INIT: Entering runlevel: 2 [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[?25l[?1c7[ ok 8[?25h[?0c. Debian GNU/Linux 7 syzkaller ttyS0 Warning: Permanently added 'ci-upstream-mmots-kasan-gce-2,10.128.0.47' (ECDSA) to the list of known hosts. executing program syzkaller login: [ 17.422852] [ 17.423169] ============================================ [ 17.423913] WARNING: possible recursive locking detected [ 17.424632] 4.14.0-rc5-mm1+ #20 Not tainted [ 17.425203] -------------------------------------------- [ 17.425934] syzkaller119895/2984 is trying to acquire lock: [ 17.426688] (&grp->list_mutex){++++}, at: [] snd_seq_deliver_event+0x553/0x820 [ 17.427872] [ 17.427872] but task is already holding lock: [ 17.428654] (&grp->list_mutex){++++}, at: [] snd_seq_deliver_event+0x553/0x820 [ 17.429833] [ 17.429833] other info that might help us debug this: [ 17.430717] Possible unsafe locking scenario: [ 17.430717] [ 17.431513] CPU0 [ 17.431934] ---- [ 17.432283] lock(&grp->list_mutex); [ 17.432800] lock(&grp->list_mutex); [ 17.433320] [ 17.433320] *** DEADLOCK *** [ 17.433320] [ 17.434144] May be due to missing lock nesting notation [ 17.434144] [ 17.435054] 2 locks held by syzkaller119895/2984: [ 17.435692] #0: (register_mutex#4){+.+.}, at: [] odev_release+0x4a/0x70 [ 17.436807] #1: (&grp->list_mutex){++++}, at: [] snd_seq_deliver_event+0x553/0x820 [ 17.438063] [ 17.438063] stack backtrace: [ 17.439455] CPU: 0 PID: 2984 Comm: syzkaller119895 Not tainted 4.14.0-rc5-mm1+ #20 [ 17.440460] Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 [ 17.441676] Call Trace: [ 17.442037] dump_stack+0x194/0x257 [ 17.442525] ? arch_local_irq_restore+0x53/0x53 [ 17.444387] __lock_acquire+0xed5/0x3d50 [ 17.448415] ? debug_check_no_locks_freed+0x3c0/0x3c0 [ 17.453567] ? debug_check_no_locks_freed+0x3c0/0x3c0 [ 17.458720] ? __lock_acquire+0x6aa/0x3d50 [ 17.462915] ? debug_check_no_locks_freed+0x3c0/0x3c0 [ 17.468066] ? __lock_acquire+0x6aa/0x3d50 [ 17.472265] ? debug_check_no_locks_freed+0x3c0/0x3c0 [ 17.477417] ? __lock_acquire+0x6aa/0x3d50 [ 17.481616] ? graph_lock+0x170/0x170 [ 17.485379] ? hlock_class+0x140/0x140 [ 17.489237] ? check_noncircular+0x20/0x20 [ 17.493435] ? check_noncircular+0x20/0x20 [ 17.497631] ? check_noncircular+0x20/0x20 [ 17.501830] ? print_irqtrace_events+0x270/0x270 [ 17.506551] ? __wake_up_common_lock+0x1c2/0x310 [ 17.511270] lock_acquire+0x1d5/0x580 [ 17.515035] ? lock_acquire+0x1d5/0x580 [ 17.518973] ? snd_seq_deliver_event+0x553/0x820 [ 17.523695] ? lock_release+0xa40/0xa40 [ 17.527635] ? trace_event_raw_event_sched_switch+0x8a0/0x8a0 [ 17.533486] ? rcu_note_context_switch+0x710/0x710 [ 17.538382] ? __might_sleep+0x95/0x190 [ 17.542323] down_read+0x96/0x150 [ 17.545740] ? snd_seq_deliver_event+0x553/0x820 [ 17.550460] ? __down_interruptible+0x6b0/0x6b0 [ 17.555094] ? _raw_read_unlock+0x22/0x30 [ 17.559214] ? snd_seq_port_use_ptr+0x12d/0x1c0 [ 17.563844] snd_seq_deliver_event+0x553/0x820 [ 17.568392] ? do_raw_spin_trylock+0x190/0x190 [ 17.572938] ? snd_seq_deliver_single_event.constprop.11+0x940/0x940 [ 17.579407] ? _raw_spin_unlock_irqrestore+0x31/0xba [ 17.584488] ? trace_hardirqs_on_caller+0x421/0x5c0 [ 17.589475] ? snd_seq_client_use_ptr+0x85/0x330 [ 17.594196] snd_seq_kernel_client_dispatch+0x11e/0x150 [ 17.599524] dummy_input+0x2c4/0x400 [ 