[ 35.897313][ T26] audit: type=1800 audit(1552758381.603:26): pid=7504 uid=0 auid=4294967295 ses=4294967295 subj==unconfined op=collect_data cause=failed(directio) comm="startpar" name="mcstrans" dev="sda1" ino=2457 res=0 [ 35.933686][ T26] audit: type=1800 audit(1552758381.603:27): pid=7504 uid=0 auid=4294967295 ses=4294967295 subj==unconfined op=collect_data cause=failed(directio) comm="startpar" name="restorecond" dev="sda1" ino=2436 res=0 [ 35.960695][ T26] audit: type=1800 audit(1552758381.603:28): pid=7504 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. [ 36.666982][ T26] audit: type=1800 audit(1552758382.413:29): pid=7504 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 Warning: Permanently added '10.128.0.230' (ECDSA) to the list of known hosts. executing program syzkaller login: [ 46.508956][ T7656] [ 46.511506][ T7656] ====================================================== [ 46.518623][ T7656] WARNING: possible circular locking dependency detected [ 46.525627][ T7656] 5.0.0+ #25 Not tainted [ 46.529841][ T7656] ------------------------------------------------------ [ 46.536845][ T7656] syz-executor872/7656 is trying to acquire lock: [ 46.543272][ T7656] 000000004043a2c2 (&pipe->mutex/1){+.+.}, at: fifo_open+0x159/0xb00 [ 46.551346][ T7656] [ 46.551346][ T7656] but task is already holding lock: [ 46.558698][ T7656] 000000008cd1441a (&sig->cred_guard_mutex){+.+.}, at: __do_execve_file.isra.0+0x376/0x23f0 [ 46.568843][ T7656] [ 46.568843][ T7656] which lock already depends on the new lock. [ 46.568843][ T7656] [ 46.579237][ T7656] [ 46.579237][ T7656] the existing dependency chain (in reverse order) is: [ 46.588337][ T7656] [ 46.588337][ T7656] -> #1 (&sig->cred_guard_mutex){+.+.}: [ 46.596047][ T7656] lock_acquire+0x16f/0x3f0 [ 46.601053][ T7656] __mutex_lock+0xf7/0x1310 [ 46.606065][ T7656] mutex_lock_interruptible_nested+0x16/0x20 [ 46.612640][ T7656] proc_pid_attr_write+0x200/0x580 [ 46.618288][ T7656] __vfs_write+0x8d/0x110 [ 46.623119][ T7656] __kernel_write+0x110/0x3b0 [ 46.628713][ T7656] write_pipe_buf+0x15d/0x1f0 [ 46.633893][ T7656] __splice_from_pipe+0x395/0x7d0 [ 46.639451][ T7656] splice_from_pipe+0x108/0x170 [ 46.644805][ T7656] default_file_splice_write+0x3c/0x90 [ 46.650882][ T7656] do_splice+0x70a/0x13c0 [ 46.655736][ T7656] __ia32_sys_splice+0x2c4/0x330 [ 46.661195][ T7656] do_fast_syscall_32+0x281/0xc98 [ 46.666727][ T7656] entry_SYSENTER_compat+0x70/0x7f [ 46.672422][ T7656] [ 46.672422][ T7656] -> #0 (&pipe->mutex/1){+.+.