[info] Using makefile-style concurrent boot in runlevel 2. [....] Starting enhanced syslogd: rsyslogd[ 15.319653][ C1] random: crng init done [?25l[?1c7[ ok 8[?25h[?0c. [....] Starting periodic command scheduler: cron[?25l[?1c7[ ok 8[?25h[?0c. [....] Starting OpenBSD Secure Shell server: sshd[?25l[?1c7[ ok 8[?25h[?0c. Debian GNU/Linux 7 syzkaller ttyS0 Warning: Permanently added '10.128.10.33' (ECDSA) to the list of known hosts. executing program syzkaller login: [ 51.546942][ T12] usb 1-1: new high-speed USB device number 2 using dummy_hcd [ 51.786971][ T12] usb 1-1: Using ep0 maxpacket: 8 [ 51.907032][ T12] usb 1-1: config 0 has an invalid interface number: 219 but max is 0 [ 51.915998][ T12] usb 1-1: config 0 has no interface number 0 [ 51.923571][ T12] usb 1-1: config 0 interface 219 altsetting 0 endpoint 0xF has an invalid bInterval 0, changing to 7 [ 51.936773][ T12] usb 1-1: config 0 interface 219 altsetting 0 endpoint 0x83 has an invalid bInterval 0, changing to 7 [ 51.948487][ T12] usb 1-1: New USB device found, idVendor=0694, idProduct=0001, bcdDevice=eb.88 [ 51.957850][ T12] usb 1-1: New USB device strings: Mfr=0, Product=0, SerialNumber=0 [ 51.967934][ T12] usb 1-1: config 0 descriptor?? [ 52.226994][ T12] legousbtower 1-1:0.219: LEGO USB Tower firmware version is 129.136 build 65535 [ 52.240920][ T12] legousbtower 1-1:0.219: LEGO USB Tower #-160 now attached to major 180 minor 0 [ 53.487157][ T1727] usb 1-1: LEGO USB Tower reset control request failed [ 53.495261][ T12] usb 1-1: USB disconnect, device number 2 [ 53.506015][ T12] [ 53.508450][ T12] ====================================================== [ 53.515584][ T12] WARNING: possible circular locking dependency detected [ 53.522605][ T12] 5.3.0-rc7+ #0 Not tainted [ 53.527079][ T12] ------------------------------------------------------ [ 53.534254][ T12] kworker/0:1/12 is trying to acquire lock: [ 53.540121][ T12] 00000000482277da (minor_rwsem){++++}, at: usb_deregister_dev+0x95/0x230 [ 53.548695][ T12] [ 53.548695][ T12] but task is already holding lock: [ 53.556247][ T12] 00000000bdce1735 (open_disc_mutex){+.+.}, at: tower_disconnect+0x45/0x300 [ 53.564961][ T12] [ 53.564961][ T12] which lock already depends on the new lock. [ 53.564961][ T12] [ 53.575348][ T12] [ 53.575348][ T12] the existing dependency chain (in reverse order) is: [ 53.584337][ T12] [ 53.584337][ T12] -> #1 (open_disc_mutex){+.+.}: [ 53.591428][ T12] __mutex_lock+0x158/0x1360 [ 53.596509][ T12] tower_open+0xce/0x9b0 [ 53.601243][ T12] usb_open+0x1df/0x270 [ 53.605896][ T12] chrdev_open+0x219/0x5c0 [ 53.610872][ T12] do_dentry_open+0x494/0x1120 [ 53.616169][ T12] path_openat+0x1430/0x3f50 [ 53.621394][ T12] do_filp_open+0x1a1/0x280 [ 53.626914][ T12] do_sys_open+0x3c0/0x580 [ 53.631838][ T12] do_syscall_64+0xb7/0x580 [ 53.636852][ T12] entry_SYSCALL_64_after_hwframe+0x49/0xbe [ 53.643411][ T12] [ 53.643411][ T12] -> #0 (minor_rwsem){++++}: [ 53.650171][ T12] __lock_acquire+0x1f7c/0x3b50 [ 53.655515][ T12] lock_acquire+0x127/0x320 [ 53.660515][ T12] down_write+0x92/0x150 [ 53.665614][ T12] usb_deregister_dev+0x95/0x230 [ 53.671055][ T12] tower_disconnect+0xa8/0x300 [ 53.676397][ T12] usb_unbind_interface+0x1bd/0x8a0 [ 53.682113][ T12] device_release_driver_internal+0x42f/0x500 [ 53.688671][ T12] bus_remove_device+0x2dc/0x4a0 [ 53.694113][ T12] device_del+0x420/0xb10 [ 53.698961][ T12] usb_disable_device+0x211/0x690 [ 53.704493][ T12] usb_disconnect+0x284/0x8d0 [ 53.709662][ T12] hub_event+0x1454/0x3640 [ 53.714661][ T12] process_one_work+0x92b/0x1530 [ 53.720102][ T12] worker_thread+0x96/0xe20 [ 53.725117][ T12] kthread+0x318/0x420 [ 53.729781][ T12] ret_from_fork+0x24/0x30 [ 53.734688][ T12] [ 53.734688][ T12] other info that might help us debug this: [ 53.734688][ T12] [ 53.744899][ T12] Possible unsafe locking scenario: [ 53.744899][ T12] [ 53.752321][ T12] CPU0 CPU1 [ 53.757663][ T12] ---- ---- [ 53.763014][ T12] lock(open_disc_mutex); [ 53.767414][ T12] lock(minor_rwsem); [ 53.774055][ T12] lock(open_disc_mutex); [ 53.780958][ T12] lock(minor_rwsem); [ 53.785009][ T12] [ 53.785009][ T12] *** DEADLOCK *** [ 53.785009][ T12] [ 53.793149][ T12] 6 locks held by kworker/0:1/12: [ 53.798160][ T12] #0: 00000000adaad6e0 ((wq_completion)usb_hub_wq){+.+.}, at: process_one_work+0x827/0x1530 [ 53.808643][ T12] #1: 000000004438790c ((work_completion)(&hub->events)){+.+.}, at: process_one_work+0x85b/0x1530 [ 53.819292][ T12] #2: 0000000080269aaa (&dev->mutex){....}, at: hub_event+0x17c/0x3640 [ 53.827596][ T12] #3: 000000009d01872e (&dev->mutex){....}, at: usb_disconnect+0x91/0x8d0 [ 53.836181][ T12] #4: 00000000c7c6ca5e (&dev->mutex){....}, at: device_release_driver_internal+0x23/0x500 [ 53.846655][ T12] #5: 00000000bdce1735 (open_disc_mutex){+.+.}, at: tower_disconnect+0x45/0x300 [ 53.856002][ T12] [ 53.856002][ T12] stack backtrace: [ 53.863085][ T12] CPU: 0 PID: 12 Comm: kworker/0:1 Not tainted 5.3.0-rc7+ #0 [ 53.870451][ T12] Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 [ 53.880599][ T12] Workqueue: usb_hub_wq hub_event [ 53.885638][ T12] Call Trace: [ 53.890402][ T12] dump_stack+0xca/0x13e [ 53.894624][ T12] check_noncircular+0x345/0x3e0 [ 53.899550][ T12] ? print_circular_bug+0x1b0/0x1b0 [ 53.905774][ T12] ? kfree_const+0x51/0x60 [ 53.910453][ T12] ? device_destroy+0x98/0xd0 [ 53.915102][ T12] ? usb_deregister_dev+0x89/0x230 [ 53.920201][ T12] ? tower_disconnect+0xa8/0x300 [ 53.925125][ T12] ? graph_lock+0x80/0x180 [ 53.929531][ T12] ? hlock_class+0x120/0x120 [ 53.934103][ T12] ? mark_lock+0xbc/0x1130 [ 53.938499][ T12] ? debug_check_no_obj_freed+0x20f/0x443 [ 53.944232][ T12] ? find_first_zero_bit+0x94/0xb0 [ 53.949333][ T12] __lock_acquire+0x1f7c/0x3b50 [ 53.954186][ T12] ? mark_held_locks+0x9f/0xe0 [ 53.958937][ T12] ? lockdep_hardirqs_on+0x379/0x580 [ 53.964231][ T12] ? mark_held_locks+0xe0/0xe0 [ 53.969248][ T12] ? lockdep_hardirqs_on+0x379/0x580 [ 53.974557][ T12] lock_acquire+0x127/0x320 [ 53.979066][ T12] ? usb_deregister_dev+0x95/0x230 [ 53.984173][ T12] down_write+0x92/0x150 [ 53.988406][ T12] ? usb_deregister_dev+0x95/0x230 [ 53.994027][ T12] ? __down_timeout+0x2d0/0x2d0 [ 53.998942][ T12] ? root_device_unregister+0x80/0x80 [ 54.004293][ T12] usb_deregister_dev+0x95/0x230 [ 54.009395][ T12] tower_disconnect+0xa8/0x300 [ 54.014137][ T12] usb_unbind_interface+0x1bd/0x8a0 [ 54.019395][ T12] ? usb_autoresume_device+0x60/0x60 [ 54.024667][ T12] device_release_driver_internal+0x42f/0x500 [ 54.030724][ T12] bus_remove_device+0x2dc/0x4a0 [ 54.035643][ T12] device_del+0x420/0xb10 [ 54.039944][ T12] ? __device_links_no_driver+0x240/0x240 [ 54.045637][ T12] ? usb_remove_ep_devs+0x3e/0x80 [ 54.050649][ T12] ? remove_intf_ep_devs+0x13f/0x1d0 [ 54.055907][ T12] usb_disable_device+0x211/0x690 [ 54.060904][ T12] usb_disconnect+0x284/0x8d0 [ 54.065563][ T12] hub_event+0x1454/0x3640 [ 54.069974][ T12] ? find_held_lock+0x2d/0x110 [ 54.074734][ T12] ? mark_held_locks+0xe0/0xe0 [ 54.079498][ T12] ? hub_port_debounce+0x260/0x260 [ 54.084595][ T12] process_one_work+0x92b/0x1530 [ 54.089516][ T12