[ 40.275926] audit: type=1800 audit(1546399434.754:25): pid=7957 uid=0 auid=4294967295 ses=4294967295 subj=_ op=collect_data cause=failed(directio) comm="startpar" name="cron" dev="sda1" ino=2414 res=0 [ 40.312632] audit: type=1800 audit(1546399434.754:26): pid=7957 uid=0 auid=4294967295 ses=4294967295 subj=_ op=collect_data cause=failed(directio) comm="startpar" name="mcstrans" dev="sda1" ino=2457 res=0 [ 40.359435] audit: type=1800 audit(1546399434.754:27): pid=7957 uid=0 auid=4294967295 ses=4294967295 subj=_ 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 ...[?25l[?1c7[FAIL8[?25h[?0c failed! Debian GNU/Linux 7 syzkaller ttyS0 Warning: Permanently added '10.128.0.21' (ECDSA) to the list of known hosts. executing program syzkaller login: [ 50.752114] [ 50.753754] ====================================================== [ 50.760043] WARNING: possible circular locking dependency detected [ 50.766352] 4.20.0+ #4 Not tainted [ 50.769862] ------------------------------------------------------ [ 50.776157] syz-executor634/8131 is trying to acquire lock: [ 50.781861] 0000000059cfb049 (&pipe->mutex/1){+.+.}, at: fifo_open+0x159/0xb00 [ 50.789244] [ 50.789244] but task is already holding lock: [ 50.795188] 0000000068cd19e5 (&sig->cred_guard_mutex){+.+.}, at: prepare_bprm_creds+0x55/0x120 [ 50.803921] [ 50.803921] which lock already depends on the new lock. [ 50.803921] [ 50.812235] [ 50.812235] the existing dependency chain (in reverse order) is: [ 50.819834] [ 50.819834] -> #1 (&sig->cred_guard_mutex){+.+.}: [ 50.826155] __mutex_lock+0x12f/0x1670 [ 50.830546] mutex_lock_interruptible_nested+0x16/0x20 [ 50.836334] proc_pid_attr_write+0x1fa/0x530 [ 50.841264] __vfs_write+0x116/0xb40 [ 50.845511] __kernel_write+0x110/0x3b0 [ 50.850002] write_pipe_buf+0x180/0x240 [ 50.854483] __splice_from_pipe+0x39a/0x7e0 [ 50.859321] splice_from_pipe+0x1ea/0x310 [ 50.863991] default_file_splice_write+0x3c/0x90 [ 50.869253] do_splice+0x64b/0x1410 [ 50.873378] __x64_sys_splice+0x2c6/0x330 [ 50.878041] do_syscall_64+0x1a3/0x800 [ 50.882430] entry_SYSCALL_64_after_hwframe+0x49/0xbe [ 50.888124] [ 50.888124] -> #0 (&pipe->mutex/1){+.+.}: [ 50.893745] lock_acquire+0x1db/0x570 [ 50.898054] __mutex_lock+0x12f/0x1670 [ 50.902440] mutex_lock_nested+0x16/0x20 [ 50.907027] fifo_open+0x159/0xb00 [ 50.911100] do_dentry_open+0x48a/0x1210 [ 50.915668] vfs_open+0xa0/0xd0 [ 50.919470] path_openat+0x144f/0x5650 [ 50.923857] do_filp_open+0x26f/0x370 [ 50.928171] do_open_execat+0x20e/0x930 [ 50.932674] __do_execve_file.isra.0+0x181e/0x2510 [ 50.938132] __x64_sys_execve+0x8f/0xc0 [ 50.942608] do_syscall_64+0x1a3/0x800 [ 50.947011] entry_SYSCALL_64_after_hwframe+0x49/0xbe [ 50.952698] [ 50.952698] other info