[ 38.690962][ T26] audit: type=1800 audit(1552755291.240:25): pid=7733 uid=0 auid=4294967295 ses=4294967295 subj=_ op=collect_data cause=failed(directio) comm="startpar" name="cron" dev="sda1" ino=2414 res=0 [ 38.711833][ T26] audit: type=1800 audit(1552755291.250:26): pid=7733 uid=0 auid=4294967295 ses=4294967295 subj=_ op=collect_data cause=failed(directio) comm="startpar" name="mcstrans" dev="sda1" ino=2457 res=0 [ 38.804094][ T26] audit: type=1800 audit(1552755291.360:27): pid=7733 uid=0 auid=4294967295 ses=4294967295 subj=_ op=collect_data cause=failed(directio) comm="startpar" name="restorecond" dev="sda1" ino=2436 res=0 [ 38.835611][ T26] audit: type=1800 audit(1552755291.390:28): pid=7733 uid=0 auid=4294967295 ses=4294967295 subj=_ 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. Debian GNU/Linux 7 syzkaller ttyS0 Warning: Permanently added '10.128.10.46' (ECDSA) to the list of known hosts. executing program syzkaller login: [ 48.325685][ T7886] [ 48.328049][ T7886] ====================================================== [ 48.335148][ T7886] WARNING: possible circular locking dependency detected [ 48.342160][ T7886] 5.0.0+ #25 Not tainted [ 48.346416][ T7886] ------------------------------------------------------ [ 48.353582][ T7886] syz-executor585/7886 is trying to acquire lock: [ 48.360153][ T7886] 00000000c12fcced (&pipe->mutex/1){+.+.}, at: fifo_open+0x159/0xb00 [ 48.370359][ T7886] [ 48.370359][ T7886] but task is already holding lock: [ 48.377720][ T7886] 00000000c451ba8a (&sig->cred_guard_mutex){+.+.}, at: __do_execve_file.isra.0+0x376/0x23f0 [ 48.387790][ T7886] [ 48.387790][ T7886] which lock already depends on the new lock. [ 48.387790][ T7886] [ 48.398965][ T7886] [ 48.398965][ T7886] the existing dependency chain (in reverse order) is: [ 48.407980][ T7886] [ 48.407980][ T7886] -> #1 (&sig->cred_guard_mutex){+.+.}: [ 48.415794][ T7886] lock_acquire+0x16f/0x3f0 [ 48.420939][ T7886] __mutex_lock+0xf7/0x1310 [ 48.426676][ T7886] mutex_lock_interruptible_nested+0x16/0x20 [ 48.433186][ T7886] proc_pid_attr_write+0x200/0x580 [ 48.438817][ T7886] __vfs_write+0x8d/0x110 [ 48.444019][ T7886] __kernel_write+0x110/0x3b0 [ 48.449330][ T7886] write_pipe_buf+0x15d/0x1f0 [ 48.458647][ T7886] __splice_from_pipe+0x395/0x7d0 [ 48.464209][ T7886] splice_from_pipe+0x108/0x170 [ 48.469846][ T7886] default_file_splice_write+0x3c/0x90 [ 48.479202][ T7886] do_splice+0x70a/0x13c0 [ 48.484062][ T7886] __x64_sys_splice+0x2c6/0x330 [ 48.489422][ T7886] do_syscall_64+0x103/0x610 [ 48.494539][ T7886] entry_SYSCALL_64_after_hwframe+0x49/0xbe [ 48.501018][ T7886] [ 48.501018][ T7886] -> #0 (&pipe->mutex/1){+.+.