[ 37.999676][ T26] audit: type=1800 audit(1553304710.541:27): pid=7593 uid=0 auid=4294967295 ses=4294967295 subj==unconfined op=collect_data cause=failed(directio) comm="startpar" name="restorecond" dev="sda1" ino=2436 res=0 [ 38.027868][ T26] audit: type=1800 audit(1553304710.541:28): pid=7593 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. [ 38.734423][ T26] audit: type=1800 audit(1553304711.341:29): pid=7593 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 [ 38.755367][ T26] audit: type=1800 audit(1553304711.361:30): pid=7593 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 '10.128.0.107' (ECDSA) to the list of known hosts. executing program syzkaller login: [ 45.543213][ T7744] [ 45.545563][ T7744] ====================================================== [ 45.552554][ T7744] WARNING: possible circular locking dependency detected [ 45.559571][ T7744] 5.1.0-rc1+ #33 Not tainted [ 45.564143][ T7744] ------------------------------------------------------ [ 45.571132][ T7744] syz-executor094/7744 is trying to acquire lock: [ 45.577512][ T7744] 000000005a9b1c56 (&pipe->mutex/1){+.+.}, at: fifo_open+0x159/0xb00 [ 45.585633][ T7744] [ 45.585633][ T7744] but task is already holding lock: [ 45.592971][ T7744] 000000004719af08 (&sig->cred_guard_mutex){+.+.}, at: __do_execve_file.isra.0+0x376/0x23f0 [ 45.603109][ T7744] [ 45.603109][ T7744] which lock already depends on the new lock. [ 45.603109][ T7744] [ 45.613483][ T7744] [ 45.613483][ T7744] the existing dependency chain (in reverse order) is: [ 45.622467][ T7744] [ 45.622467][ T7744] -> #1 (&sig->cred_guard_mutex){+.+.}: [ 45.630280][ T7744] lock_acquire+0x16f/0x3f0 [ 45.635287][ T7744] __mutex_lock+0xf7/0x1310 [ 45.640287][ T7744] mutex_lock_interruptible_nested+0x16/0x20 [ 45.646760][ T7744] proc_pid_attr_write+0x200/0x580 [ 45.652364][ T7744] __vfs_write+0x8d/0x110 [ 45.657186][ T7744] __kernel_write+0x110/0x3b0 [ 45.662355][ T7744] write_pipe_buf+0x15d/0x1f0 [ 45.667530][ T7744] __splice_from_pipe+0x395/0x7d0 [ 45.673046][ T7744] splice_from_pipe+0x108/0x170 [ 45.678389][ T7744] default_file_splice_write+0x3c/0x90 [ 45.684338][ T7744] do_splice+0x70a/0x13c0 [ 45.689160][ T7744] __x64_sys_splice+0x2c6/0x330 [ 45.694502][ T7744] do_syscall_64+0x103/0x610 [ 45.699584][ T7744] entry_SYSCALL_64_after_hwframe+0x49/0xbe [ 45.705962][ T7744] [ 45.705962][ T7744] -> #0 (&pipe->mutex/1){+.+.}: [ 45.712965][ T7744] __lock_acquire+0x239c/0x3fb0 [ 45.718304][ T7744] lock_acquire+0x16f/0x3f0 [ 45.723299][ T7744] __mutex_lock+0xf7/0x1310 [ 45.728292][ T7744] mutex_lock_nested+0x16/0x20 [ 45.733550][ T7744] fifo_open+0x159/0xb00 [ 45.738288][ T7744] do_dentry_open+0x488/0x1160 [ 45.743543][ T7744] vfs_open+0xa0/0xd0 [ 45.748016][ T7744] path_openat+0x10e9/0x46e0 [ 45.753118][ T7744] do_filp_open+0x1a1/0x280 [ 45.758115][ T7744] do_open_execat+0x137/0x690 [ 45.763301][ T7744] __do_execve_file.isra.0+0x178d/0x23f0 [ 45.769426][ T7744] __x64_sys_execve+0x8f/0xc0 [ 45.774610][ T7744] do_syscall_64+0x103/0x610 [ 45.779691][ T7744] entry_SYSCALL_64_after_hwframe+0x49/0xbe [ 45.786071][ T7744] [ 45.786071][ T7744] other info that might help us debug this: [ 45.786071][ T7744] [ 45.796274][ T7744] Possible unsafe locking scenario: [ 45.796274][ T7744] [ 45.803698][ T7744] CPU0 CPU1 [ 45.809036][ T7744] ---- ---- [ 45.814371][ T7744] lock(&sig->cred_guard_mutex); [ 45.819380][ T7744] lock(&pipe->mutex/1); [ 45.826198][ T7744] lock(&sig->cred_guard_mutex); [ 45.833705][ T7744] lock(&pipe->mutex/1); [ 45.838002][ T7744] [ 45.838002][ T7744] *** DEADLOCK *** [ 45.838002][ T7744] [ 45.846119][ T7744] 1 lock held by syz-executor094/7744: [ 45.851544][ T7744] #0: 000000004719af08 (&sig->cred_guard_mutex){+.+.