[ 36.458478] audit: type=1800 audit(1546907792.865:26): pid=7579 uid=0 auid=4294967295 ses=4294967295 subj==unconfined op=collect_data cause=failed(directio) comm="startpar" name="mcstrans" dev="sda1" ino=2457 res=0 [ 36.485435] audit: type=1800 audit(1546907792.865:27): pid=7579 uid=0 auid=4294967295 ses=4294967295 subj==unconfined op=collect_data cause=failed(directio) comm="startpar" name="restorecond" dev="sda1" ino=2436 res=0 [ 36.506432] audit: type=1800 audit(1546907792.865:28): pid=7579 uid=0 auid=4294967295 ses=4294967295 subj==unconfined op=collect_data cause=failed(directio) comm="startpar" name="ssh" dev="sda1" ino=2417 res=0 [....] Starting periodic command scheduler: cron[?25l[?1c7[ ok 8[?25h[?0c. [....] Starting OpenBSD Secure Shell server: sshd[?25l[?1c7[ ok 8[?25h[?0c. [ 37.132241] audit: type=1800 audit(1546907793.555:29): pid=7579 uid=0 auid=4294967295 ses=4294967295 subj==unconfined op=collect_data cause=failed(directio) comm="startpar" name="rc.local" dev="sda1" ino=2432 res=0 Debian GNU/Linux 7 syzkaller ttyS0 syzkaller login: [ 42.536744] sshd (7716) used greatest stack depth: 19848 bytes left Warning: Permanently added '10.128.0.57' (ECDSA) to the list of known hosts. executing program [ 49.092218] [ 49.093877] ====================================================== [ 49.100213] WARNING: possible circular locking dependency detected [ 49.106513] 5.0.0-rc1+ #14 Not tainted [ 49.110376] ------------------------------------------------------ [ 49.116671] syz-executor088/7733 is trying to acquire lock: [ 49.122356] 000000003d578d42 (&pipe->mutex/1){+.+.}, at: fifo_open+0x159/0xb00 [ 49.129705] [ 49.129705] but task is already holding lock: [ 49.135677] 000000005f79aab3 (&sig->cred_guard_mutex){+.+.}, at: __do_execve_file.isra.0+0x45d/0x2700 [ 49.145025] [ 49.145025] which lock already depends on the new lock. [ 49.145025] [ 49.153315] [ 49.153315] the existing dependency chain (in reverse order) is: [ 49.160909] [ 49.160909] -> #1 (&sig->cred_guard_mutex){+.+.}: [ 49.167217] __mutex_lock+0x12f/0x1670 [ 49.171604] mutex_lock_interruptible_nested+0x16/0x20 [ 49.177382] proc_pid_attr_write+0x1fa/0x530 [ 49.182290] __vfs_write+0x116/0xb40 [ 49.186504] __kernel_write+0x110/0x3b0 [ 49.191005] write_pipe_buf+0x180/0x240 [ 49.195483] __splice_from_pipe+0x39a/0x7e0 [ 49.200305] splice_from_pipe+0x1ea/0x310 [ 49.204951] default_file_splice_write+0x3c/0x90 [ 49.210318] do_splice+0x64b/0x1410 [ 49.214443] __x64_sys_splice+0x2c6/0x330 [ 49.219092] do_syscall_64+0x1a3/0x800 [ 49.223497] entry_SYSCALL_64_after_hwframe+0x49/0xbe [ 49.229184] [ 49.229184] -> #0 (&pipe->mutex/1){+.+.