[....] Starting OpenBSD Secure Shell server: sshd[?25l[?1c7[ ok 8[?25h[?0c.
[....] Starting file context maintaining daemon: restorecond[?25l[?1c7[1[   33.552463] kauditd_printk_skb: 9 callbacks suppressed
G[ ok [39;[   33.552476] audit: type=1800 audit(1542444419.450:33): pid=5985 uid=0 auid=4294967295 ses=4294967295 subj=system_u:system_r:kernel_t:s0 op=collect_data cause=failed(directio) comm="startpar" name="rc.local" dev="sda1" ino=2432 res=0
49m8[?25h[?0c[   33.581675] audit: type=1800 audit(1542444419.460:34): pid=5985 uid=0 auid=4294967295 ses=4294967295 subj=system_u:system_r:kernel_t:s0 op=collect_data cause=failed(directio) comm="startpar" name="rmnologin" dev="sda1" ino=2423 res=0
.

Debian GNU/Linux 7 syzkaller ttyS0

syzkaller login: [   38.930277] audit: type=1400 audit(1542444424.830:35): avc:  denied  { map } for  pid=6164 comm="bash" path="/bin/bash" dev="sda1" ino=1457 scontext=unconfined_u:system_r:insmod_t:s0-s0:c0.c1023 tcontext=system_u:object_r:file_t:s0 tclass=file permissive=1
[   38.966682] sshd (6162) used greatest stack depth: 15744 bytes left
Warning: Permanently added '10.128.10.30' (ECDSA) to the list of known hosts.
executing program
[   45.642822] audit: type=1400 audit(1542444431.540:36): avc:  denied  { map } for  pid=6177 comm="syz-executor105" path="/root/syz-executor105348405" dev="sda1" ino=16484 scontext=unconfined_u:system_r:insmod_t:s0-s0:c0.c1023 tcontext=unconfined_u:object_r:user_home_t:s0 tclass=file permissive=1
[   45.695679] 
[   45.697344] ======================================================
[   45.703652] WARNING: possible circular locking dependency detected
[   45.710076] 4.20.0-rc2+ #117 Not tainted
[   45.714117] ------------------------------------------------------
[   45.720416] kworker/1:1/22 is trying to acquire lock:
[   45.725588] 00000000abeb5a68 (&mdev->req_queue_mutex){+.+.}, at: v4l2_release+0x1d7/0x3a0
[   45.733914] 
[   45.733914] but task is already holding lock:
[   45.739867] 000000008c71eda2 ((delayed_fput_work).work){+.+.}, at: process_one_work+0xb9a/0x1c40
[   45.748784] 
[   45.748784] which lock already depends on the new lock.
[   45.748784] 
[   45.757082] 
[   45.757082] the existing dependency chain (in reverse order) is:
[   45.764687] 
[   45.764687] -> #3 ((delayed_fput_work).work){+.+.}:
[   45.771176]        process_one_work+0xc0a/0x1c40
[   45.775936]        worker_thread+0x17f/0x1390
[   45.780419]        kthread+0x35a/0x440
[   45.784288]        ret_from_fork+0x3a/0x50
[   45.788500] 
[   45.788500] -> #2 ((wq_completion)"events"){+.+.}:
[   45.794895]        flush_workqueue+0x30a/0x1e10
[   45.799551]        vim2m_stop_streaming+0x7c/0x2c0
[   45.804468]        __vb2_queue_cancel+0x171/0xd20
[   45.809297]        vb2_core_queue_release+0x26/0x80
[   45.814301]        vb2_queue_release+0x15/0x20
[   45.818877]        v4l2_m2m_ctx_release+0x1e/0x35
[   45.823709]        vim2m_release+0xe6/0x150
[   45.828014]        v4l2_release+0x224/0x3a0
[   45.832321]        __fput+0x385/0xa30
[   45.836114]        ____fput+0x15/0x20
[   45.839898]        task_work_run+0x1e8/0x2a0
[   45.844293]        exit_to_usermode_loop+0x318/0x380
[   45.849380]        do_syscall_64+0x6be/0x820
[   45.853774]        entry_SYSCALL_64_after_hwframe+0x49/0xbe
[   45.859459] 
[   45.859459] -> #1 (&dev->dev_mutex){+.+.}:
[   45.865164]        __mutex_lock+0x166/0x16f0
[   45.869554]        mutex_lock_nested+0x16/0x20
[   45.874119]        vim2m_release+0xbc/0x150
[   45.878548]        v4l2_release+0x224/0x3a0
[   45.882852]        __fput+0x385/0xa30
[   45.886636]        ____fput+0x15/0x20
[   45.890420]        task_work_run+0x1e8/0x2a0
[   45.894810]        exit_to_usermode_loop+0x318/0x380
[   45.899893]        do_syscall_64+0x6be/0x820
[   45.904286]        entry_SYSCALL_64_after_hwframe+0x49/0xbe
[   45.909973] 
[   45.909973] -> #0 (&mdev->req_queue_mutex){+.+.}:
[   45.916281]        lock_acquire+0x1ed/0x520
[   45.920585]        __mutex_lock+0x166/0x16f0
[   45.924974]        mutex_lock_nested+0x16/0x20
[   45.929538]        v4l2_release+0x1d7/0x3a0
[   45.933842]        __fput+0x385/0xa30
[   45.937633]        delayed_fput+0x55/0x80
[   45.941765]        process_one_work+0xc90/0x1c40
[   45.946501]        worker_thread+0x17f/0x1390
[   45.950980]        kthread+0x35a/0x440
[   45.954854]        ret_from_fork+0x3a/0x50
[   45.959063] 
[   45.959063] other info that might help us debug this:
[   45.959063] 
[   45.967183] Chain exists of:
[   45.967183]   &mdev->req_queue_mutex --> (wq_completion)"events" --> (delayed_fput_work).work
[   45.967183] 
[   45.980178]  Possible unsafe locking scenario:
[   45.980178] 
[   45.986223]        CPU0                    CPU1
[   45.990868]        ----                    ----
[   45.995513]   lock((delayed_fput_work).work);
[   45.999987]                                lock((wq_completion)"events");
[   46.006891]                                lock((delayed_fput_work).work);
[   46.013884]   lock(&mdev->req_queue_mutex);
[   46.018296] 
[   46.018296]  *** DEADLOCK ***
[   46.018296] 
[   46.024344] 2 locks held by kworker/1:1/22:
[   46.028719]  #0: 000000000996fc86 ((wq_completion)"events"){+.+.}, at: process_one_work+0xb43/0x1c40
[   46.037985]  #1: 000000008c71eda2 ((delayed_fput_work).work){+.+.}, at: process_one_work+0xb9a/0x1c40
[   46.047326] 
[   46.047326] stack backtrace:
[   46.051807] CPU: 1 PID: 22 Comm: kworker/1:1 Not tainted 4.20.0-rc2+ #117
[   46.058716] Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
[   46.068061] Workqueue: events delayed_fput
[   46.072273] Call Trace:
[   46.074847]  dump_stack+0x244/0x39d
[   46.078472]  ? dump_stack_print_info.cold.1+0x20/0x20
[   46.083648]  ? vprintk_func+0x85/0x181
[   46.087520]  print_circular_bug.isra.35.cold.54+0x1bd/0x27d
[   46.093212]  ? save_trace+0xe0/0x290
[   46.096922]  __lock_acquire+0x3399/0x4c20
[   46.101079]  ? mark_held_locks+0x130/0x130
[   46.105316]  ? print_usage_bug+0xc0/0xc0
[   46.109366]  ? lock_unpin_lock+0x4a0/0x4a0
[   46.113589]  ? __lock_acquire+0x62f/0x4c20
[   46.117818]  ? trace_hardirqs_on+0x310/0x310
[   46.122215]  ? lock_pin_lock+0x350/0x350
[   46.126258]  ? zap_class+0x640/0x640
[   46.129959]  ? mark_held_locks+0x130/0x130
[   46.134176]  ? load_balance+0x687/0x39a0
[   46.138236]  lock_acquire+0x1ed/0x520
[   46.142021]  ? v4l2_release+0x1d7/0x3a0
[   46.145982]  ? lock_release+0xa00/0xa00
[   46.149941]  ? perf_trace_sched_process_exec+0x860/0x860
[   46.155372]  ? find_busiest_group+0x2060/0x2060
[   46.160034]  ? print_usage_bug+0xc0/0xc0
[   46.164088]  ? v4l2_release+0x1d7/0x3a0
[   46.168055]  __mutex_lock+0x166/0x16f0
[   46.171926]  ? v4l2_release+0x1d7/0x3a0
[   46.175883]  ? v4l2_release+0x1d7/0x3a0
