[ 39.707531] audit: type=1800 audit(1546948097.165:25): pid=7836 uid=0 auid=4294967295 ses=4294967295 subj==unconfined op=collect_data cause=failed(directio) comm="startpar" name="cron" dev="sda1" ino=2414 res=0 [ 39.744140] audit: type=1800 audit(1546948097.175:26): pid=7836 uid=0 auid=4294967295 ses=4294967295 subj==unconfined op=collect_data cause=failed(directio) comm="startpar" name="mcstrans" dev="sda1" ino=2457 res=0 [ 39.772661] audit: type=1800 audit(1546948097.175:27): pid=7836 uid=0 auid=4294967295 ses=4294967295 subj==unconfined op=collect_data cause=failed(directio) comm="startpar" name="restorecond" dev="sda1" ino=2436 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. [....] startpar: service(s) returned failure: rsyslog ssh ...[?25l[?1c7[FAIL8[?25h[?0c failed! Debian GNU/Linux 7 syzkaller ttyS0 Warning: Permanently added '10.128.0.120' (ECDSA) to the list of known hosts. executing program syzkaller login: [ 49.445751] [ 49.447395] ====================================================== [ 49.453686] WARNING: possible circular locking dependency detected [ 49.459981] 5.0.0-rc1+ #14 Not tainted [ 49.463839] ------------------------------------------------------ [ 49.470131] syz-executor242/8011 is trying to acquire lock: [ 49.475817] 00000000e36c1c58 (&pipe->mutex/1){+.+.}, at: fifo_open+0x159/0xb00 [ 49.483165] [ 49.483165] but task is already holding lock: [ 49.489112] 000000005c1b1ce8 (&sig->cred_guard_mutex){+.+.}, at: __do_execve_file.isra.0+0x45d/0x2700 [ 49.498469] [ 49.498469] which lock already depends on the new lock. [ 49.498469] [ 49.506757] [ 49.506757] the existing dependency chain (in reverse order) is: [ 49.514359] [ 49.514359] -> #1 (&sig->cred_guard_mutex){+.+.}: [ 49.520669] __mutex_lock+0x12f/0x1670 [ 49.525060] mutex_lock_interruptible_nested+0x16/0x20 [ 49.530839] proc_pid_attr_write+0x1fa/0x530 [ 49.535752] __vfs_write+0x116/0xb40 [ 49.539968] __kernel_write+0x110/0x3b0 [ 49.544443] write_pipe_buf+0x180/0x240 [ 49.548921] __splice_from_pipe+0x39a/0x7e0 [ 49.553744] splice_from_pipe+0x1ea/0x310 [ 49.558391] default_file_splice_write+0x3c/0x90 [ 49.563647] do_splice+0x64b/0x1410 [ 49.567773] __x64_sys_splice+0x2c6/0x330 [ 49.572422] do_syscall_64+0x1a3/0x800 [ 49.576809] entry_SYSCALL_64_after_hwframe+0x49/0xbe [ 49.582497] [ 49.582497] -> #0 (&pipe->mutex/1){+.+.}: [ 49.588106] lock_acquire+0x1db/0x570 [ 49.592408] __mutex_lock+0x12f/0x1670 [ 49.596797] mutex_lock_nested+0x16/0x20 [ 49.601372] fifo_open+0x159/0xb00 [ 49.605410] do_dentry_open+0x48a/0x1210 [ 49.609967] vfs_open+0xa0/0xd0 [ 49.613751] path_openat+0x144f/0x5650 [ 49.618133] do_filp_open+0x26f/0x370 [ 49.622431] do_open_execat+0x20e/0x930 [ 49.626906] __do_execve_file.isra.0+0x1966/0x2700 [ 49.632344] __x64_sys_execve+0x8f/0xc0 [ 