}: [ 49.234795] lock_acquire+0x1db/0x570 [ 49.239096] __mutex_lock+0x12f/0x1670 [ 49.243483] mutex_lock_nested+0x16/0x20 [ 49.248048] fifo_open+0x159/0xb00 [ 49.252089] do_dentry_open+0x48a/0x1210 [ 49.256652] vfs_open+0xa0/0xd0 [ 49.260453] path_openat+0x144f/0x5650 [ 49.264842] do_filp_open+0x26f/0x370 [ 49.269141] do_open_execat+0x20e/0x930 [ 49.273612] __do_execve_file.isra.0+0x1966/0x2700 [ 49.279040] __x64_sys_execve+0x8f/0xc0 [ 49.283514] do_syscall_64+0x1a3/0x800 [ 49.287919] entry_SYSCALL_64_after_hwframe+0x49/0xbe [ 49.293606] [ 49.293606] other info that might help us debug this: [ 49.293606] [ 49.301721] Possible unsafe locking scenario: [ 49.301721] [ 49.307752] CPU0 CPU1 [ 49.312415] ---- ---- [ 49.317056] lock(&sig->cred_guard_mutex); [ 49.321357] lock(&pipe->mutex/1); [ 49.327478] lock(&sig->cred_guard_mutex); [ 49.334315] lock(&pipe->mutex/1); [ 49.337919] [ 49.337919] *** DEADLOCK *** [ 49.337919] [ 49.343955] 1 lock held by syz-executor088/7733: [ 49.348688] #0: 000000005f79aab3 (&sig->cred_guard_mutex){+.+.}, at: __do_execve_file.isra.0+0x45d/0x2700 [ 49.358472] [ 49.358472] stack backtrace: [ 49.362951] CPU: 1 PID: 7733 Comm: syz-executor088 Not tainted 5.0.0-rc1+ #14 [ 49.370205] Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 [ 49.379535] Call Trace: [ 49.382102] dump_stack+0x1db/0x2d0 [ 49.385707] ? dump_stack_print_info.cold+0x20/0x20 [ 49.390700] ? print_stack_trace+0x77/0xb0 [ 49.394910] ? vprintk_func+0x86/0x189 [ 49.398777] print_circular_bug.isra.0.cold+0x1cc/0x28f [ 49.404123] __lock_acquire+0x3014/0x4a30 [ 49.408252] ? add_lock_to_list.isra.0+0x450/0x450 [ 49.413162] ? is_bpf_text_address+0xac/0x170 [ 49.417652] ? mark_held_locks+0x100/0x100 [ 49.421867] ? mark_held_locks+0xb1/0x100 [ 49.425997] ? _raw_spin_unlock_irqrestore+0x6b/0xe0 [ 49.431092] ? _raw_spin_unlock_irqrestore+0x6b/0xe0 [ 49.436176] ? lockdep_hardirqs_on+0x415/0x5d0 [ 49.440737] ? trace_hardirqs_off_caller+0x300/0x300 [ 49.445820] ? do_raw_spin_trylock+0x270/0x270 [ 49.450381] ? add_lock_to_list.isra.0+0x450/0x450 [ 49.455290] ? print_usage_bug+0xd0/0xd0 [ 49.459329] ? _raw_spin_unlock_irqrestore+0xa4/0xe0 [ 49.464411] ? __lock_is_held+0xb6/0x140 [ 49.468452] lock_acquire+0x1db/0x570 [ 49.472235] ? fifo_open+0x159/0xb00 [ 49.475931] ? ___might_sleep+0x1e7/0x310 [ 49.480071] ? lock_release+0xc40/0xc40 [ 49.484029] ? fifo_open+0x159/0xb00 [ 49.487723] ? fifo_open+0x159/0xb00 [ 49.491427] __mutex_lock+0x12f/0x1670 [ 49.495294] ? fifo_open+0x159/0xb00 [ 49.498987] ? __sanitizer_cov_trace_const_cmp4+0x16/0x20 [ 49.504504] ? fifo_open+0x159/0xb00 [ 49.508204] ? check_preemption_disabled+0x48/0x290 [ 49.513371] ? lockdep_init_map+0x10c/0x5b0 [ 49.517673] ? mutex_trylock+0x2d0/0x2d0 [ 49.521716] ? add_lock_to_list.isra.0+0x450/0x450 [ 49.526626] ? __mutex_init+0x1f6/0x2a0 [ 49.530578] ? psi_task_change.cold+0x1ec/0x1ec [ 49.535234] ? fifo_open+0x2b5/0xb00 [ 49.538933] ? find_held_lock+0x35/0x120 [ 49.542980] ? fifo_open+0x2b5/0xb00 [ 49.546673] ? lock_acquire+0x1db/0x570 [ 49.550627] ? kasan_check_read+0x11/0x20 [ 49.554754] ? do_raw_spin_unlock+0xa0/0x330 [ 49.559147] ? do_raw_spin_trylock+0x270/0x270 [ 49.563748] mutex_lock_nested+0x16/0x20 [ 49.567800] ? _raw_spin_unlock+0x2d/0x50 [ 49.571925] ? mutex_lock_nested+0x16/0x20 [ 49.576140] fifo_open+0x159/0xb00 [ 49.579664] do_dentry_open+0x48a/0x1210 [ 49.583706] ? pipe_release+0x280/0x280 [ 49.587672] ? chown_common+0x740/0x740 [ 49.591636] ? security_inode_permission+0xd5/0x110 [ 49.596630] ? inode_permission+0xb4/0x570 [ 49.600842] vfs_open+0xa0/0xd0 [ 49.604346] path_openat+0x144f/0x5650 [ 49.608215] ? is_bpf_text_address+0xd3/0x170 [ 49.612692] ? path_lookupat.isra.0+0xba0/0xba0 [ 49.617343] ? __lock_acquire+0x572/0x4a30 [ 49.621555] ? kmem_cache_alloc+0x12d/0x710 [ 49.625856] ? __do_execve_file.isra.0+0x47a/0x2700 [ 49.630850] ? __x64_sys_execve+0x8f/0xc0 [ 49.634983] ? do_syscall_64+0x1a3/0x800 [ 49.639079] ? entry_SYSCALL_64_after_hwframe+0x49/0xbe [ 49.644426] ? add_lock_to_list.isra.0+0x450/0x450 [ 49.649337] do_filp_open+0x26f/0x370 [ 49.653117] ? may_open_dev+0x100/0x100 [ 49.657071] ? refcount_add_not_zero_checked+0x330/0x330 [ 49.662505] ? prepare_creds+0xa4/0x4e0 [ 49.666458] ? add_lock_to_list.isra.0+0x450/0x450 [ 49.671367] ? add_lock_to_list.isra.0+0x450/0x450 [ 49.676280] ? __do_execve_file.isra.0+0x901/0x2700 [ 49.681277] do_open_execat+0x20e/0x930 [ 49.685233] ? unregister_binfmt+0x2b0/0x2b0 [ 49.689622] ? kasan_check_read+0x11/0x20 [ 49.693750] ? do_raw_spin_trylock+0x270/0x270 [ 49.698314] ? __phys_addr_symbol+0x30/0x70 [ 49.702614] __do_execve_file.isra.0+0x1966/0x2700 [ 49.707532] ? copy_strings_kernel+0x110/0x110 [ 49.712098] ? __sanitizer_cov_trace_const_cmp8+0x18/0x20 [ 49.717613] ? strncpy_from_user+0x3aa/0x4e0 [ 49.722016] ? digsig_verify.cold+0x32/0x32 [ 49.726321] ? kmem_cache_alloc+0x341/0x710 [ 49.730622] ? do_syscall_64+0x8c/0x800 [ 49.734577] ? lockdep_hardirqs_on+0x415/0x5d0 [ 49.739139] ? __sanitizer_cov_trace_const_cmp4+0x16/0x20 [ 49.744656] ? getname_flags+0x277/0x5b0 [ 49.748697] ? trace_hardirqs_off_caller+0x300/0x300 [ 49.753780] __x64_sys_execve+0x8f/0xc0 [ 49.757736] do_syscall_64+0x1a3/0x800 [ 49.761604] ? syscall_return_slowpath+0x5f0/0x5f0 [ 49.766514] ? prepare_exit_to_usermode+0x3b0/0x3b0 [ 49.771512] ? __switch_to_asm+0x34/0x70 [ 49.775566] ? trace_hardirqs_off_thunk+0x1a/0x1c [ 49.780396] entry_SYSCALL_64_after_hwframe+0x49/0xbe [ 49.785571] RIP: 0033:0x445709 [ 49.788747] Code: e8 ec b8 02 00 48 83 c4 18 c3 0f 1f 80 00 00 00 00 48 89 f8 48 89 f7 48 89 d6 48 89 ca 4d 89 c2 4d 89 c8 4c 8b 4c 24 08 0f 05 <48> 3d 01 f0 ff ff 0f 83 8b 12 fc ff c3 66 2e 0f 1f 84 00 00 00 00 [ 49.807638] RSP: 002b:00007f816e2d6d18 EFLAGS: 00000246 ORIG_RAX: 000000000000003b [ 49.815328] RAX: ffffffffffffffda RBX: 00000000006dac58 RCX: 0000000000445709 [ 49.822591] RDX: 0000000000000000 RSI: 0000000000000000 RDI: 0000000020000380 [ 49.829842] RBP: 00000000006dac50 R08: 68742f636f72702f R09: 68742f636f72702f [ 49.837092] R10: 0000000000000000 R11: 0000000000000246 R12: 00000000006dac5c [ 49.844339]