17.603200] ? dummy_free+0x20/0x20 [ 17.606793] ? snd_seq_port_use_ptr+0x12d/0x1c0 [ 17.611425] ? dummy_free+0x20/0x20 [ 17.615022] snd_seq_deliver_single_event.constprop.11+0x2fb/0x940 [ 17.621305] ? snd_seq_ioctl_running_mode+0x150/0x150 [ 17.626462] ? snd_seq_timer_get_cur_tick+0xd/0x40 [ 17.631356] ? update_timestamp_of_queue+0x14d/0x200 [ 17.636422] snd_seq_deliver_event+0x362/0x820 [ 17.640969] ? snd_seq_deliver_single_event.constprop.11+0x940/0x940 [ 17.647425] ? trace_hardirqs_on_caller+0x421/0x5c0 [ 17.652406] ? snd_seq_client_use_ptr+0x85/0x330 [ 17.657128] snd_seq_kernel_client_dispatch+0x11e/0x150 [ 17.662455] dummy_input+0x2c4/0x400 [ 17.666133] ? dummy_free+0x20/0x20 [ 17.669725] ? snd_seq_port_use_ptr+0x12d/0x1c0 [ 17.674357] ? dummy_free+0x20/0x20 [ 17.677946] snd_seq_deliver_single_event.constprop.11+0x2fb/0x940 [ 17.684228] ? snd_seq_ioctl_running_mode+0x150/0x150 [ 17.689379] ? snd_seq_client_use_ptr+0x80/0x330 [ 17.694098] snd_seq_deliver_event+0x176/0x820 [ 17.698645] ? do_raw_spin_trylock+0x190/0x190 [ 17.703200] ? snd_seq_deliver_single_event.constprop.11+0x940/0x940 [ 17.709663] ? _raw_spin_unlock_irqrestore+0x31/0xba [ 17.714730] ? trace_hardirqs_on_caller+0x421/0x5c0 [ 17.719715] ? trace_hardirqs_on+0xd/0x10 [ 17.723828] ? snd_seq_client_use_ptr+0x85/0x330 [ 17.728547] snd_seq_kernel_client_dispatch+0x11e/0x150 [ 17.733874] snd_seq_oss_midi_reset+0x44b/0x700 [ 17.738508] ? snd_seq_oss_midi_filemode+0xf0/0xf0 [ 17.743405] snd_seq_oss_synth_reset+0x398/0x980 [ 17.748123] ? locks_remove_file+0x3fa/0x5a0 [ 17.752495] ? snd_seq_oss_synth_cleanup+0x400/0x400 [ 17.757562] ? __fsnotify_parent+0xb4/0x3a0 [ 17.761849] snd_seq_oss_reset+0x6c/0x260 [ 17.765963] ? free_info_entries+0x36/0x36 [ 17.770166] snd_seq_oss_release+0x71/0x120 [ 17.774451] odev_release+0x52/0x70 [ 17.778044] __fput+0x327/0x7e0 [ 17.781288] ? fput+0x140/0x140 [ 17.784531] ? trace_event_raw_event_sched_switch+0x8a0/0x8a0 [ 17.790377] ? _raw_spin_unlock_irq+0x27/0x70 [ 17.794838] ____fput+0x15/0x20 [ 17.798081] task_work_run+0x199/0x270 [ 17.801934] ? task_work_cancel+0x210/0x210 [ 17.806222] ? _raw_spin_unlock+0x22/0x30 [ 17.810335] ? switch_task_namespaces+0x87/0xc0 [ 17.814968] do_exit+0x9b5/0x1ad0 [ 17.818387] ? snd_seq_client_use_ptr+0x85/0x330 [ 17.823107] ? mm_update_next_owner+0x930/0x930 [ 17.827740] ? snd_seq_system_notify+0x11b/0x160 [ 17.832468] ? snd_seq_client_notify_subscription+0x16f/0x210 [ 17.838318] ? snd_seq_dispatch_event+0x5b0/0x5b0 [ 17.843129] ? check_subscription_permission.isra.3+0x11d/0x1d0 [ 17.849153] ? snd_seq_ioctl_subscribe_port+0x1e3/0x2c0 [ 17.854484] ? kasan_check_write+0x14/0x20 [ 17.858684] ? snd_seq_ioctl_unsubscribe_port+0x2c0/0x2c0 [ 17.864184] ? snd_seq_ioctl+0x126/0x400 [ 17.868207] ? snd_seq_open+0x570/0x570 [ 17.872156] ? snd_seq_open+0x570/0x570 [ 17.876094] ? do_vfs_ioctl+0x486/0x1520 [ 17.880119] ? _cond_resched+0x14/0x30 [ 17.883970] ? ioctl_preallocate+0x2b0/0x2b0 [ 17.888345] ? selinux_capable+0x40/0x40 [ 17.892370] ? putname+0xf3/0x130 [ 17.895788] do_group_exit+0x149/0x400 [ 17.899640] ? SyS_exit+0x30/0x30 [ 17.903059] ? trace_hardirqs_on_caller+0x421/0x5c0 [ 17.908038] ? trace_hardirqs_on_thunk+0x1a/0x1c [ 17.912759] SyS_exit_group+0x1d/0x20 [ 17.916525] entry_SYSCALL_64_fastpath+0x1f/0xbe [ 17.921243] RIP: 0033:0x442c58 [ 17.9