[ 37.229181] audit: type=1800 audit(1547240511.724:26): pid=7696 uid=0 auid=4294967295 ses=4294967295 subj==unconfined op=collect_data cause=failed(directio) comm="startpar" name="mcstrans" dev="sda1" ino=2457 res=0 [ 37.253344] audit: type=1800 audit(1547240511.724:27): pid=7696 uid=0 auid=4294967295 ses=4294967295 subj==unconfined op=collect_data cause=failed(directio) comm="startpar" name="restorecond" dev="sda1" ino=2436 res=0 [ 37.284897] audit: type=1800 audit(1547240511.724:28): pid=7696 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. [ 37.918266] audit: type=1800 audit(1547240512.434:29): pid=7696 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 '10.128.0.119' (ECDSA) to the list of known hosts. executing program syzkaller login: [ 49.274185] [ 49.275868] ====================================================== [ 49.282164] WARNING: possible circular locking dependency detected [ 49.288459] 5.0.0-rc1+ #20 Not tainted [ 49.292316] ------------------------------------------------------ [ 49.298607] syz-executor934/7848 is trying to acquire lock: [ 49.304310] 00000000ab194465 (&pipe->mutex/1){+.+.}, at: fifo_open+0x159/0xb00 [ 49.311658] [ 49.311658] but task is already holding lock: [ 49.317605] 00000000f1c2e523 (&sig->cred_guard_mutex){+.+.}, at: __do_execve_file.isra.0+0x45d/0x2700 [ 49.326952] [ 49.326952] which lock already depends on the new lock. [ 49.326952] [ 49.335245] [ 49.335245] the existing dependency chain (in reverse order) is: [ 49.343119] [ 49.343119] -> #1 (&sig->cred_guard_mutex){+.+.}: [ 49.349432] __mutex_lock+0x12f/0x1670 [ 49.353826] mutex_lock_interruptible_nested+0x16/0x20 [ 49.359599] proc_pid_attr_write+0x1fa/0x530 [ 49.364516] __vfs_write+0x116/0xb40 [ 49.368738] __kernel_write+0x110/0x3b0 [ 49.373232] write_pipe_buf+0x180/0x240 [ 49.377706] __splice_from_pipe+0x39a/0x7e0 [ 49.382536] splice_from_pipe+0x1ea/0x310 [ 49.387183] default_file_splice_write+0x3c/0x90 [ 49.392436] do_splice+0x64b/0x1410 [ 49.396575] __x64_sys_splice+0x2c6/0x330 [ 49.401226] do_syscall_64+0x1a3/0x800 [ 49.405617] entry_SYSCALL_64_after_hwframe+0x49/0xbe [ 49.411317] [ 49.411317] -> #0 (&pipe->mutex/1){+.+.}: [ 49.417347] lock_acquire+0x1db/0x570 [ 49.421650] __mutex_lock+0x12f/0x1670 [ 49.426056] mutex_lock_nested+0x16/0x20 [ 49.430625] fifo_open+0x159/0xb00 [ 49.434665] do_dentry_open+0x48a/0x1210 [ 49.439228] vfs_open+0xa0/0xd0 [ 49.443011] path_openat+0x144f/0x5650 [ 49.447395] do_filp_open+0x26f/0x370 [ 49.451696] do_open_execat+0x20e/0x930 [ 49.456186] __do_execve_file.isra.0+0x1966/0x2700 [ 49.461624] __x64_sys_execve+0x8f/0xc0 [ 49.466103] do_syscall_64+0x1a3/0x800 [ 