 249 > 9 Bluetooth: hci2: unexpected cc 0x0c23 length: 249 > 4 Bluetooth: hci2: unexpected cc 0x0c25 length: 249 > 3 Bluetooth: hci2: unexpected cc 0x0c38 length: 249 > 2 Bluetooth: hci0: command 0x0409 tx timeout Bluetooth: hci5: Opcode 0x c03 failed: -110 Bluetooth: hci3: command 0x0409 tx timeout Bluetooth: hci2: command 0x0409 tx timeout Bluetooth: hci6: command 0x0409 tx timeout Bluetooth: hci4: command 0x0409 tx timeout Bluetooth: hci0: command 0x041b tx timeout Bluetooth: hci3: command 0x041b tx timeout Bluetooth: hci4: command 0x041b tx timeout Bluetooth: hci6: command 0x041b tx timeout Bluetooth: hci2: command 0x041b tx timeout Bluetooth: hci0: command 0x040f tx timeout Bluetooth: hci3: command 0x040f tx timeout Bluetooth: hci2: command 0x040f tx timeout Bluetooth: hci6: command 0x040f tx timeout Bluetooth: hci4: command 0x040f tx timeout Bluetooth: hci5: Opcode 0x c03 failed: -110