[ OK ] Reached target Login Prompts. [ OK ] Reached target Multi-User System. [ OK ] Reached target Graphical Interface. Starting Update UTMP about System Runlevel Changes... [ OK ] Started Update UTMP about System Runlevel Changes. Debian GNU/Linux 9 syzkaller ttyS0 Warning: Permanently added '10.128.1.35' (ECDSA) to the list of known hosts. executing program syzkaller login: [ 55.441478][ T6802] IPVS: ftp: loaded support on port[0] = 21 [ 55.755832][ T2700] usb 1-1: new high-speed USB device number 2 using dummy_hcd [ 55.995769][ T2700] usb 1-1: Using ep0 maxpacket: 8 [ 56.115864][ T2700] usb 1-1: config 0 has an invalid descriptor of length 0, skipping remainder of the config [ 56.126124][ T2700] usb 1-1: New USB device found, idVendor=0bd3, idProduct=0555, bcdDevice=69.6a [ 56.135164][ T2700] usb 1-1: New USB device strings: Mfr=0, Product=0, SerialNumber=0 [ 56.149454][ T2700] usb 1-1: config 0 descriptor?? [ 56.190409][ T2700] uvcvideo: Found UVC 0.00 device (0bd3:0555) [ 56.198097][ T2700] uvcvideo 1-1:0.0: Entity type for entity Output 1 was not initialized! [ 56.207298][ T2700] uvcvideo 1-1:0.0: Entity type for entity Input 255 was not initialized! [ 56.390094][ T28] usb 1-1: USB disconnect, device number 2 [ 56.409943][ T28] [ 56.412302][ T28] ============================================ [ 56.418528][ T28] WARNING: possible recursive locking detected [ 56.424680][ T28] 5.7.0-rc6-next-20200522-syzkaller #0 Not tainted [ 56.431165][ T28] -------------------------------------------- [ 56.437295][ T28] kworker/1:1/28 is trying to acquire lock: [ 56.443154][ T28] ffffffff8a4f3aa8 (media_devnode_lock){+.+.}-{3:3}, at: media_devnode_release+0x1a/0xe0 [ 56.452946][ T28] [ 56.452946][ T28] but task is already holding lock: [ 56.460288][ T28] ffffffff8a4f3aa8 (media_devnode_lock){+.+.}-{3:3}, at: media_devnode_unregister+0x1c/0x69 [ 56.470341][ T28] [ 56.470341][ T28] other info that might help us debug this: [ 56.478368][ T28] Possible unsafe locking scenario: [ 56.478368][ T28] [ 56.485787][ T28] CPU0 [ 56.489039][ T28] ---- [ 56.492288][ T28] lock(media_devnode_lock); [ 56.496931][ T28] lock(media_devnode_lock); [ 56.501574][ T28] [ 56.501574][ T28] *** DEADLOCK *** [ 56.501574][ T28] [ 56.509702][ T28] May be due to missing lock nesting notation [ 56.509702][ T28] [ 56.518176][ T28] 6 locks held by kworker/1:1/28: [ 56.523249][ T28] #0: ffff88821a8e6138 ((wq_completion)usb_hub_wq){+.+.}-{0:0}, at: process_one_work+0x844/0x16a0 [ 56.533907][ T28] #1: ffffc90000de7dc0 ((work_completion)(&hub->events)){+.+.}-{0:0}, at: process_one_work+0x878/0x16a0 [ 56.545112][ T28] #2: ffff88809e850218 (&dev->mutex){....}-{3:3}, at: hub_event+0x1b6/0x38f0 [ 56.553945][ T28] #3: ffff88809749e218 (&dev->mutex){....}-{3:3}, at: usb_disconnect+0x91/0x8d0 [ 56.563068][ T28] #4: ffff8880951c01a8 (&dev->mutex){....}-{3:3}, at: device_release_driver_internal+0x23/0x500 [ 56.573545][ T28] #5: ffffffff8a4f3aa8 (media_devnode_lock){+.+.