INIT: Entering runlevel: 2 [[36minfo[39;49m] Using makefile-style concurrent boot in runlevel 2. [....] Starting enhanced syslogd: rsyslogd[?25l[?1c7[1G[[32m ok [39;49m8[?25h[?0c. [....] Starting periodic command scheduler: cron[?25l[?1c7[1G[[32m ok [39;49m8[?25h[?0c. [....] Starting OpenBSD Secure Shell server: sshd[?25l[?1c7[1G[[32m ok [39;49m8[?25h[?0c. Debian GNU/Linux 7 syzkaller ttyS0 Warning: Permanently added 'ci-android-49-kasan-gce-0,10.128.15.211' (ECDSA) to the list of known hosts. executing program syzkaller login: [ 43.709132] [ 43.709478] ============================================= [ 43.710207] [ INFO: possible recursive locking detected ] [ 43.710966] 4.9.60-gdfe0a9b #81 Not tainted [ 43.711555] --------------------------------------------- [ 43.712283] syzkaller633487/3245 is trying to acquire lock: [ 43.713049] (&grp->list_mutex){++++.+}, at: [] snd_seq_deliver_event+0x4cf/0x740 [ 43.714400] but task is already holding lock: [ 43.715016] (&grp->list_mutex){++++.+}, at: [] snd_seq_deliver_event+0x4cf/0x740 [ 43.716326] other info that might help us debug this: [ 43.717033] Possible unsafe locking scenario: [ 43.717033] [ 43.717828] CPU0 [ 43.718266] ---- [ 43.718656] lock(&grp->list_mutex); [ 43.719239] lock(&grp->list_mutex); [ 43.719838] [ 43.719838] *** DEADLOCK *** [ 43.719838] [ 43.720667] May be due to missing lock nesting notation [ 43.720667] [ 43.721633] 2 locks held by syzkaller633487/3245: [ 43.722427] #0: (register_mutex#4){+.+.+.}, at: [] odev_release+0x4a/0x70 [ 43.723764] #1: (&grp->list_mutex){++++.+}, at: [] snd_seq_deliver_event+0x4cf/0x740 [ 43.725190] [ 43.725190] stack backtrace: [ 43.725806] CPU: 0 PID: 3245 Comm: syzkaller633487 Not tainted 4.9.60-gdfe0a9b #81 [ 43.726830] Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 [ 43.728051] ffff8801c772f100 ffffffff81d91389 ffffffff8537b4d0 ffffffff8537b4d0 [ 43.729185] dffffc0000000000 f75f28fb6e9d5274 0000000000000000 ffff8801c772f2c8 [ 43.736777] ffffffff8123c925 ffff8801c7720000 ffff8801c7720928 00000000000003c7 [ 43.744724] Call Trace: [ 43.747277] [] dump_stack+0xc1/0x128 [ 43.752608] [] __lock_acquire+0xe35/0x3640 [ 43.758460] [] ? debug_check_no_locks_freed+0x2c0/0x2c0 [ 43.765439] [] ? debug_check_no_locks_freed+0x2c0/0x2c0 [ 43.772421] [] ? __lock_is_held+0xa1/0xf0 [ 43.778187] [] lock_acquire+0x12e/0x410 [ 43.783776] [] ? snd_seq_deliver_event+0x4cf/0x740 [ 43.790323] [] down_read+0x44/0xb0 [ 43.795478] [] ? snd_seq_deliver_event+0x4cf/0x740 [ 43.802022] [] snd_seq_deliver_event+0x4cf/0x740 [ 43.808407] [] ? snd_seq_deliver_single_event.constprop.11+0x7c0/0x7c0 [ 43.816688] [] ? _raw_spin_unlock_irqrestore+0x45/0x70 [ 43.823578] [] snd_seq_kernel_client_dispatch+0x11e/0x150 [ 43.830728] [] dummy_input+0x235/0x320 [ 43.836230] [] ? dummy_free+0x20/0x20 [ 43.841643] [] ? _raw_read_unlock+0x2c/0x50 [ 43.847576] [] ? snd_seq_port_use_ptr+0x12d/0x1c0 [ 43.854030] [] ? dummy_free+0x20/0x20 [ 43.859444] [] snd_seq_deliver_single_event.constprop.11+0x310/0x7c0 [ 43.867548] [] ? _raw_spin_unlock_irqrestore+0x5a/0x70 [ 43.874439] [] ? snd_seq_ioctl_running_mode+0x150/0x150 [ 43.881416] [] ? _raw_spin_unlock_irqrestore+0x45/0x70 [ 43.888314] [] ? snd_seq_timer_get_cur_tick+0xd/0x40 [ 43.895029] [] ? update_timestamp_of_queue+0x14d/0x200 [ 43.901918] [] snd_seq_deliver_event+0x316/0x740 [ 43.908296] [] ? snd_seq_deliver_single_event.constprop.11+0x7c0/0x7c0 [ 43.916574] [] ? _raw_spin_unlock_irqrestore+0x45/0x70 [ 43.923463] [] snd_seq_kernel_client_dispatch+0x11e/0x150 [ 43.930613] [] dummy_input+0x235/0x320 [ 43.936116] [] ? dummy_free+0x20/0x20 [ 43.941530] [] ? _raw_read_unlock+0x2c/0x50 [ 43.947462] [] ? snd_seq_port_use_ptr+0x12d/0x1c0 [ 43.953916] [] ? dummy_free+0x20/0x20 [ 43.959340] [] snd_seq_deliver_single_event.constprop.11+0x310/0x7c0 [ 43.967452] [] ? snd_seq_ioctl_running_mode+0x150/0x150 [ 43.974978] [] ? debug_check_no_locks_freed+0x2c0/0x2c0 [ 43.981960] [] ? update_stack_state.constprop.5+0xca/0x150 [ 43.989197] [] snd_seq_deliver_event+0x12d/0x740 [ 43.995569] [] ? mark_held_locks+0xaf/0x100 [ 44.001503] [] ? snd_seq_deliver_single_event.constprop.11+0x7c0/0x7c0 [ 44.009781] [] ? trace_hardirqs_on_caller+0x38b/0x590 [ 44.016587] [] ? _raw_spin_unlock_irqrestore+0x45/0x70 [ 44.023476] [] snd_seq_kernel_client_dispatch+0x11e/0x150 [ 44.030638] [] snd_seq_oss_midi_reset+0x390/0x570 [ 44.037104] [] ? snd_seq_oss_midi_filemode+0xf0/0xf0 [ 44.043820] [] ? mark_held_locks+0xaf/0x100 [ 44.049755] [] snd_seq_oss_synth_reset+0x3c0/0x8b0 [ 44.056300] [] ? trace_hardirqs_on_caller+0x38b/0x590 [ 44.063103] [] ? snd_seq_oss_synth_cleanup+0x400/0x400 [ 44.069994] [] ? check_preemption_disabled+0x3b/0x200 [ 44.076798] [] ? mutex_lock_killable_nested+0x960/0x960 [ 44.083789] [] ? fsnotify+0x86/0xf30 [ 44.089118] [] ? snd_midi_event_new+0x200/0x200 [ 44.095400] [] snd_seq_oss_reset+0x6c/0x260 [ 44.101336] [] ? snd_midi_event_new+0x200/0x200 [ 44.107616] [] snd_seq_oss_release+0x71/0x130 [ 44.113731] [] odev_release+0x52/0x70 [ 44.119144] [] __fput+0x28c/0x6e0 [ 44.124210] [] ____fput+0x15/0x20 [ 44.129279] [] task_work_run+0x115/0x190 [ 44.134954] [] do_exit+0x7e7/0x2a40 [ 44.140200] [] ? selinux_file_ioctl+0x355/0x530 [ 44.146481] [] ? release_task+0x1240/0x1240 [ 44.152414] [] ? up_read+0x1a/0x40 [ 44.157569] [] ? _