[ 35.269999][ T26] audit: type=1800 audit(1553304728.738:27): pid=7415 uid=0 auid=4294967295 ses=4294967295 subj==unconfined op=collect_data cause=failed(directio) comm="startpar" name="restorecond" dev="sda1" ino=2436 res=0 [ 35.270021][ T26] audit: type=1800 audit(1553304728.738:28): pid=7415 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. [ 36.119679][ T26] audit: type=1800 audit(1553304729.628:29): pid=7415 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 [ 36.140222][ T26] audit: type=1800 audit(1553304729.628:30): pid=7415 uid=0 auid=4294967295 ses=4294967295 subj==unconfined op=collect_data cause=failed(directio) comm="startpar" name="rmnologin" dev="sda1" ino=2423 res=0 Debian GNU/Linux 7 syzkaller ttyS0 Warning: Permanently added '10.128.0.189' (ECDSA) to the list of known hosts. executing program syzkaller login: [ 45.905464][ T7567] [ 45.910082][ T7567] ====================================================== [ 45.920139][ T7567] WARNING: possible circular locking dependency detected [ 45.933939][ T7567] 5.1.0-rc1-next-20190322 #9 Not tainted [ 45.942546][ T7567] ------------------------------------------------------ [ 45.952295][ T7567] syz-executor899/7567 is trying to acquire lock: [ 45.961248][ T7567] 0000000064d66754 (&pipe->mutex/1){+.+.}, at: fifo_open+0x159/0xb00 [ 45.971681][ T7567] [ 45.971681][ T7567] but task is already holding lock: [ 45.982151][ T7567] 000000009806e6b2 (&sig->cred_guard_mutex){+.+.}, at: __do_execve_file.isra.0+0x376/0x23f0 [ 46.001244][ T7567] [ 46.001244][ T7567] which lock already depends on the new lock. [ 46.001244][ T7567] [ 46.022231][ T7567] [ 46.022231][ T7567] the existing dependency chain (in reverse order) is: [ 46.042293][ T7567] [ 46.042293][ T7567] -> #1 (&sig->cred_guard_mutex){+.+.}: [ 46.052990][ T7567] lock_acquire+0x16f/0x3f0 [ 46.059487][ T7567] __mutex_lock+0xf7/0x1310 [ 46.065729][ T7567] mutex_lock_interruptible_nested+0x16/0x20 [ 46.076628][ T7567] proc_pid_attr_write+0x200/0x580 [ 46.092080][ T7567] __vfs_write+0x8d/0x110 [ 46.114194][ T7567] __kernel_write+0x110/0x3b0 [ 46.126803][ T7567] write_pipe_buf+0x15d/0x1f0 [ 46.143730][ T7567] __splice_from_pipe+0x395/0x7d0 [ 46.155921][ T7567] splice_from_pipe+0x108/0x170 [ 46.165157][ T7567] default_file_splice_write+0x3c/0x90 [ 46.174812][ T7567] do_splice+0x70a/0x13c0 [ 46.183952][ T7567] __x64_sys_splice+0x2c6/0x330 [ 46.194651][ T7567] do_syscall_64+0x103/0x610 [ 46.203360][ T7567] entry_SYSCALL_64_after_hwframe+0x49/0xbe [ 46.215281][ T7567] [ 46.215281][ T7567] -> #0 (&pipe->mutex/1){+.+.