that might help us debug this: [ 50.952698] [ 50.960830] Possible unsafe locking scenario: [ 50.960830] [ 50.966860] CPU0 CPU1 [ 50.971500] ---- ---- [ 50.976169] lock(&sig->cred_guard_mutex); [ 50.980500] lock(&pipe->mutex/1); [ 50.986618] lock(&sig->cred_guard_mutex); [ 50.993431] lock(&pipe->mutex/1); [ 50.997048] [ 50.997048] *** DEADLOCK *** [ 50.997048] [ 51.003090] 1 lock held by syz-executor634/8131: [ 51.007817] #0: 0000000068cd19e5 (&sig->cred_guard_mutex){+.+.}, at: prepare_bprm_creds+0x55/0x120 [ 51.016985] [ 51.016985] stack backtrace: [ 51.021480] CPU: 0 PID: 8131 Comm: syz-executor634 Not tainted 4.20.0+ #4 [ 51.028380] Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 [ 51.038067] Call Trace: [ 51.040636] dump_stack+0x1db/0x2d0 [ 51.044245] ? dump_stack_print_info.cold+0x20/0x20 [ 51.049254] ? print_stack_trace+0x77/0xb0 [ 51.053480] ? vprintk_func+0x86/0x189 [ 51.057348] print_circular_bug.isra.0.cold+0x1cc/0x28f [ 51.062689] __lock_acquire+0x3014/0x4a30 [ 51.066815] ? add_lock_to_list.isra.0+0x450/0x450 [ 51.071724] ? is_bpf_text_address+0xac/0x170 [ 51.076218] ? mark_held_locks+0x100/0x100 [ 51.080432] ? mark_held_locks+0xb1/0x100 [ 51.084599] ? _raw_spin_unlock_irqrestore+0x6b/0xe0 [ 51.089682] ? _raw_spin_unlock_irqrestore+0x6b/0xe0 [ 51.094766] ? lockdep_hardirqs_on+0x415/0x5d0 [ 51.099340] ? trace_hardirqs_off_caller+0x300/0x300 [ 51.104436] ? do_raw_spin_trylock+0x270/0x270 [ 51.109026] ? add_lock_to_list.isra.0+0x450/0x450 [ 51.113931] ? print_usage_bug+0xd0/0xd0 [ 51.117972] ? _raw_spin_unlock_irqrestore+0xa4/0xe0 [ 51.123053] ? __lock_is_held+0xb6/0x140 [ 51.127124] lock_acquire+0x1db/0x570 [ 51.130916] ? fifo_open+0x159/0xb00 [ 51.134613] ? ___might_sleep+0x1e7/0x310 [ 51.138739] ? lock_release+0xc40/0xc40 [ 51.142693] ? fifo_open+0x159/0xb00 [ 51.146406] ? fifo_open+0x159/0xb00 [ 51.150136] __mutex_lock+0x12f/0x1670 [ 51.154003] ? fifo_open+0x159/0xb00 [ 51.157706] ? __sanitizer_cov_trace_const_cmp4+0x16/0x20 [ 51.163231] ? __sanitizer_cov_trace_const_cmp4+0x16/0x20 [ 51.168746] ? fifo_open+0x159/0xb00 [ 51.172481] ? lockdep_init_map+0x10c/0x5b0 [ 51.176786] ? mutex_trylock+0x2d0/0x2d0 [ 51.180826] ? add_lock_to_list.isra.0+0x450/0x450 [ 51.185738] ? __mutex_init+0x1f6/0x2a0 [ 51.189700] ? psi_task_change.cold+0x1ec/0x1ec [ 51.194346] ? fifo_open+0x2b5/0xb00 [ 51.198036] ? find_held_lock+0x35/0x120 [ 51.202074] ? fifo_open+0x2b5/0xb00 [ 51.205786] ? lock_acquire+0x1db/0x570 [ 51.209744] ? kasan_check_read+0x11/0x20 [ 51.213897] ? do_raw_spin_unlock+0xa0/0x330 [ 51.218295] ? do_raw_spin_trylock+0x270/0x270 [ 51.222891] mutex_lock_nested+0x16/0x20 [ 51.226946] ? _raw_spin_unlock+0x2d/0x50 [ 51.231076] ? mutex_lock_nested+0x16/0x20 [ 51.235305] fifo_open+0x159/0xb00 [ 51.238832] do_dentry_open+0x48a/0x1210 [ 51.242900] ? pipe_release+0x280/0x280 [ 51.246882] ? chown_common+0x740/0x740 [ 51.250848] ? security_inode_permission+0xd5/0x110 [ 51.255859] ? inode_permission+0xb4/0x570 [ 51.260076] vfs_open+0xa0/0xd0 [ 51.263332] path_openat+0x144f/0x5650 [ 51.267198] ? add_lock_to_list.isra.0+0x450/0x450 [ 51.272109] ? __sanitizer_cov_trace_const_cmp4+0x16/0x20 [ 51.277628] ? __sanitizer_cov_trace_const_cmp4+0x16/0x20 [ 51.283156] ? path_lookupat.isra.0+0xba0/0xba0 [ 51.287840] ? psi_task_change.cold+0x1ec/0x1ec [ 51.292523] ? __lock_acquire+0x572/0x4a30 [ 51.296736] ? __x64_sys_execve+0x8f/0xc0 [ 51.300865] ? new_task_smack+0x26a/0x330 [ 51.305007] do_filp_open+0x26f/0x370 [ 51.308802] ? may_open_dev+0x100/0x100 [ 51.312772] ? smack_cred_alloc_blank+0x80/0x80 [ 51.317474] ? add_lock_to_list.isra.0+0x450/0x450 [ 51.322385] ? add_lock_to_list.isra.0+0x450/0x450 [ 51.327296] ? refcount_add_not_zero_checked+0x330/0x330 [ 51.332723] ? prepare_creds+0xa4/0x4e0 [ 51.336683] ? prepare_creds+0xa4/0x4e0 [ 51.340657] ? __do_execve_file.isra.0+0x908/0x2510 [ 51.345656] do_open_execat+0x20e/0x930 [ 51.349620] ? unregister_binfmt+0x2b0/0x2b0 [ 51.354022] ? kasan_check_read+0x11/0x20 [ 51.358153] ? do_raw_spin_trylock+0x270/0x270 [ 51.362714] ? key_put+0x36/0x90 [ 51.366063] __do_execve_file.isra.0+0x181e/0x2510 [ 51.370979] ? prepare_bprm_creds+0x120/0x120 [ 51.375483] ? __sanitizer_cov_trace_const_cmp8+0x18/0x20 [ 51.380999] ? strncpy_from_user+0x317/0x440 [ 51.385402] ? digsig_verify.cold+0x32/0x32 [ 51.389707] ? kmem_cache_alloc+0x341/0x710 [ 51.394008] ? do_syscall_64+0x8c/0x800 [ 51.397966] ? __sanitizer_cov_trace_const_cmp4+0x16/0x20 [ 51.403483] ? getname_flags+0x277/0x5b0 [ 51.407529] ? trace_hardirqs_off_caller+0x300/0x300 [ 51.412609] __x64_sys_execve+0x8f/0xc0 [ 51.416562] do_syscall_64+0x1a3/0x800 [ 51.420475] ? syscall_return_slowpath+0x5f0/0x5f0 [ 51.425403] ? prepare_exit_to_usermode+0x3b0/0x3b0 [ 51.430398] ? __switch_to_asm+0x34/0x70 [ 51.434438] ? trace_hardirqs_off_thunk+0x1a/0x1c [ 51.439287] entry_SYSCALL_64_after_hwframe+0x49/0xbe [ 51.444471] RIP: 0033:0x445729 [ 51.447665] Code: e8 6c b6 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 2b 12 fc ff c3 66 2e 0f 1f 84 00 00 00 00 [ 51.466548] RSP: 002b:00007f69804a6da8 EFLAGS: 00000246 ORIG_RAX: 000000000000003b [ 51.474248] RAX: ffffffffffffffda RBX: 00000000006dac58 RCX: 0000000000445729 [ 51.481503] RDX: 0000000000000000 RSI: 0000000000000000 RDI: 0000000020000340 [ 51.488756] RBP: 00000000006dac50 R08: 0000000000000000 R09: 0000000000000000 [ 51.496003] R10: 0000000000000000 R11: 0000000000000246 R12: 00000000006dac5c [ 51.503272] R13: 0030656