[info] Using makefile-style concurrent boot in runlevel 2. [....] Starting enhanced syslogd: rsyslogd[?25l[?1c7[ ok 8[?25h[?0c. [....] Starting periodic command scheduler: cron[?25l[?1c7[ ok 8[?25h[?0c. [....] Starting OpenBSD Secure Shell server: sshd[ 16.002690][ T1673] random: sshd: uninitialized urandom read (32 bytes read) [?25l[?1c7[ ok 8[?25h[?0c. [ 16.225440][ C1] random: crng init done Debian GNU/Linux 7 syzkaller ttyS0 Warning: Permanently added '10.128.1.17' (ECDSA) to the list of known hosts. executing program syzkaller login: [ 41.314655][ T5] usb 1-1: new high-speed USB device number 2 using dummy_hcd [ 41.554609][ T5] usb 1-1: Using ep0 maxpacket: 8 [ 41.674758][ T5] usb 1-1: config 0 has an invalid interface number: 219 but max is 0 [ 41.683158][ T5] usb 1-1: config 0 has no interface number 0 [ 41.689311][ T5] usb 1-1: config 0 interface 219 altsetting 0 endpoint 0xF has an invalid bInterval 0, changing to 7 [ 41.700289][ T5] usb 1-1: config 0 interface 219 altsetting 0 endpoint 0x83 has an invalid bInterval 0, changing to 7 [ 41.711363][ T5] usb 1-1: New USB device found, idVendor=0694, idProduct=0001, bcdDevice=fb.88 [ 41.720414][ T5] usb 1-1: New USB device strings: Mfr=0, Product=0, SerialNumber=0 [ 41.730050][ T5] usb 1-1: config 0 descriptor?? [ 41.995196][ T5] legousbtower 1-1:0.219: LEGO USB Tower firmware version is 129.136 build 65535 [ 42.007110][ T5] legousbtower 1-1:0.219: LEGO USB Tower #-160 now attached to major 180 minor 0 [ 43.294813][ T1728] usb 1-1: LEGO USB Tower reset control request failed [ 43.302526][ T5] usb 1-1: USB disconnect, device number 2 [ 43.312416][ T5] [ 43.314753][ T5] ====================================================== [ 43.321743][ T5] WARNING: possible circular locking dependency detected [ 43.330139][ T5] 5.3.0-rc7+ #0 Not tainted [ 43.334610][ T5] ------------------------------------------------------ [ 43.346721][ T5] kworker/0:0/5 is trying to acquire lock: [ 43.352495][ T5] 00000000cdcd26d1 (minor_rwsem){++++}, at: usb_deregister_dev+0x95/0x230 [ 43.360983][ T5] [ 43.360983][ T5] but task is already holding lock: [ 43.368328][ T5] 00000000d203256d (open_disc_mutex){+.+.}, at: tower_disconnect+0x45/0x300 [ 43.376986][ T5] [ 43.376986][ T5] which lock already depends on the new lock. [ 43.376986][ T5] [ 43.387374][ T5] [ 43.387374][ T5] the existing dependency chain (in reverse order) is: [ 43.396359][ T5] [ 43.396359][ T5] -> #1 (open_disc_mutex){+.+.}: [ 43.403448][ T5] __mutex_lock+0x158/0x1360 [ 43.409497][ T5] tower_open+0xce/0x9b0 [ 43.414252][ T5] usb_open+0x1df/0x270 [ 43.418900][ T5] chrdev_open+0x219/0x5c0 [ 43.423822][ T5] do_dentry_open+0x494/0x1120 [ 43.429093][ T5] path_openat+0x1430/0x3f50 [ 43.434177][ T5] do_filp_open+0x1a1/0x280 [ 43.439172][ T5] do_sys_open+0x3c0/0x580 [ 43.444083][ T5] do_syscall_64+0xb7/0x580 [ 43.449080][ T5] entry_SYSCALL_64_after_hwframe+0x49/0xbe [ 43.455459][ T5] [ 43.455459][ T5] -> #0 (minor_rwsem){++++}: [ 43.462210][ T5] __lock_acquire+0x1f7c/0x3b50 [ 43.467554][ T5] lock_acquire+0x127/0x320 [ 43.472566][ T5] down_write+0x92/0x150 [ 43.477340][ T5] usb_deregister_dev+0x95/0x230 [ 43.482779][ T5] tower_disconnect+0xa8/0x300 [ 43.488033][ T5] usb_unbind_interface+0x1bd/0x8a0 [ 43.493736][ T5] device_release_driver_internal+0x42f/0x500 [ 43.500371][ T5] bus_remove_device+0x2dc/0x4a0 [ 43.505811][ T5] device_del+0x420/0xb10 [ 43.510774][ T5] usb_disable_device+0x211/0x690 [ 43.516300][ T5] usb_disconnect+0x284/0x8d0 [ 43.521484][ T5] hub_event+0x1454/0x3640 [ 43.526586][ T5] process_one_work+0x92b/0x1530 [ 43.532038][ T5] worker_thread+0x96/0xe20 [ 43.537035][ T5] kthread+0x318/0x420 [ 43.541614][ T5] ret_from_fork+0x24/0x30 [ 43.546519][ T5] [ 43.546519][ T5] other info that might help us debug this: [ 43.546519][ T5] [ 43.556730][ T5] Possible unsafe locking scenario: [ 43.556730][ T5] [ 43.564165][ T5] CPU0 CPU1 [ 43.569515][ T5] ---- ---- [ 43.575542][ T5] lock(open_disc_mutex); [ 43.580040][ T5] lock(minor_rwsem); [ 43.586620][ T5] lock(open_disc_mutex); [ 43.593549][ T5] lock(minor_rwsem); [ 43.597601][ T5] [ 43.597601][ T5] *** DEADLOCK *** [ 43.597601][ T5] [ 43.606175][ T5] 6 locks held by kworker/0:0/5: [ 43.611092][ T5] #0: 00000000b1437158 ((wq_completion)usb_hub_wq){+.+.}, at: process_one_work+0x827/0x1530 [ 43.621310][ T5] #1: 00000000a43685f6 ((work_completion)(&hub->events)){+.+.}, at: process_one_work+0x85b/0x1530 [ 43.632043][ T5] #2: 00000000a8372279 (&dev->mutex){....}, at: hub_event+0x17c/0x3640 [ 43.640546][ T5] #3: 00000000ee5d11fc (&dev->mutex){....}, at: usb_disconnect+0x91/0x8d0 [ 43.649352][ T5] #4: 0000000058bc23d0 (&dev->mutex){....}, at: device_release_driver_internal+0x23/0x500 [ 43.659430][ T5] #5: 00000000d203256d (open_disc_mutex){+.+.}, at: tower_disconnect+0x45/0x300 [ 43.668527][ T5] [ 43.668527][ T5] stack backtrace: [ 43.674394][ T5] CPU: 0 PID: 5 Comm: kworker/0:0 Not tainted 5.3.0-rc7+ #0 [ 43.681646][ T5] Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 [ 43.691681][ T5] Workqueue: usb_hub_wq hub_event [ 43.696677][ T5] Call Trace: [ 43.700083][ T5] dump_stack+0xca/0x13e [ 43.704314][ T5] check_noncircular+0x345/0x3e0 [ 43.709249][ T5] ? print_circular_bug+0x1b0/0x1b0 [ 43.714450][ T5] ? kfree_const+0x51/0x60 [ 43.718847][ T5] ? device_destroy+0x98/0xd0 [ 43.723500][ T5] ? usb_deregister_dev+0x89/0x230 [ 43.728695][ T5] ? tower_disconnect+0xa8/0x300 [ 43.733615][ T5] ? graph_lock+0x80/0x180 [ 43.738185][ T5] ? hlock_class+0x120/0x120 [ 43.742746][ T5] ? mark_lock+0xbc/0x1130 [ 43.747161][ T5] ? debug_check_no_obj_freed+0x20f/0x443 [ 43.752852][ T5] ? find_first_zero_bit+0x94/0xb0 [ 43.757950][ T5] __lock_acquire+0x1f7c/0x3b50 [ 43.762782][ T5] ? mark_held_locks+0x9f/0xe0 [ 43.767527][ T5] ? lockdep_hardirqs_on+0x379/0x580 [ 43.772793][ T5] ? mark_held_locks+0xe0/0xe0 [ 43.777541][ T5] ? lockdep_hardirqs_on+0x379/0x580 [ 43.782806][ T5] lock_acquire+0x127/0x320 [ 43.787295][ T5] ? usb_deregister_dev+0x95/0x230 [ 43.792393][ T5] down_write+0x92/0x150 [ 43.796623][ T5] ? usb_deregister_dev+0x95/0x230 [ 43.801732][ T5] ? __down_timeout+0x2d0/0x2d0 [ 43.806561][ T5] ? root_device_unregister+0x80/0x80 [ 43.811994][ T5] usb_deregister_dev+0x95/0x230 [ 43.817010][ T5] tower_disconnect+0xa8/0x300 [ 43.822701][ T5] usb_unbind_interface+0x1bd/0x8a0 [ 43.827916][ T5] ? usb_autoresume_device+0x60/0x60 [ 43.833196][ T5] device_release_driver_internal+0x42f/0x500 [ 43.839237][ T5] bus_remove_device+0x2dc/0x4a0 [ 43.844163][ T5] device_del+0x420/0xb10 [ 43.848465][ T5] ? __device_links_no_driver+0x240/0x240 [ 43.854159][ T5] ? usb_remove_ep_devs+0x3e/0x80 [ 43.859178][ T5] ? remove_intf_ep_devs+0x13f/0x1d0 [ 43.864450][ T5] usb_disable_device+0x211/0x690 [ 43.869464][ T5] usb_disconnect+0x284/0x8d0 [ 43.874129][ T5] hub_event+0x1454/0x3640 [ 43.878806][ T5] ? find_held_lock+0x2d/0x110 [ 43.883545][ T5] ? mark_held_locks+0xe0/0xe0 [ 43.888281][ T5] ? hub_port_debounce+0x260/0x260 [ 43.893374][ T5] process_one_work+0x92b/0x1530