}: [ 48.508170][ T7886] __lock_acquire+0x239c/0x3fb0 [ 48.513632][ T7886] lock_acquire+0x16f/0x3f0 [ 48.518665][ T7886] __mutex_lock+0xf7/0x1310 [ 48.523678][ T7886] mutex_lock_nested+0x16/0x20 [ 48.528962][ T7886] fifo_open+0x159/0xb00 [ 48.533739][ T7886] do_dentry_open+0x488/0x1160 [ 48.539029][ T7886] vfs_open+0xa0/0xd0 [ 48.543521][ T7886] path_openat+0x10e9/0x46e0 [ 48.548618][ T7886] do_filp_open+0x1a1/0x280 [ 48.553749][ T7886] do_open_execat+0x137/0x690 [ 48.558936][ T7886] __do_execve_file.isra.0+0x178d/0x23f0 [ 48.565080][ T7886] __x64_sys_execve+0x8f/0xc0 [ 48.571609][ T7886] do_syscall_64+0x103/0x610 [ 48.579574][ T7886] entry_SYSCALL_64_after_hwframe+0x49/0xbe [ 48.585981][ T7886] [ 48.585981][ T7886] other info that might help us debug this: [ 48.585981][ T7886] [ 48.596199][ T7886] Possible unsafe locking scenario: [ 48.596199][ T7886] [ 48.603659][ T7886] CPU0 CPU1 [ 48.609015][ T7886] ---- ---- [ 48.614369][ T7886] lock(&sig->cred_guard_mutex); [ 48.619470][ T7886] lock(&pipe->mutex/1); [ 48.626299][ T7886] lock(&sig->cred_guard_mutex); [ 48.633820][ T7886] lock(&pipe->mutex/1); [ 48.638160][ T7886] [ 48.638160][ T7886] *** DEADLOCK *** [ 48.638160][ T7886] [ 48.646292][ T7886] 1 lock held by syz-executor585/7886: [ 48.651902][ T7886] #0: 00000000c451ba8a (&sig->cred_guard_mutex){+.+.}, at: __do_execve_file.isra.0+0x376/0x23f0 [ 48.662532][ T7886] [ 48.662532][ T7886] stack backtrace: [ 48.669002][ T7886] CPU: 1 PID: 7886 Comm: syz-executor585 Not tainted 5.0.0+ #25 [ 48.676715][ T7886] Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 [ 48.686773][ T7886] Call Trace: [ 48.690076][ T7886] dump_stack+0x172/0x1f0 [ 48.694704][ T7886] print_circular_bug.isra.0.cold+0x1cc/0x28f [ 48.701946][ T7886] check_prev_add.constprop.0+0xf11/0x23c0 [ 48.707750][ T7886] ? depot_save_stack+0x1de/0x460 [ 48.712785][ T7886] ? check_usage+0x570/0x570 [ 48.717396][ T7886] ? mark_held_locks+0xa4/0xf0 [ 48.722393][ T7886] ? _raw_spin_unlock_irqrestore+0x6b/0xe0 [ 48.728299][ T7886] ? graph_lock+0x7b/0x200 [ 48.732895][ T7886] ? __lockdep_reset_lock+0x450/0x450 [ 48.746578][ T7886] ? __sanitizer_cov_trace_const_cmp8+0x18/0x20 [ 48.753306][ T7886] __lock_acquire+0x239c/0x3fb0 [ 48.758870][ T7886] ? save_stack+0xa9/0xd0 [ 48.763396][ T7886] ? mark_held_locks+0xf0/0xf0 [ 48.768159][ T7886] lock_acquire+0x16f/0x3f0 [ 48.773016][ T7886] ? fifo_open+0x159/0xb00 [ 48.777958][ T7886] ? fifo_open+0x159/0xb00 [ 48.782365][ T7886] __mutex_lock+0xf7/0x1310 [ 48.786853][ T7886] ? fifo_open+0x159/0xb00 [ 48.791274][ T7886] ? fifo_open+0x159/0xb00 [ 48.795685][ T7886] ? fifo_open+0x2b5/0xb00 [ 48.800116][ T7886] ? mutex_trylock+0x1e0/0x1e0 [ 48.804869][ T7886] ? fifo_open+0x2b5/0xb00 [ 48.809273][ T7886] ? kasan_check_write+0x14/0x20 [ 48.814200][ T7886] ? lock_downgrade+0x880/0x880 [ 48.819037][ T7886] mutex_lock_nested+0x16/0x20 [ 48.823824][ T7886] ? mutex_lock_nested+0x16/0x20 [ 48.828750][ T7886] fifo_open+0x159/0xb00 [ 48.832996][ T7886] do_dentry_open+0x488/0x1160 [ 48.838096][ T7886] ? pipe_release+0x280/0x280 [ 48.842759][ T7886] ? chown_common+0x5c0/0x5c0 [ 48.848238][ T7886] ? inode_permission+0xb4/0x570 [ 48.853192][ T7886] vfs_open+0xa0/0xd0 [ 48.857159][ T7886] path_openat+0x10e9/0x46e0 [ 48.861730][ T7886] ? path_lookupat.isra.0+0x8d0/0x8d0 [ 48.867189][ T7886] ? __kmalloc+0x15c/0x740 [ 48.871708][ T7886] ? security_prepare_creds+0x123/0x190 [ 48.877236][ T7886] ? prepare_creds+0x2f5/0x3f0 [ 48.881996][ T7886] ? prepare_exec_creds+0x12/0xf0 [ 48.887004][ T7886] ? __do_execve_file.isra.0+0x393/0x23f0 [ 48.893837][ T7886] ? do_syscall_64+0x103/0x610 [ 48.898587][ T7886] ? entry_SYSCALL_64_after_hwframe+0x49/0xbe [ 48.904826][ T7886] ? __lock_acquire+0x548/0x3fb0 [ 48.909748][ T7886] ? prepare_exec_creds+0x12/0xf0 [ 48.914756][ T7886] ? __do_execve_file.isra.0+0x393/0x23f0 [ 48.920456][ T7886] ? __x64_sys_execve+0x8f/0xc0 [ 48.925292][ T7886] do_filp_open+0x1a1/0x280 [ 48.929782][ T7886] ? may_open_dev+0x100/0x100 [ 48.934449][ T7886] ? __lock_acquire+0x548/0x3fb0 [ 48.939389][ T7886] ? lockdep_init_map+0x1be/0x6d0 [ 48.944410][ T7886] do_open_execat+0x137/0x690 [ 48.949072][ T7886] ? unregister_binfmt+0x170/0x170 [ 48.954190][ T7886] ? lock_downgrade+0x880/0x880 [ 48.959087][ T7886] ? __sanitizer_cov_trace_const_cmp4+0x16/0x20 [ 48.965423][ T7886] ? kasan_check_read+0x11/0x20 [ 48.970300][ T7886] ? do_raw_spin_unlock+0x57/0x270 [ 48.975896][ T7886] __do_execve_file.isra.0+0x178d/0x23f0 [ 48.981522][ T7886] ? __sanitizer_cov_trace_cmp8+0x18/0x20 [ 48.987231][ T7886] ? __check_object_size+0x3d/0x42f [ 48.992599][ T7886] ? copy_strings_kernel+0x110/0x110 [ 48.997871][ T7886] ? __sanitizer_cov_trace_const_cmp4+0x16/0x20 [ 49.004099][ T7886] ? getname_flags+0x277/0x5b0 [ 49.008848][ T7886] ? entry_SYSCALL_64_after_hwframe+0x49/0xbe [ 49.015506][ T7886] __x64_sys_execve+0x8f/0xc0 [ 49.020167][ T7886] do_syscall_64+0x103/0x610 [ 49.024736][ T7886] entry_SYSCALL_64_after_hwframe+0x49/0xbe [ 49.030626][ T7886] RIP: 0033:0x440289 [ 49.034512][ T7886] 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 [ 49.055188][ T7886] RSP: 002b:00007ffd8e58d128 EFLAGS: 00000246 ORIG_RAX: 000000000000003b [ 49.070614][ T7886] RAX: ffffffffffffffda RBX: 00000000004002c8 RCX: 0000000000440289 [ 49.079125][ T7886] RDX: 0000000000000000 RSI: 0000000000000000 RDI: 0000000020000180 [ 49.087110][ T7886] RBP: 00000000006ca018 R08: 0000000000000000 R09: 0000000000000000 [ 49.095136][ T7886] R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000401b10 [ 49.103091][ T7886] R13: 0000000000401ba0 R14: 0000000000000000 R15: 0000000000000000