}: [ 46.679613][ T7656] __lock_acquire+0x239c/0x3fb0 [ 46.684990][ T7656] lock_acquire+0x16f/0x3f0 [ 46.689999][ T7656] __mutex_lock+0xf7/0x1310 [ 46.695005][ T7656] mutex_lock_nested+0x16/0x20 [ 46.700269][ T7656] fifo_open+0x159/0xb00 [ 46.705009][ T7656] do_dentry_open+0x488/0x1160 [ 46.710298][ T7656] vfs_open+0xa0/0xd0 [ 46.714804][ T7656] path_openat+0x10e9/0x46e0 [ 46.719915][ T7656] do_filp_open+0x1a1/0x280 [ 46.724922][ T7656] do_open_execat+0x137/0x690 [ 46.730125][ T7656] __do_execve_file.isra.0+0x178d/0x23f0 [ 46.736272][ T7656] __ia32_compat_sys_execve+0x94/0xc0 [ 46.742151][ T7656] do_fast_syscall_32+0x281/0xc98 [ 46.747677][ T7656] entry_SYSENTER_compat+0x70/0x7f [ 46.753311][ T7656] [ 46.753311][ T7656] other info that might help us debug this: [ 46.753311][ T7656] [ 46.763526][ T7656] Possible unsafe locking scenario: [ 46.763526][ T7656] [ 46.770963][ T7656] CPU0 CPU1 [ 46.776308][ T7656] ---- ---- [ 46.781680][ T7656] lock(&sig->cred_guard_mutex); [ 46.786691][ T7656] lock(&pipe->mutex/1); [ 46.793532][ T7656] lock(&sig->cred_guard_mutex); [ 46.801140][ T7656] lock(&pipe->mutex/1); [ 46.805452][ T7656] [ 46.805452][ T7656] *** DEADLOCK *** [ 46.805452][ T7656] [ 46.813580][ T7656] 1 lock held by syz-executor872/7656: [ 46.819123][ T7656] #0: 000000008cd1441a (&sig->cred_guard_mutex){+.+.}, at: __do_execve_file.isra.0+0x376/0x23f0 [ 46.829705][ T7656] [ 46.829705][ T7656] stack backtrace: [ 46.835606][ T7656] CPU: 0 PID: 7656 Comm: syz-executor872 Not tainted 5.0.0+ #25 [ 46.843211][ T7656] Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 [ 46.853354][ T7656] Call Trace: [ 46.856660][ T7656] dump_stack+0x172/0x1f0 [ 46.861160][ T7656] print_circular_bug.isra.0.cold+0x1cc/0x28f [ 46.867216][ T7656] check_prev_add.constprop.0+0xf11/0x23c0 [ 46.873032][ T7656] ? depot_save_stack+0x1de/0x460 [ 46.878155][ T7656] ? check_usage+0x570/0x570 [ 46.882734][ T7656] ? mark_held_locks+0xa4/0xf0 [ 46.887589][ T7656] ? _raw_spin_unlock_irqrestore+0x6b/0xe0 [ 46.893378][ T7656] ? graph_lock+0x7b/0x200 [ 46.897938][ T7656] ? __lockdep_reset_lock+0x450/0x450 [ 46.903291][ T7656] ? __sanitizer_cov_trace_const_cmp8+0x18/0x20 [ 46.909514][ T7656] __lock_acquire+0x239c/0x3fb0 [ 46.914347][ T7656] ? save_stack+0xa9/0xd0 [ 46.918662][ T7656] ? mark_held_locks+0xf0/0xf0 [ 46.923494][ T7656] lock_acquire+0x16f/0x3f0 [ 46.927983][ T7656] ? fifo_open+0x159/0xb00 [ 46.932382][ T7656] ? fifo_open+0x159/0xb00 [ 46.936781][ T7656] __mutex_lock+0xf7/0x1310 [ 46.941265][ T7656] ? fifo_open+0x159/0xb00 [ 46.946354][ T7656] ? fifo_open+0x159/0xb00 [ 46.950782][ T7656] ? fifo_open+0x2b5/0xb00 [ 46.955186][ T7656] ? mutex_trylock+0x1e0/0x1e0 [ 46.959928][ T7656] ? fifo_open+0x2b5/0xb00 [ 46.964327][ T7656] ? kasan_check_write+0x14/0x20 [ 46.969248][ T7656] ? lock_downgrade+0x880/0x880 [ 46.974081][ T7656] mutex_lock_nested+0x16/0x20 [ 46.978866][ T7656] ? mutex_lock_nested+0x16/0x20 [ 46.983820][ T7656] fifo_open+0x159/0xb00 [ 46.988060][ T7656] do_dentry_open+0x488/0x1160 [ 46.992918][ T7656] ? pipe_release+0x280/0x280 [ 46.997671][ T7656] ? chown_common+0x5c0/0x5c0 [ 47.002322][ T7656] ? inode_permission+0xb4/0x570 [ 47.007675][ T7656] vfs_open+0xa0/0xd0 [ 47.011634][ T7656] path_openat+0x10e9/0x46e0 [ 47.016304][ T7656] ? path_lookupat.isra.0+0x8d0/0x8d0 [ 47.022088][ T7656] ? __kmalloc+0x15c/0x740 [ 47.026500][ T7656] ? prepare_creds+0x2f5/0x3f0 [ 47.031251][ T7656] ? prepare_exec_creds+0x12/0xf0 [ 47.036262][ T7656] ? __do_execve_file.isra.0+0x393/0x23f0 [ 47.041971][ T7656] ? do_fast_syscall_32+0x281/0xc98 [ 47.047259][ T7656] ? entry_SYSENTER_compat+0x70/0x7f [ 47.052534][ T7656] ? __lock_acquire+0x548/0x3fb0 [ 47.057585][ T7656] ? prepare_exec_creds+0x12/0xf0 [ 47.062608][ T7656] ? __do_execve_file.isra.0+0x393/0x23f0 [ 47.068307][ T7656] ? __ia32_compat_sys_execve+0x94/0xc0 [ 47.073841][ T7656] do_filp_open+0x1a1/0x280 [ 47.078364][ T7656] ? may_open_dev+0x100/0x100 [ 47.083051][ T7656] ? __lock_acquire+0x548/0x3fb0 [ 47.087976][ T7656] do_open_execat+0x137/0x690 [ 47.092641][ T7656] ? unregister_binfmt+0x170/0x170 [ 47.097736][ T7656] ? lock_downgrade+0x880/0x880 [ 47.102571][ T7656] ? __sanitizer_cov_trace_const_cmp4+0x16/0x20 [ 47.108823][ T7656] ? kasan_check_read+0x11/0x20 [ 47.113658][ T7656] ? do_raw_spin_unlock+0x57/0x270 [ 47.118785][ T7656] __do_execve_file.isra.0+0x178d/0x23f0 [ 47.124409][ T7656] ? __sanitizer_cov_trace_cmp8+0x18/0x20 [ 47.130299][ T7656] ? __check_object_size+0x3d/0x42f [ 47.135496][ T7656] ? copy_strings_kernel+0x110/0x110 [ 47.140762][ T7656] ? __sanitizer_cov_trace_const_cmp4+0x16/0x20 [ 47.147012][ T7656] ? getname_flags+0x277/0x5b0 [ 47.151776][ T7656] ? entry_SYSENTER_compat+0x70/0x7f [ 47.157153][ T7656] __ia32_compat_sys_execve+0x94/0xc0 [ 47.162776][ T7656] do_fast_syscall_32+0x281/0xc98 [ 47.167815][ T7656] entry_SYSENTER_compat+0x70/0x7f [ 47.172932][ T7656] RIP: 0023:0xf7f8f869 [ 47.178017][ T7656] Code: 85 d2 74 02 89 0a 5b 5d c3 8b 04 24 c3 8b 14 24 c3 8b 3c 24 c3 90 90 90 90 90 90 90 90 90 90 90 90 51 52 55 89 e5 0f 34 cd 80 <5d> 5a 59 c3 90 90 90 90 eb 0d 90 90 90 90 90 90 90 90 90 90 90 90 [ 47.198268][ T7656] RSP: 002b:00000000ffa9abcc EFLAGS: 00000217 ORIG_RAX: 000000000000000b [ 47.206671][ T7656] RAX: ffffffffffffffda RBX: 0000000020000180 RCX: 0000000000000000 [ 47.214631][ T7656] RDX: 0000000000000000 RSI: 000000000000000e RDI: 0000000020000200 [ 47.222592][ T7656] RBP: 000000000000103f R08: 0000000000000000 R09: 0000000000000000 [ 47.230650][ T7656] R10: 0000000000000000 R11: 0000000000000000 R12: 0000000000000000 [ 47.238784][ T7656] R13: 0000000000000000 R14: 0000000000000000 R15: 0000000000000000