}: [ 46.227739][ T7567] __lock_acquire+0x239c/0x3fb0 [ 46.236543][ T7567] lock_acquire+0x16f/0x3f0 [ 46.245222][ T7567] __mutex_lock+0xf7/0x1310 [ 46.251456][ T7567] mutex_lock_nested+0x16/0x20 [ 46.258687][ T7567] fifo_open+0x159/0xb00 [ 46.267302][ T7567] do_dentry_open+0x488/0x1160 [ 46.277742][ T7567] vfs_open+0xa0/0xd0 [ 46.284747][ T7567] path_openat+0x10e9/0x46e0 [ 46.293266][ T7567] do_filp_open+0x1a1/0x280 [ 46.299645][ T7567] do_open_execat+0x137/0x690 [ 46.306944][ T7567] __do_execve_file.isra.0+0x178d/0x23f0 [ 46.315941][ T7567] __x64_sys_execve+0x8f/0xc0 [ 46.322398][ T7567] do_syscall_64+0x103/0x610 [ 46.329590][ T7567] entry_SYSCALL_64_after_hwframe+0x49/0xbe [ 46.338937][ T7567] [ 46.338937][ T7567] other info that might help us debug this: [ 46.338937][ T7567] [ 46.353549][ T7567] Possible unsafe locking scenario: [ 46.353549][ T7567] [ 46.363356][ T7567] CPU0 CPU1 [ 46.371543][ T7567] ---- ---- [ 46.378154][ T7567] lock(&sig->cred_guard_mutex); [ 46.385088][ T7567] lock(&pipe->mutex/1); [ 46.394204][ T7567] lock(&sig->cred_guard_mutex); [ 46.403595][ T7567] lock(&pipe->mutex/1); [ 46.409352][ T7567] [ 46.409352][ T7567] *** DEADLOCK *** [ 46.409352][ T7567] [ 46.426006][ T7567] 1 lock held by syz-executor899/7567: [ 46.434282][ T7567] #0: 000000009806e6b2 (&sig->cred_guard_mutex){+.+.}, at: __do_execve_file.isra.0+0x376/0x23f0 [ 46.450146][ T7567] [ 46.450146][ T7567] stack backtrace: [ 46.460411][ T7567] CPU: 1 PID: 7567 Comm: syz-executor899 Not tainted 5.1.0-rc1-next-20190322 #9 [ 46.474994][ T7567] Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 [ 46.490559][ T7567] Call Trace: [ 46.494689][ T7567] dump_stack+0x172/0x1f0 [ 46.500625][ T7567] print_circular_bug.isra.0.cold+0x1cc/0x28f [ 46.509930][ T7567] check_prev_add.constprop.0+0xf11/0x23c0 [ 46.517713][ T7567] ? depot_save_stack+0x1de/0x460 [ 46.525128][ T7567] ? check_usage+0x570/0x570 [ 46.531753][ T7567] ? mark_held_locks+0xa4/0xf0 [ 46.537948][ T7567] ? _raw_spin_unlock_irqrestore+0x6b/0xe0 [ 46.546889][ T7567] ? graph_lock+0x7b/0x200 [ 46.552426][ T7567] ? __lockdep_reset_lock+0x450/0x450 [ 46.559542][ T7567] ? __sanitizer_cov_trace_const_cmp8+0x18/0x20 [ 46.567785][ T7567] __lock_acquire+0x239c/0x3fb0 [ 46.574013][ T7567] ? save_stack+0xa9/0xd0 [ 46.579728][ T7567] ? mark_held_locks+0xf0/0xf0 [ 46.587579][ T7567] lock_acquire+0x16f/0x3f0 [ 46.594607][ T7567] ? fifo_open+0x159/0xb00 [ 46.600391][ T7567] ? fifo_open+0x159/0xb00 [ 46.606646][ T7567] __mutex_lock+0xf7/0x1310 [ 46.611973][ T7567] ? fifo_open+0x159/0xb00 [ 46.620550][ T7567] ? fifo_open+0x159/0xb00 [ 46.628196][ T7567] ? fifo_open+0x2b5/0xb00 [ 46.633148][ T7567] ? mutex_trylock+0x1e0/0x1e0 [ 46.641114][ T7567] ? fifo_open+0x2b5/0xb00 [ 46.648007][ T7567] ? kasan_check_write+0x14/0x20 [ 46.655107][ T7567] ? lock_downgrade+0x880/0x880 [ 46.663058][ T7567] mutex_lock_nested+0x16/0x20 [ 46.668820][ T7567] ? mutex_lock_nested+0x16/0x20 [ 46.674900][ T7567] fifo_open+0x159/0xb00 [ 46.681942][ T7567] do_dentry_open+0x488/0x1160 [ 46.689956][ T7567] ? pipe_release+0x280/0x280 [ 46.696077][ T7567] ? chown_common+0x5c0/0x5c0 [ 46.703042][ T7567] ? inode_permission+0xb4/0x570 [ 46.709512][ T7567] vfs_open+0xa0/0xd0 [ 46.714445][ T7567] path_openat+0x10e9/0x46e0 [ 46.720360][ T7567] ? path_lookupat.isra.0+0x8d0/0x8d0 [ 46.727577][ T7567] ? __kmalloc+0x15c/0x740 [ 46.733123][ T7567] ? prepare_creds+0x2f5/0x3f0 [ 46.739473][ T7567] ? prepare_exec_creds+0x12/0xf0 [ 46.745221][ T7567] ? __do_execve_file.isra.0+0x393/0x23f0 [ 46.752320][ T7567] ? do_syscall_64+0x103/0x610 [ 46.758764][ T7567] ? entry_SYSCALL_64_after_hwframe+0x49/0xbe [ 46.767654][ T7567] ? __lock_acquire+0x548/0x3fb0 [ 46.774001][ T7567] ? prepare_exec_creds+0x12/0xf0 [ 46.781596][ T7567] ? __do_execve_file.isra.0+0x393/0x23f0 [ 46.790025][ T7567] ? __x64_sys_execve+0x8f/0xc0 [ 46.795437][ T7567] do_filp_open+0x1a1/0x280 [ 46.800862][ T7567] ? may_open_dev+0x100/0x100 [ 46.807380][ T7567] ? __lock_acquire+0x548/0x3fb0 [ 46.813503][ T7567] do_open_execat+0x137/0x690 [ 46.819544][ T7567] ? unregister_binfmt+0x170/0x170 [ 46.825769][ T7567] ? lock_downgrade+0x880/0x880 [ 46.832221][ T7567] ? __sanitizer_cov_trace_const_cmp4+0x16/0x20 [ 46.839404][ T7567] ? kasan_check_read+0x11/0x20 [ 46.846753][ T7567] ? do_raw_spin_unlock+0x57/0x270 [ 46.853518][ T7567] __do_execve_file.isra.0+0x178d/0x23f0 [ 46.861502][ T7567] ? __sanitizer_cov_trace_cmp8+0x18/0x20 [ 46.869852][ T7567] ? __check_object_size+0x3d/0x42f [ 46.875924][ T7567] ? copy_strings_kernel+0x110/0x110 [ 46.882684][ T7567] ? __sanitizer_cov_trace_const_cmp4+0x16/0x20 [ 46.890862][ T7567] ? getname_flags+0x277/0x5b0 [ 46.896966][ T7567] ? entry_SYSCALL_64_after_hwframe+0x49/0xbe [ 46.904024][ T7567] __x64_sys_execve+0x8f/0xc0 [ 46.909506][ T7567] do_syscall_64+0x103/0x610 [ 46.914823][ T7567] entry_SYSCALL_64_after_hwframe+0x49/0xbe [ 46.922527][ T7567] RIP: 0033:0x4402a9 [ 46.928675][ T7567] Code: 18 89 d0 c3 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 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 fb 13 fc ff c3 66 2e 0f 1f 84 00 00 00 00 [ 46.954338][ T7567] RSP: 002b:00007ffd802425c8 EFLAGS: 00000246 ORIG_RAX: 000000000000003b [ 46.963756][ T7567] RAX: ffffffffffffffda RBX: 00000000004002c8 RCX: 00000000004402a9 [ 46.977994][ T7567] RDX: 0000000000000000 RSI: 0000000000000000 RDI: 0000000020000480 [ 46.997639][ T7567] RBP: 00000000006ca018 R08: 0000000000000000 R09: 0000000000000000 [ 47.018253][ T7567] R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000401b30 [ 47.030582][ T7567] R13: 0000000000401bc0 R14: 0000000000000000 R15: 0000000000000000