49.636839] do_syscall_64+0x1a3/0x800 [ 49.641225] entry_SYSCALL_64_after_hwframe+0x49/0xbe [ 49.646922] [ 49.646922] other info that might help us debug this: [ 49.646922] [ 49.655035] Possible unsafe locking scenario: [ 49.655035] [ 49.661066] CPU0 CPU1 [ 49.665707] ---- ---- [ 49.670356] lock(&sig->cred_guard_mutex); [ 49.674650] lock(&pipe->mutex/1); [ 49.680771] lock(&sig->cred_guard_mutex); [ 49.687581] lock(&pipe->mutex/1); [ 49.691184] [ 49.691184] *** DEADLOCK *** [ 49.691184] [ 49.697216] 1 lock held by syz-executor242/8011: [ 49.701942] #0: 000000005c1b1ce8 (&sig->cred_guard_mutex){+.+.}, at: __do_execve_file.isra.0+0x45d/0x2700 [ 49.711721] [ 49.711721] stack backtrace: [ 49.716192] CPU: 0 PID: 8011 Comm: syz-executor242 Not tainted 5.0.0-rc1+ #14 [ 49.723438] Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 [ 49.732768] Call Trace: [ 49.735355] dump_stack+0x1db/0x2d0 [ 49.738978] ? dump_stack_print_info.cold+0x20/0x20 [ 49.743993] ? print_stack_trace+0x77/0xb0 [ 49.748211] ? vprintk_func+0x86/0x189 [ 49.752094] print_circular_bug.isra.0.cold+0x1cc/0x28f [ 49.757439] __lock_acquire+0x3014/0x4a30 [ 49.761569] ? add_lock_to_list.isra.0+0x450/0x450 [ 49.766477] ? is_bpf_text_address+0xac/0x170 [ 49.770951] ? mark_held_locks+0x100/0x100 [ 49.775172] ? mark_held_locks+0xb1/0x100 [ 49.779299] ? _raw_spin_unlock_irqrestore+0x6b/0xe0 [ 49.784383] ? _raw_spin_unlock_irqrestore+0x6b/0xe0 [ 49.789462] ? lockdep_hardirqs_on+0x415/0x5d0 [ 49.794053] ? trace_hardirqs_off_caller+0x300/0x300 [ 49.799130] ? do_raw_spin_trylock+0x270/0x270 [ 49.803692] ? add_lock_to_list.isra.0+0x450/0x450 [ 49.808597] ? print_usage_bug+0xd0/0xd0 [ 49.812639] ? _raw_spin_unlock_irqrestore+0xa4/0xe0 [ 49.817724] ? __lock_is_held+0xb6/0x140 [ 49.821764] lock_acquire+0x1db/0x570 [ 49.825541] ? fifo_open+0x159/0xb00 [ 49.829243] ? ___might_sleep+0x1e7/0x310 [ 49.833375] ? lock_release+0xc40/0xc40 [ 49.837328] ? fifo_open+0x159/0xb00 [ 49.841030] ? fifo_open+0x159/0xb00 [ 49.844718] __mutex_lock+0x12f/0x1670 [ 49.848598] ? fifo_open+0x159/0xb00 [ 49.852292] ? __sanitizer_cov_trace_const_cmp4+0x16/0x20 [ 49.857805] ? fifo_open+0x159/0xb00 [ 49.861502] ? check_preemption_disabled+0x48/0x290 [ 49.866497] ? lockdep_init_map+0x10c/0x5b0 [ 49.870809] ? mutex_trylock+0x2d0/0x2d0 [ 49.874865] ? add_lock_to_list.isra.0+0x450/0x450 [ 49.879772] ? __mutex_init+0x1f6/0x2a0 [ 49.883741] ? psi_task_change.cold+0x1ec/0x1ec [ 49.888391] ? fifo_open+0x2b5/0xb00 [ 49.892085] ? find_held_lock+0x35/0x120 [ 49.896122] ? fifo_open+0x2b5/0xb00 [ 49.899810] ? lock_acquire+0x1db/0x570 [ 49.903766] ? kasan_check_read+0x11/0x20 [ 49.907891] ? do_raw_spin_unlock+0xa0/0x330 [ 49.912280] ? do_raw_spin_trylock+0x270/0x270 [ 49.916840] mutex_lock_nested+0x16/0x20 [ 49.920883] ? _raw_spin_unlock+0x2d/0x50 [ 