}-{3:3}, at: media_devnode_unregister+0x1c/0x69 [ 56.584036][ T28] [ 56.584036][ T28] stack backtrace: [ 56.589902][ T28] CPU: 1 PID: 28 Comm: kworker/1:1 Not tainted 5.7.0-rc6-next-20200522-syzkaller #0 [ 56.600193][ T28] Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 [ 56.610227][ T28] Workqueue: usb_hub_wq hub_event [ 56.615219][ T28] Call Trace: [ 56.618484][ T28] dump_stack+0x18f/0x20d [ 56.622804][ T28] __lock_acquire.cold+0x240/0x3e2 [ 56.627901][ T28] ? stack_trace_consume_entry+0x160/0x160 [ 56.633704][ T28] ? print_circular_bug.isra.0+0x3a0/0x3a0 [ 56.639501][ T28] ? lockdep_hardirqs_on_prepare+0x590/0x590 [ 56.645466][ T28] ? mark_lock+0x11f/0xdd0 [ 56.649869][ T28] ? save_trace+0x42/0xaf0 [ 56.654270][ T28] lock_acquire+0x1f2/0x8f0 [ 56.658769][ T28] ? media_devnode_release+0x1a/0xe0 [ 56.664024][ T28] ? lock_release+0x800/0x800 [ 56.668676][ T28] __mutex_lock+0x156/0x13c0 [ 56.673324][ T28] ? media_devnode_release+0x1a/0xe0 [ 56.678580][ T28] ? mark_held_locks+0x9f/0xe0 [ 56.683323][ T28] ? media_devnode_release+0x1a/0xe0 [ 56.688579][ T28] ? lockdep_hardirqs_on_prepare+0x3a2/0x590 [ 56.694528][ T28] ? mutex_trylock+0x2c0/0x2c0 [ 56.699261][ T28] ? _raw_spin_unlock_irqrestore+0x9b/0xe0 [ 56.705050][ T28] ? release_nodes+0x4cb/0x910 [ 56.709783][ T28] ? devres_remove_group+0x440/0x440 [ 56.715052][ T28] ? media_devnode_release+0x1a/0xe0 [ 56.720306][ T28] media_devnode_release+0x1a/0xe0 [ 56.725388][ T28] ? media_write+0x1c0/0x1c0 [ 56.729948][ T28] device_release+0x71/0x200 [ 56.734507][ T28] ? dev_attr_show+0x90/0x90 [ 56.739069][ T28] kobject_put+0x1c8/0x2f0 [ 56.743472][ T28] cdev_device_del+0x69/0x80 [ 56.748041][ T28] media_devnode_unregister+0x2b/0x69 [ 56.753385][ T28] media_device_unregister+0x3da/0x570 [ 56.758816][ T28] uvc_unregister_video+0x1b6/0x210 [ 56.763985][ T28] uvc_disconnect+0xbc/0x160 [ 56.768547][ T28] usb_unbind_interface+0x1bd/0x8a0 [ 56.773716][ T28] ? __pm_runtime_idle+0xd1/0x320 [ 56.778719][ T28] ? usb_autoresume_device+0x60/0x60 [ 56.783985][ T28] device_release_driver_internal+0x432/0x500 [ 56.790022][ T28] bus_remove_device+0x2dc/0x4a0 [ 56.794929][ T28] device_del+0x481/0xd30 [ 56.799231][ T28] ? lockdep_hardirqs_on_prepare+0x3a2/0x590 [ 56.805181][ T28] ? device_link_add_missing_supplier_links+0x370/0x370 [ 56.812082][ T28] ? remove_intf_ep_devs+0x13f/0x1d0 [ 56.817338][ T28] usb_disable_device+0x211/0x690 [ 56.822333][ T28] usb_disconnect+0x284/0x8d0 [ 56.826982][ T28] hub_event+0x17ca/0x38f0 [ 56.831387][ T28] ? hub_port_debounce+0x260/0x260 [ 56.836492][ T28] ? usermodehelper_read_trylock+0xf0/0x2d0 [ 56.842355][ T28] ? debug_smp_processor_id+0x2f/0x185 [ 56.847784][ T28] ? rcu_read_lock_sched_held+0x9c/0xd0 [ 56.853299][ T28] ? rcu_read_lock_any_held.part.0+0x50/0x50 [ 56.859275][ T28] process_one_work+0x965/0x16a0 [ 56.864183][ T28] ? lock_release+0x800/0x800 [ 56.868851][ T28] ? pwq_dec_nr_in_flight+0x310/0x310 [ 56.874193][ T28] ? rwlock_bug.part.0+0x90/0x90 [ 56.879103][ T28] worker_thread+0x96/0xe20 [ 56.883592][ T28] ? process_one_work+0x16a0/0x16a0 [ 56.888762][ T28] kthread+0x3b5/0x4a0 [ 56.892800][ T28] ? kthread_mod_delayed_work+0x1a0/0x1a0 [ 56.898833][ T28] ? kthread_mod_delayed_work+0x1a0/0x1a0 [ 56.904610][ T28] ret_from_fork+0x24/0x30