49.470518] entry_SYSCALL_64_after_hwframe+0x49/0xbe [ 49.476203] [ 49.476203] other info that might help us debug this: [ 49.476203] [ 49.484317] Possible unsafe locking scenario: [ 49.484317] [ 49.490346] CPU0 CPU1 [ 49.494993] ---- ---- [ 49.499634] lock(&sig->cred_guard_mutex); [ 49.503935] lock(&pipe->mutex/1); [ 49.510057] lock(&sig->cred_guard_mutex); [ 49.516894] lock(&pipe->mutex/1); [ 49.520514] [ 49.520514] *** DEADLOCK *** [ 49.520514] [ 49.526552] 1 lock held by syz-executor934/7848: [ 49.531284] #0: 00000000f1c2e523 (&sig->cred_guard_mutex){+.+.}, at: __do_execve_file.isra.0+0x45d/0x2700 [ 49.541079] [ 49.541079] stack backtrace: [ 49.545553] CPU: 0 PID: 7848 Comm: syz-executor934 Not tainted 5.0.0-rc1+ #20 [ 49.552802] Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 [ 49.562131] Call Trace: [ 49.564847] dump_stack+0x1db/0x2d0 [ 49.568456] ? dump_stack_print_info.cold+0x20/0x20 [ 49.573451] ? print_stack_trace+0x77/0xb0 [ 49.577664] ? vprintk_func+0x86/0x189 [ 49.581532] print_circular_bug.isra.0.cold+0x1cc/0x28f [ 49.586882] __lock_acquire+0x3014/0x4a30 [ 49.591010] ? is_bpf_text_address+0xac/0x170 [ 49.595487] ? mark_held_locks+0x100/0x100 [ 49.599700] ? mark_held_locks+0xb1/0x100 [ 49.603831] ? _raw_spin_unlock_irqrestore+0x6b/0xe0 [ 49.608913] ? lockdep_hardirqs_on+0x415/0x5d0 [ 49.613492] ? trace_hardirqs_off_caller+0x300/0x300 [ 49.618578] ? do_raw_spin_trylock+0x270/0x270 [ 49.623163] ? add_lock_to_list.isra.0+0x450/0x450 [ 49.628095] ? print_usage_bug+0xd0/0xd0 [ 49.632147] ? __lock_is_held+0xb6/0x140 [ 49.636191] lock_acquire+0x1db/0x570 [ 49.639974] ? fifo_open+0x159/0xb00 [ 49.643669] ? ___might_sleep+0x1e7/0x310 [ 49.647897] ? lock_release+0xc40/0xc40 [ 49.651870] ? fifo_open+0x159/0xb00 [ 49.655574] ? fifo_open+0x159/0xb00 [ 49.659279] __mutex_lock+0x12f/0x1670 [ 49.663153] ? fifo_open+0x159/0xb00 [ 49.666865] ? __sanitizer_cov_trace_const_cmp4+0x16/0x20 [ 49.672382] ? fifo_open+0x159/0xb00 [ 49.676090] ? check_preemption_disabled+0x48/0x290 [ 49.681089] ? lockdep_init_map+0x10c/0x5b0 [ 49.685388] ? mutex_trylock+0x2d0/0x2d0 [ 49.689431] ? add_lock_to_list.isra.0+0x450/0x450 [ 49.694338] ? __mutex_init+0x1f6/0x2a0 [ 49.698292] ? psi_task_change.cold+0x1ec/0x1ec [ 49.702943] ? fifo_open+0x2b5/0xb00 [ 49.706653] ? find_held_lock+0x35/0x120 [ 49.710697] ? fifo_open+0x2b5/0xb00 [ 49.714390] ? lock_acquire+0x1db/0x570 [ 49.718345] ? kasan_check_read+0x11/0x20 [ 49.722482] ? do_raw_spin_unlock+0xa0/0x330 [ 49.726875] ? do_raw_spin_trylock+0x270/0x270 [ 49.731437] mutex_lock_nested+0x16/0x20 [ 49.735476] ? _raw_spin_unlock+0x2d/0x50 [ 49.739606] ? mutex_lock_nested+0x16/0x20 [ 49.743822] fifo_open+0x159/0xb00 [ 49.747346] do_dentry_open+0x48a/0x1210 [ 49.751399] ? pipe_release+0x280/0x280 [ 49.755363] ? chown_common+0x740/0x740 [ 49.759319] ? security_inode_permission+0xd5/0x110 [ 49.764328] ? inode_permission+0xb4/0x570 [ 49.768546] vfs_open+0xa0/0xd0 [ 49.771808] path_openat+0x144f/0x5650 [ 49.775678] ? is_bpf_text_address+0xd3/0x170 [ 49.780158] ? path_lookupat.isra.0+0xba0/0xba0 [ 49.784895] ? __lock_acquire+0x572/0x4a30 [ 49.789115] ? kmem_cache_alloc+0x12d/0x710 [ 49.793427] ? __do_execve_file.isra.0+0x47a/0x2700 [ 49.798432] ? __x64_sys_execve+0x8f/0xc0 [ 49.802559] ? do_syscall_64+0x1a3/0x800 [ 49.806605] ? entry_SYSCALL_64_after_hwframe+0x49/0xbe [ 49.811976] ? add_lock_to_list.isra.0+0x450/0x450 [ 49.816903] do_filp_open+0x26f/0x370 [ 49.820688] ? may_open_dev+0x100/0x100 [ 49.824664] ? refcount_add_not_zero_checked+0x330/0x330 [ 49.830101] ? prepare_creds+0xa4/0x4e0 [ 49.834057] ? add_lock_to_list.isra.0+0x450/0x450 [ 49.838987] ? add_lock_to_list.isra.0+0x450/0x450 [ 49.843906] ? __do_execve_file.isra.0+0x901/0x2700 [ 49.848934] do_open_execat+0x20e/0x930 [ 49.852892] ? unregister_binfmt+0x2b0/0x2b0 [ 49.857280] ? kasan_check_read+0x11/0x20 [ 49.861407] ? do_raw_spin_trylock+0x270/0x270 [ 49.865970] ? __phys_addr_symbol+0x30/0x70 [ 49.870275] __do_execve_file.isra.0+0x1966/0x2700 [ 49.875186] ? rcu_pm_notify+0xd0/0xd0 [ 49.879052] ? copy_strings_kernel+0x110/0x110 [ 49.883615] ? __sanitizer_cov_trace_const_cmp8+0x18/0x20 [ 49.889132] ? strncpy_from_user+0x3aa/0x4e0 [ 49.893518] ? digsig_verify.cold+0x32/0x32 [ 49.897841] ? kmem_cache_alloc+0x341/0x710 [ 49.902147] ? do_syscall_64+0x8c/0x800 [ 49.906101] ? __sanitizer_cov_trace_const_cmp4+0x16/0x20 [ 49.911618] ? getname_flags+0x277/0x5b0 [ 49.915658] ? trace_hardirqs_off_caller+0x300/0x300 [ 49.920742] __x64_sys_execve+0x8f/0xc0 [ 49.924695] do_syscall_64+0x1a3/0x800 [ 49.928569] ? syscall_return_slowpath+0x5f0/0x5f0 [ 49.933479] ? prepare_exit_to_usermode+0x232/0x3b0 [ 49.938477] ? trace_hardirqs_off_thunk+0x1a/0x1c [ 49.943312] entry_SYSCALL_64_after_hwframe+0x49/0xbe [ 49.948482] RIP: 0033:0x440139 [ 49.951655] 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 [ 49.970550] RSP: 002b:00007ffdba6d2118 EFLAGS: 00000217 ORIG_RAX: 000000000000003b [ 49.978273] RAX: ffffffffffffffda RBX: 0030656c69662f2e RCX: 0000000000440139 [ 49.985534] RDX: 0000000000000000 RSI: 0000000000000000 RDI: 0000000020000240 [ 49.992789] RBP: 00000000006ca018 R08: 0000000000000000 R09: 0000000000000000 [ 50.000048] R10: 0000000000000000 R11: 0000000000000217 R12: 00000000004019c0 [ 50.007316] R13: 0000000000401a50 R14: 0000000000000000 R15: 0000000000000000