}, at: __do_execve_file.isra.0+0x376/0x23f0 [ 45.862021][ T7744] [ 45.862021][ T7744] stack backtrace: [ 45.867891][ T7744] CPU: 1 PID: 7744 Comm: syz-executor094 Not tainted 5.1.0-rc1+ #33 [ 45.875849][ T7744] Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 [ 45.885882][ T7744] Call Trace: [ 45.889151][ T7744] dump_stack+0x172/0x1f0 [ 45.893461][ T7744] print_circular_bug.isra.0.cold+0x1cc/0x28f [ 45.899511][ T7744] check_prev_add.constprop.0+0xf11/0x23c0 [ 45.905305][ T7744] ? depot_save_stack+0x1de/0x460 [ 45.910304][ T7744] ? check_usage+0x570/0x570 [ 45.914866][ T7744] ? mark_held_locks+0xa4/0xf0 [ 45.919618][ T7744] ? _raw_spin_unlock_irqrestore+0x6b/0xe0 [ 45.925398][ T7744] ? graph_lock+0x7b/0x200 [ 45.929788][ T7744] ? __lockdep_reset_lock+0x450/0x450 [ 45.935146][ T7744] ? __sanitizer_cov_trace_const_cmp8+0x18/0x20 [ 45.941359][ T7744] __lock_acquire+0x239c/0x3fb0 [ 45.946189][ T7744] ? save_stack+0xa9/0xd0 [ 45.950491][ T7744] ? mark_held_locks+0xf0/0xf0 [ 45.955230][ T7744] lock_acquire+0x16f/0x3f0 [ 45.959985][ T7744] ? fifo_open+0x159/0xb00 [ 45.964380][ T7744] ? fifo_open+0x159/0xb00 [ 45.968766][ T7744] __mutex_lock+0xf7/0x1310 [ 45.973244][ T7744] ? fifo_open+0x159/0xb00 [ 45.977631][ T7744] ? fifo_open+0x159/0xb00 [ 45.982019][ T7744] ? fifo_open+0x2b5/0xb00 [ 45.986410][ T7744] ? mutex_trylock+0x1e0/0x1e0 [ 45.991146][ T7744] ? fifo_open+0x2b5/0xb00 [ 45.995536][ T7744] ? kasan_check_write+0x14/0x20 [ 46.000447][ T7744] ? lock_downgrade+0x880/0x880 [ 46.005282][ T7744] mutex_lock_nested+0x16/0x20 [ 46.010019][ T7744] ? mutex_lock_nested+0x16/0x20 [ 46.014926][ T7744] fifo_open+0x159/0xb00 [ 46.019160][ T7744] do_dentry_open+0x488/0x1160 [ 46.023899][ T7744] ? pipe_release+0x280/0x280 [ 46.028555][ T7744] ? chown_common+0x5c0/0x5c0 [ 46.033205][ T7744] ? inode_permission+0xb4/0x570 [ 46.038114][ T7744] vfs_open+0xa0/0xd0 [ 46.042069][ T7744] path_openat+0x10e9/0x46e0 [ 46.046650][ T7744] ? path_lookupat.isra.0+0x8d0/0x8d0 [ 46.052081][ T7744] ? __kmalloc+0x15c/0x740 [ 46.056478][ T7744] ? prepare_creds+0x2f5/0x3f0 [ 46.061231][ T7744] ? prepare_exec_creds+0x12/0xf0 [ 46.066239][ T7744] ? __do_execve_file.isra.0+0x393/0x23f0 [ 46.071930][ T7744] ? do_syscall_64+0x103/0x610 [ 46.076666][ T7744] ? entry_SYSCALL_64_after_hwframe+0x49/0xbe [ 46.082707][ T7744] ? __lock_acquire+0x548/0x3fb0 [ 46.087621][ T7744] ? prepare_exec_creds+0x12/0xf0 [ 46.092620][ T7744] ? __do_execve_file.isra.0+0x393/0x23f0 [ 46.098310][ T7744] ? __x64_sys_execve+0x8f/0xc0 [ 46.103138][ T7744] do_filp_open+0x1a1/0x280 [ 46.107612][ T7744] ? may_open_dev+0x100/0x100 [ 46.112271][ T7744] ? __lock_acquire+0x548/0x3fb0 [ 46.117212][ T7744] do_open_execat+0x137/0x690 [ 46.121862][ T7744] ? unregister_binfmt+0x170/0x170 [ 46.126948][ T7744] ? lock_downgrade+0x880/0x880 [ 46.131771][ T7744] ? __sanitizer_cov_trace_const_cmp4+0x16/0x20 [ 46.137985][ T7744] ? kasan_check_read+0x11/0x20 [ 46.142809][ T7744] ? do_raw_spin_unlock+0x57/0x270 [ 46.147899][ T7744] __do_execve_file.isra.0+0x178d/0x23f0 [ 46.153503][ T7744] ? __sanitizer_cov_trace_cmp8+0x18/0x20 [ 46.159191][ T7744] ? __check_object_size+0x3d/0x42f [ 46.164366][ T7744] ? copy_strings_kernel+0x110/0x110 [ 46.169624][ T7744] ? __sanitizer_cov_trace_const_cmp4+0x16/0x20 [ 46.175855][ T7744] ? getname_flags+0x277/0x5b0 [ 46.180602][ T7744] ? entry_SYSCALL_64_after_hwframe+0x49/0xbe [ 46.186645][ T7744] __x64_sys_execve+0x8f/0xc0 [ 46.191298][ T7744] do_syscall_64+0x103/0x610 [ 46.195864][ T7744] entry_SYSCALL_64_after_hwframe+0x49/0xbe [ 46.201730][ T7744] RIP: 0033:0x4402a9 [ 46.205598][ T7744] 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 [ 46.225176][ T7744] RSP: 002b:00007ffcdd9d7c28 EFLAGS: 00000246 ORIG_RAX: 000000000000003b [ 46.233577][ T7744] RAX: ffffffffffffffda RBX: 00000000004002c8 RCX: 00000000004402a9 [ 46.241534][ T7744] RDX: 0000000000000000 RSI: 0000000000000000 RDI: 0000000020000480 [ 46.249483][ T7744] RBP: 00000000006ca018 R08: 0000000000000000 R09: 0000000000000000 [ 46.257431][ T7744] R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000401b30 [ 46.265377][ T7744] R13: 0000000000401bc0 R14: 0000000000000000 R15: 0000000000000000