[   46.179848]  ? mutex_trylock+0x2b0/0x2b0
[   46.183903]  ? __lock_acquire+0x62f/0x4c20
[   46.188146]  ? mark_held_locks+0x130/0x130
[   46.192381]  ? mark_held_locks+0x130/0x130
[   46.196600]  ? mark_held_locks+0x130/0x130
[   46.200827]  ? lock_downgrade+0x900/0x900
[   46.204960]  ? zap_class+0x640/0x640
[   46.208656]  ? trace_event_raw_event_lock+0x340/0x340
[   46.213835]  ? kvm_sched_clock_read+0x9/0x20
[   46.218236]  ? zap_class+0x640/0x640
[   46.221935]  ? zap_class+0x640/0x640
[   46.225645]  ? __sanitizer_cov_trace_const_cmp4+0x16/0x20
[   46.231165]  ? fsnotify+0x4e5/0xf20
[   46.234784]  ? __lock_is_held+0xb5/0x140
[   46.238832]  ? __sanitizer_cov_trace_const_cmp8+0x18/0x20
[   46.244379]  ? locks_remove_file+0x3c6/0x5c0
[   46.248790]  ? __sanitizer_cov_trace_const_cmp2+0x18/0x20
[   46.254308]  ? ima_file_free+0x132/0x650
[   46.258353]  ? fsnotify_first_mark+0x350/0x350
[   46.262921]  ? ima_file_check+0x130/0x130
[   46.267056]  ? vivid_remove+0x460/0x460
[   46.271029]  mutex_lock_nested+0x16/0x20
[   46.275089]  ? mutex_lock_nested+0x16/0x20
[   46.279440]  v4l2_release+0x1d7/0x3a0
[   46.283230]  ? dev_debug_store+0x140/0x140
[   46.287452]  __fput+0x385/0xa30
[   46.290721]  ? get_max_files+0x20/0x20
[   46.294598]  delayed_fput+0x55/0x80
[   46.298369]  process_one_work+0xc90/0x1c40
[   46.302705]  ? mark_held_locks+0x130/0x130
[   46.307049]  ? pwq_dec_nr_in_flight+0x4a0/0x4a0
[   46.311716]  ? __switch_to_asm+0x40/0x70
[   46.315803]  ? __switch_to_asm+0x34/0x70
[   46.319853]  ? __switch_to_asm+0x34/0x70
[   46.323895]  ? __switch_to_asm+0x40/0x70
[   46.327939]  ? __switch_to_asm+0x34/0x70
[   46.331987]  ? __switch_to_asm+0x40/0x70
[   46.336029]  ? __switch_to_asm+0x34/0x70
[   46.340196]  ? __switch_to_asm+0x40/0x70
[   46.344276]  ? __schedule+0x8d7/0x21d0
[   46.348177]  ? lock_downgrade+0x900/0x900
[   46.352303]  ? zap_class+0x640/0x640
[   46.356011]  ? find_held_lock+0x36/0x1c0
[   46.360057]  ? lock_acquire+0x1ed/0x520
[   46.364021]  ? worker_thread+0x3e0/0x1390
[   46.368147]  ? kasan_check_read+0x11/0x20
[   46.372277]  ? do_raw_spin_lock+0x14f/0x350
[   46.376727]  ? kasan_check_read+0x11/0x20
[   46.380883]  ? rwlock_bug.part.2+0x90/0x90
[   46.385116]  ? trace_hardirqs_on+0x310/0x310
[   46.389524]  worker_thread+0x17f/0x1390
[   46.393582]  ? __switch_to_asm+0x34/0x70
[   46.397824]  ? process_one_work+0x1c40/0x1c40
[   46.402308]  ? zap_class+0x640/0x640
[   46.406115]  ? find_held_lock+0x36/0x1c0
[   46.410170]  ? __kthread_parkme+0xce/0x1a0
[   46.414387]  ? _raw_spin_unlock_irqrestore+0x82/0xd0
[   46.419488]  ? _raw_spin_unlock_irqrestore+0x82/0xd0
[   46.424579]  ? lockdep_hardirqs_on+0x3bb/0x5b0
[   46.429145]  ? trace_hardirqs_on+0xbd/0x310
[   46.433462]  ? kasan_check_read+0x11/0x20
[   46.437594]  ? __kthread_parkme+0xce/0x1a0
[   46.441844]  ? trace_hardirqs_off_caller+0x310/0x310
executing program
[   46.446948]  ? trace_hardirqs_off_caller+0x310/0x310
[   46.452038]  ? _raw_spin_unlock_irqrestore+0x6d/0xd0
[   46.457153]  ? __sanitizer_cov_trace_const_cmp8+0x18/0x20
[   46.462696]  ? __kthread_parkme+0xfb/0x1a0
[   46.466925]  ? process_one_work+0x1c40/0x1c40
[   46.471412]  kthread+0x35a/0x440
[   46.474781]  ? kthread_stop+0x900/0x900
[   46.478798]  ret_from_fork+0x3a/0x50
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