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-next-kasan-gce-2,10.128.0.51' (ECDSA) to the list of known hosts. executing program syzkaller login: [ 41.750648] [ 41.752325] ============================================ [ 41.757736] WARNING: possible recursive locking detected [ 41.763148] 4.13.0-next-20170915+ #23 Not tainted [ 41.767950] -------------------------------------------- [ 41.773362] syzkaller215791/2982 is trying to acquire lock: [ 41.779045] (&grp->list_mutex){++++}, at: [] snd_seq_deliver_event+0x279/0x790 [ 41.788030] [ 41.788030] but task is already holding lock: [ 41.793962] (&grp->list_mutex){++++}, at: [] snd_seq_deliver_event+0x279/0x790 [ 41.802938] [ 41.802938] other info that might help us debug this: [ 41.809565] Possible unsafe locking scenario: [ 41.809565] [ 41.815585] CPU0 [ 41.818130] ---- [ 41.820676] lock(&grp->list_mutex); [ 41.824440] lock(&grp->list_mutex); [ 41.828210] [ 41.828210] *** DEADLOCK *** [ 41.828210] [ 41.834231] May be due to missing lock nesting notation [ 41.834231] [ 41.841124] 2 locks held by syzkaller215791/2982: [ 41.845927] #0: (register_mutex#4){+.+.}, at: [] odev_release+0x4a/0x70 [ 41.854390] #1: (&grp->list_mutex){++++}, at: [] snd_seq_deliver_event+0x279/0x790 [ 41.863799] [ 41.863799] stack backtrace: [ 41.868268] CPU: 1 PID: 2982 Comm: syzkaller215791 Not tainted 4.13.0-next-20170915+ #23 [ 41.876458] Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 [ 41.885774] Call Trace: [ 41.888330] dump_stack+0x194/0x257 [ 41.891922] ? arch_local_irq_restore+0x53/0x53 [ 41.896560] __lock_acquire+0x1232/0x4620 [ 41.900689] ? debug_check_no_locks_freed+0x3d0/0x3d0 [ 41.905843] ? debug_check_no_locks_freed+0x3d0/0x3d0 [ 41.910994] ? snd_seq_deliver_event+0x318/0x790 [ 41.915713] ? save_stack_trace+0x16/0x20 [ 41.919824] ? __lock_acquire+0x20fd/0x4620 [ 41.924110] ? unwind_get_return_address+0x61/0xa0 [ 41.929022] ? __save_stack_trace+0x61/0xd0 [ 41.933308] ? debug_check_no_locks_freed+0x3d0/0x3d0 [ 41.938461] ? __lock_acquire+0x732/0x4620 [ 41.942659] ? snd_seq_deliver_event+0x12c/0x790 [ 41.947377] ? save_stack_trace+0x16/0x20 [ 41.951490] ? debug_check_no_locks_freed+0x3d0/0x3d0 [ 41.956644] ? check_noncircular+0x20/0x20 [ 41.960840] ? debug_check_no_locks_freed+0x3d0/0x3d0 [ 41.965992] ? debug_check_no_locks_freed+0x3d0/0x3d0 [ 41.971143] ? check_noncircular+0x20/0x20 [ 41.975340] ? __lock_acquire+0x20fd/0x4620 [ 41.979624] ? find_held_lock+0x39/0x1d0 [ 41.983652] lock_acquire+0x1d5/0x580 [ 41.987414] ? snd_seq_deliver_event+0x279/0x790 [ 41.992133] ? lock_release+0xd70/0xd70 [ 41.996072] ? check_same_owner+0x320/0x320 [ 42.000357] ? lock_release+0xd70/0xd70 [ 42.004296] ? __might_sleep+0x95/0x190 [ 42.008236] down_read+0x96/0x150 [ 42.011661] ? snd_seq_deliver_event+0x279/0x790 [ 42.016380] ? __down_interruptible+0x6a0/0x6a0 [ 42.021012] ? _raw_read_unlock+0x22/0x30 [ 42.025123] ? snd_seq_port_use_ptr+0x12d/0x1c0 [ 42.029755] snd_seq_deliver_event+0x279/0x790 [ 42.034302] ? do_raw_spin_trylock+0x190/0x190 [ 42.038850] ? snd_seq_deliver_single_event.constprop.11+0x940/0x940 [ 42.045313] ? _raw_spin_unlock_irqrestore+0x31/0xba [ 42.050378] ? trace_hardirqs_on_caller+0x421/0x5c0 [ 42.055358] ? snd_seq_client_use_ptr+0x85/0x330 [ 42.060077] snd_seq_kernel_client_dispatch+0x11e/0x150 [ 42.065405] dummy_input+0x2c4/0x400 [ 42.069091] ? dummy_free+0x20/0x20 [ 42.072684] ? snd_seq_port_use_ptr+0x12d/0x1c0 [ 42.077315] ? dummy_free+0x20/0x20 [ 42.080906] snd_seq_deliver_single_event.constprop.11+0x2fb/0x940 [ 42.087187] ? snd_seq_ioctl_running_mode+0x150/0x150 [ 42.092342] ? queueptr+0x88/0xa0 [ 42.095759] ? update_timestamp_of_queue+0x14d/0x200 [ 42.100826] snd_seq_deliver_event+0x318/0x790 [ 42.105374] ? snd_seq_deliver_single_event.constprop.11+0x940/0x940 [ 42.111828] ? trace_hardirqs_on_caller+0x421/0x5c0 [ 42.116808] ? snd_seq_client_use_ptr+0x85/0x330 [ 42.121539] snd_seq_kernel_client_dispatch+0x11e/0x150 [ 42.126866] dummy_input+0x2c4/0x400 [ 42.130545] ? dummy_free+0x20/0x20 [ 42.134137] ? snd_seq_port_use_ptr+0x12d/0x1c0 [ 42.138769] ? dummy_free+0x20/0x20 [ 42.142359] snd_seq_deliver_single_event.constprop.11+0x2fb/0x940 [ 42.148642] ? snd_seq_ioctl_running_mode+0x150/0x150 [ 42.153796] ? snd_seq_client_use_ptr+0x3c/0x330 [ 42.158515] snd_seq_deliver_event+0x12c/0x790 [ 42.163059] ? do_raw_spin_trylock+0x190/0x190 [ 42.167604] ? snd_seq_deliver_single_event.constprop.11+0x940/0x940 [ 42.174059] ? _raw_spin_unlock_irqrestore+0x31/0xba [ 42.179126] ? trace_hardirqs_on_caller+0x421/0x5c0 [ 42.184104] ? trace_hardirqs_on+0xd/0x10 [ 42.188216] ? snd_seq_client_use_ptr+0x85/0x330 [ 42.192947] snd_seq_kernel_client_dispatch+0x11e/0x150 [ 42.198272] snd_seq_oss_midi_reset+0x44b/0x700 [ 42.202906] ? snd_seq_oss_midi_filemode+0xf0/0xf0 [ 42.207799] ? depot_save_stack+0x12c/0x490 [ 42.212085] snd_seq_oss_synth_reset+0x398/0x980 [ 42.216808] ? locks_remove_file+0x3fa/0x5a0 [ 42.221179] ? snd_seq_oss_synth_cleanup+0x400/0x400 [ 42.226246] ? __fsnotify_parent+0xb4/0x3a0 [ 42.230532] snd_seq_oss_reset+0x6c/0x260 [ 42.234646] ? free_info_entries+0x36/0x36 [ 42.238842] snd_seq_oss_release+0x71/0x120 [ 42.243125] odev_release+0x52/0x70 [ 42.246715] __fput+0x333/0x7f0 [ 42.249959] ? fput+0x140/0x140 [ 42.253202] ? _raw_spin_unlock_irq+0x27/0x70 [ 42.257660] ____fput+0x15/0x20 [ 42.260902] task_work_run+0x199/0x270 [ 42.264752] ? task_work_cancel+0x210/0x210 [ 42.269038] ? _raw_spin_unlock+0x22/0x30 [ 42.273152] ? switch_task_namespaces+0x87/0xc0 [ 42.277786] do_exit+0xa52/0x1b40 [ 42.281204] ? unwind_dump+0x4c0/0x4c0 [ 42.285056] ? mm_update_next_owner+0x930/0x930 [ 42.289686] ? __kernel_text_address+0xae/0xe0 [ 42.294229] ? unwind_get_return_address+0x61/0xa0 [ 42.299121] ? __save_stack_trace+0x7e/0xd0 [ 42.303407] ? depot_save_stack+0x12c/0x490 [ 42.307697] ? putname+0xee/0x130 [ 42.311113] ? save_stack+0xa3/0xd0 [ 42.314702] ? save_stack_trace+0x16/0x20 [ 42.318813] ? save_stack+0x43/0xd0 [ 42.322400] ? kasan_slab_free+0x71/0xc0 [ 42.326425] ? kmem_cache_free+0x77/0x280 [ 42.330534] ? putname+0xee/0x130 [ 42.333950] ? do_sys_open+0x31b/0x6d0 [ 42.337798] ? SyS_openat+0x30/0x40 [ 42.341388] ? entry_SYSCALL_64_fastpath+0x1f/0xbe [ 42.346279] ? __lock_is_held+0xbc/0x140 [ 42.350307] ? __fd_install+0x2f7/0x6a0 [ 42.354246] ? get_unused_fd_flags+0x190/0x190 [ 42.358795] ? rcu_pm_notify+0xc0/0xc0 [ 42.362646] ? putname+0xee/0x130 [ 42.366061] ? rcu_read_lock_sched_held+0x108/0x120 [ 42.371040] ? kmem_cache_free+0x249/0x280 [ 42.375237] ? putname+0xf3/0x130 [ 42.378652] do_group_exit+0x149/0x400 [ 42.382518] ? filp_open+0x70/0x70 [ 42.386020] ? SyS_exit+0x30/0x30 [ 42.389436] ? trace_hardirqs_on_caller+0x421/0x5c0 [ 42.394417] ? trace_hardirqs_on_thunk+0x1a/0x1c [ 42.399147] SyS_exit_group+0x1d/0x20 [ 42.402911] entry_SYSCALL_64_fastpath+0x1f/0xbe [ 42.407636] RIP: 0033:0x442c58 [ 42.410790] RSP: 002b:00007ffd3c849f48 EFLAGS: 00000246 ORIG_RAX: 00000000000000e7 [ 42.418459] RAX: ffffffffffffffda RBX: 0000000000000000 RCX: 0000000000442c58 [ 42.425692] RDX: 0000000000000000 RSI: 000000000000003c RDI: 0000000000000000 [ 42.432925] RBP: 0000000000000082 R08: 00000000000000e7 R09: ffffffffffffffd0 [ 42.440158] R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000401ca0 [ 42.447391] R13: 0000000000401d30 R14: 0000000000000000 R15: 00000000000000