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-kasan-gce-0,10.128.0.24' (ECDSA) to the list of known hosts. executing program syzkaller login: [ 41.422117] [ 41.423792] ============================================ [ 41.429203] WARNING: possible recursive locking detected [ 41.434618] 4.14.0-rc1+ #88 Not tainted [ 41.438556] -------------------------------------------- [ 41.443969] syzkaller883997/2981 is trying to acquire lock: [ 41.449641] (&grp->list_mutex){++++}, at: [] snd_seq_deliver_event+0x279/0x790 [ 41.458624] [ 41.458624] but task is already holding lock: [ 41.464557] (&grp->list_mutex){++++}, at: [] snd_seq_deliver_event+0x279/0x790 [ 41.473533] [ 41.473533] other info that might help us debug this: [ 41.480159] Possible unsafe locking scenario: [ 41.480159] [ 41.486179] CPU0 [ 41.488724] ---- [ 41.491271] lock(&grp->list_mutex); [ 41.495034] lock(&grp->list_mutex); [ 41.498797] [ 41.498797] *** DEADLOCK *** [ 41.498797] [ 41.504818] May be due to missing lock nesting notation [ 41.504818] [ 41.511718] 2 locks held by syzkaller883997/2981: [ 41.516521] #0: (register_mutex#4){+.+.}, at: [] odev_release+0x4a/0x70 [ 41.524980] #1: (&grp->list_mutex){++++}, at: [] snd_seq_deliver_event+0x279/0x790 [ 41.534391] [ 41.534391] stack backtrace: [ 41.538851] CPU: 1 PID: 2981 Comm: syzkaller883997 Not tainted 4.14.0-rc1+ #88 [ 41.546172] Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 [ 41.555492] Call Trace: [ 41.558047] dump_stack+0x194/0x257 [ 41.561640] ? arch_local_irq_restore+0x53/0x53 [ 41.566278] __lock_acquire+0x1232/0x4620 [ 41.570393] ? debug_check_no_locks_freed+0x3d0/0x3d0 [ 41.575548] ? debug_check_no_locks_freed+0x3d0/0x3d0 [ 41.580705] ? snd_seq_deliver_event+0x318/0x790 [ 41.585428] ? save_stack_trace+0x16/0x20 [ 41.589542] ? __lock_acquire+0x20fd/0x4620 [ 41.593829] ? unwind_get_return_address+0x61/0xa0 [ 41.598720] ? __save_stack_trace+0x61/0xd0 [ 41.603007] ? debug_check_no_locks_freed+0x3d0/0x3d0 [ 41.608159] ? __lock_acquire+0x732/0x4620 [ 41.612358] ? snd_seq_deliver_event+0x12c/0x790 [ 41.617078] ? save_stack_trace+0x16/0x20 [ 41.621193] ? debug_check_no_locks_freed+0x3d0/0x3d0 [ 41.626351] ? check_noncircular+0x20/0x20 [ 41.630549] ? debug_check_no_locks_freed+0x3d0/0x3d0 [ 41.635704] ? debug_check_no_locks_freed+0x3d0/0x3d0 [ 41.640858] ? check_noncircular+0x20/0x20 [ 41.645060] ? save_stack_trace+0x16/0x20 [ 41.649186] ? __lock_acquire+0x20fd/0x4620 [ 41.653478] ? find_held_lock+0x39/0x1d0 [ 41.657507] lock_acquire+0x1d5/0x580 [ 41.661274] ? snd_seq_deliver_event+0x279/0x790 [ 41.665995] ? lock_release+0xd70/0xd70 [ 41.669934] ? check_same_owner+0x320/0x320 [ 41.674218] ? lock_release+0xd70/0xd70 [ 41.678157] ? __might_sleep+0x95/0x190 [ 41.682099] down_read+0x96/0x150 [ 41.686079] ? snd_seq_deliver_event+0x279/0x790 [ 41.690803] ? __down_interruptible+0x6a0/0x6a0 [ 41.695439] ? _raw_read_unlock+0x22/0x30 [ 41.699553] ? snd_seq_port_use_ptr+0x12d/0x1c0 [ 41.704190] snd_seq_deliver_event+0x279/0x790 [ 41.708742] ? do_raw_spin_trylock+0x190/0x190 [ 41.713299] ? snd_seq_deliver_single_event.constprop.11+0x940/0x940 [ 41.719763] ? _raw_spin_unlock_irqrestore+0x31/0xba [ 41.724840] ? trace_hardirqs_on_caller+0x421/0x5c0 [ 41.729825] ? snd_seq_client_use_ptr+0x85/0x330 [ 41.734548] snd_seq_kernel_client_dispatch+0x11e/0x150 [ 41.739878] dummy_input+0x2c4/0x400 [ 41.743557] ? dummy_free+0x20/0x20 [ 41.747149] ? snd_seq_port_use_ptr+0x12d/0x1c0 [ 41.751783] ? dummy_free+0x20/0x20 [ 41.755375] snd_seq_deliver_single_event.constprop.11+0x2fb/0x940 [ 41.761656] ? snd_seq_ioctl_running_mode+0x150/0x150 [ 41.766809] ? queueptr+0x88/0xa0 [ 41.770229] ? update_timestamp_of_queue+0x14d/0x200 [ 41.775297] snd_seq_deliver_event+0x318/0x790 [ 41.779852] ? snd_seq_deliver_single_event.constprop.11+0x940/0x940 [ 41.786314] ? trace_hardirqs_on_caller+0x421/0x5c0 [ 41.791296] ? snd_seq_client_use_ptr+0x85/0x330 [ 41.796017] snd_seq_kernel_client_dispatch+0x11e/0x150 [ 41.801347] dummy_input+0x2c4/0x400 [ 41.805024] ? dummy_free+0x20/0x20 [ 41.808617] ? snd_seq_port_use_ptr+0x12d/0x1c0 [ 41.813248] ? dummy_free+0x20/0x20 [ 41.816838] snd_seq_deliver_single_event.constprop.11+0x2fb/0x940 [ 41.823119] ? snd_seq_ioctl_running_mode+0x150/0x150 [ 41.828273] ? snd_seq_client_use_ptr+0x3c/0x330 [ 41.832994] snd_seq_deliver_event+0x12c/0x790 [ 41.837542] ? do_raw_spin_trylock+0x190/0x190 [ 41.842091] ? snd_seq_deliver_single_event.constprop.11+0x940/0x940 [ 41.848550] ? _raw_spin_unlock_irqrestore+0x31/0xba [ 41.853618] ? trace_hardirqs_on_caller+0x421/0x5c0 [ 41.858599] ? trace_hardirqs_on+0xd/0x10 [ 41.862712] ? snd_seq_client_use_ptr+0x85/0x330 [ 41.867433] snd_seq_kernel_client_dispatch+0x11e/0x150 [ 41.872762] snd_seq_oss_midi_reset+0x44b/0x700 [ 41.877398] ? snd_seq_oss_midi_filemode+0xf0/0xf0 [ 41.882293] ? depot_save_stack+0x12c/0x490 [ 41.886583] snd_seq_oss_synth_reset+0x398/0x980 [ 41.891308] ? locks_remove_file+0x3fa/0x5a0 [ 41.895682] ? snd_seq_oss_synth_cleanup+0x400/0x400 [ 41.900750] ? __fsnotify_parent+0xb4/0x3a0 [ 41.905036] snd_seq_oss_reset+0x6c/0x260 [ 41.909149] ? free_info_entries+0x36/0x36 [ 41.913347] snd_seq_oss_release+0x71/0x120 [ 41.917633] odev_release+0x52/0x70 [ 41.921228] __fput+0x333/0x7f0 [ 41.924474] ? fput+0x140/0x140 [ 41.927719] ? _raw_spin_unlock_irq+0x27/0x70 [ 41.932177] ____fput+0x15/0x20 [ 41.935423] task_work_run+0x199/0x270 [ 41.939275] ? task_work_cancel+0x210/0x210 [ 41.943559] ? _raw_spin_unlock+0x22/0x30 [ 41.947673] ? switch_task_namespaces+0x87/0xc0 [ 41.952309] do_exit+0xa52/0x1b40 [ 41.955727] ? unwind_dump+0x4c0/0x4c0 [ 41.959582] ? mm_update_next_owner+0x930/0x930 [ 41.964213] ? __kernel_text_address+0xae/0xe0 [ 41.968758] ? unwind_get_return_address+0x61/0xa0 [ 41.973651] ? __save_stack_trace+0x7e/0xd0 [ 41.977937] ? depot_save_stack+0x12c/0x490 [ 41.982225] ? putname+0xee/0x130 [ 41.985646] ? save_stack+0xa3/0xd0 [ 41.989237] ? save_stack_trace+0x16/0x20 [ 41.993349] ? save_stack+0x43/0xd0 [ 41.996941] ? kasan_slab_free+0x71/0xc0 [ 42.000965] ? kmem_cache_free+0x77/0x280 [ 42.005078] ? putname+0xee/0x130 [ 42.008500] ? do_sys_open+0x31b/0x6d0 [ 42.012351] ? SyS_openat+0x30/0x40 [ 42.015944] ? entry_SYSCALL_64_fastpath+0x1f/0xbe [ 42.020838] ? __lock_is_held+0xbc/0x140 [ 42.024867] ? __fd_install+0x2f7/0x6a0 [ 42.028807] ? get_unused_fd_flags+0x190/0x190 [ 42.033358] ? rcu_pm_notify+0xc0/0xc0 [ 42.037213] ? putname+0xee/0x130 [ 42.040629] ? rcu_read_lock_sched_held+0x108/0x120 [ 42.045611] ? kmem_cache_free+0x249/0x280 [ 42.049810] ? putname+0xf3/0x130 [ 42.053230] do_group_exit+0x149/0x400 [ 42.057083] ? filp_open+0x70/0x70 [ 42.060587] ? SyS_exit+0x30/0x30 [ 42.064004] ? trace_hardirqs_on_caller+0x421/0x5c0 [ 42.068986] ? trace_hardirqs_on_thunk+0x1a/0x1c [ 42.073710] SyS_exit_group+0x1d/0x20 [ 42.077477] entry_SYSCALL_64_fastpath+0x1f/0xbe [ 42.082196] RIP: 0033:0x442c58 [ 42.085351] RSP: 002b:00007ffd15d4f8d8 EFLAGS: 00000246 ORIG_RAX: 00000000000000e7 [ 42.093023] RAX: ffffffffffffffda RBX: 0000000000000000 RCX: 0000000000442c58 [ 42.100270] RDX: 0000000000000000 RSI: 000000000000003c RDI: 0000000000000000 [ 42.107504] RBP: 0000000000000082 R08: 00000000000000e7 R09: ffffffffffffffd0 [ 42.114739] R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000401ca0 [ 42.121974] R13: 0000000000401d30 R14