49.925007] ? mutex_lock_nested+0x16/0x20 [ 49.929220] fifo_open+0x159/0xb00 [ 49.932763] do_dentry_open+0x48a/0x1210 [ 49.936801] ? pipe_release+0x280/0x280 [ 49.940755] ? chown_common+0x740/0x740 [ 49.944710] ? security_inode_permission+0xd5/0x110 [ 49.949707] ? inode_permission+0xb4/0x570 [ 49.953948] vfs_open+0xa0/0xd0 [ 49.957209] path_openat+0x144f/0x5650 [ 49.961076] ? is_bpf_text_address+0xd3/0x170 [ 49.965569] ? path_lookupat.isra.0+0xba0/0xba0 [ 49.970221] ? __lock_acquire+0x572/0x4a30 [ 49.974448] ? kmem_cache_alloc+0x12d/0x710 [ 49.978764] ? __do_execve_file.isra.0+0x47a/0x2700 [ 49.983756] ? __x64_sys_execve+0x8f/0xc0 [ 49.987885] ? do_syscall_64+0x1a3/0x800 [ 49.991924] ? entry_SYSCALL_64_after_hwframe+0x49/0xbe [ 49.997264] ? add_lock_to_list.isra.0+0x450/0x450 [ 50.002171] do_filp_open+0x26f/0x370 [ 50.005950] ? may_open_dev+0x100/0x100 [ 50.009938] ? refcount_add_not_zero_checked+0x330/0x330 [ 50.015375] ? prepare_creds+0xa4/0x4e0 [ 50.019334] ? add_lock_to_list.isra.0+0x450/0x450 [ 50.024270] ? add_lock_to_list.isra.0+0x450/0x450 [ 50.029175] ? __do_execve_file.isra.0+0x901/0x2700 [ 50.034185] do_open_execat+0x20e/0x930 [ 50.038140] ? unregister_binfmt+0x2b0/0x2b0 [ 50.042526] ? kasan_check_read+0x11/0x20 [ 50.046664] ? do_raw_spin_trylock+0x270/0x270 [ 50.051230] ? __phys_addr_symbol+0x30/0x70 [ 50.055548] __do_execve_file.isra.0+0x1966/0x2700 [ 50.060459] ? copy_strings_kernel+0x110/0x110 [ 50.065025] ? __sanitizer_cov_trace_const_cmp8+0x18/0x20 [ 50.070541] ? strncpy_from_user+0x3aa/0x4e0 [ 50.074941] ? digsig_verify.cold+0x32/0x32 [ 50.079249] ? kmem_cache_alloc+0x341/0x710 [ 50.083556] ? do_syscall_64+0x8c/0x800 [ 50.087510] ? lockdep_hardirqs_on+0x415/0x5d0 [ 50.092070] ? __sanitizer_cov_trace_const_cmp4+0x16/0x20 [ 50.097583] ? getname_flags+0x277/0x5b0 [ 50.101622] ? trace_hardirqs_off_caller+0x300/0x300 [ 50.106701] __x64_sys_execve+0x8f/0xc0 [ 50.110657] do_syscall_64+0x1a3/0x800 [ 50.114524] ? syscall_return_slowpath+0x5f0/0x5f0 [ 50.119435] ? prepare_exit_to_usermode+0x3b0/0x3b0 [ 50.124427] ? __switch_to_asm+0x34/0x70 [ 50.128466] ? trace_hardirqs_off_thunk+0x1a/0x1c [ 50.133291] entry_SYSCALL_64_after_hwframe+0x49/0xbe [ 50.138454] RIP: 0033:0x445709 [ 50.141627] Code: e8 ec b8 02 00 48 83 c4 18 c3 0f 1f 80 00 00 00 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 8b 12 fc ff c3 66 2e 0f 1f 84 00 00 00 00 [ 50.160521] RSP: 002b:00007f0295c5bd18 EFLAGS: 00000246 ORIG_RAX: 000000000000003b [ 50.168204] RAX: ffffffffffffffda RBX: 00000000006dac58 RCX: 0000000000445709 [ 50.175450] RDX: 0000000000000000 RSI: 0000000000000000 RDI: 0000000020000040 [ 50.182880] RBP: 00000000006dac50 R08: 68742f636f72702f R09: 68742f636f72702f [ 50.190128] R10: 0000000000000000 R11: 0000000000000246 R12: 00000000006dac5c [ 50.197415] R13: