[ 35.098389][ T26] audit: type=1800 audit(1546907767.338:27): pid=7481 uid=0 auid=4294967295 ses=4294967295 subj==unconfined op=collect_data cause=failed(directio) comm="startpar" name="restorecond" dev="sda1" ino=2436 res=0 [ 35.120486][ T26] audit: type=1800 audit(1546907767.338:28): pid=7481 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. [ 35.621807][ T26] audit: type=1800 audit(1546907767.928:29): pid=7481 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 [ 35.646207][ T26] audit: type=1800 audit(1546907767.928:30): pid=7481 uid=0 auid=4294967295 ses=4294967295 subj==unconfined op=collect_data cause=failed(directio) comm="startpar" name="rmnologin" dev="sda1" ino=2423 res=0 Debian GNU/Linux 7 syzkaller ttyS0 syzkaller login: [ 36.976595][ T7617] sshd (7617) used greatest stack depth: 19848 bytes left Warning: Permanently added '10.128.0.38' (ECDSA) to the list of known hosts. executing program [ 43.611603][ T7635] [ 43.613938][ T7635] ====================================================== [ 43.620927][ T7635] WARNING: possible circular locking dependency detected [ 43.627934][ T7635] 4.20.0-next-20190107 #6 Not tainted [ 43.633283][ T7635] ------------------------------------------------------ [ 43.640395][ T7635] syz-executor551/7635 is trying to acquire lock: [ 43.646775][ T7635] 0000000018e7c906 (&pipe->mutex/1){+.+.}, at: fifo_open+0x159/0xb00 [ 43.654821][ T7635] [ 43.654821][ T7635] but task is already holding lock: [ 43.662154][ T7635] 0000000083307f8b (&sig->cred_guard_mutex){+.+.}, at: __do_execve_file.isra.0+0x45d/0x2700 [ 43.672191][ T7635] [ 43.672191][ T7635] which lock already depends on the new lock. [ 43.672191][ T7635] [ 43.682565][ T7635] [ 43.682565][ T7635] the existing dependency chain (in reverse order) is: [ 43.691550][ T7635] [ 43.691550][ T7635] -> #1 (&sig->cred_guard_mutex){+.+.}: [ 43.699244][ T7635] __mutex_lock+0x12f/0x1670 [ 43.704326][ T7635] mutex_lock_interruptible_nested+0x16/0x20 [ 43.710799][ T7635] proc_pid_attr_write+0x1fa/0x530 [ 43.716402][ T7635] __vfs_write+0x116/0xb40 [ 43.721314][ T7635] __kernel_write+0x110/0x3b0 [ 43.726584][ T7635] write_pipe_buf+0x180/0x240 [ 43.731755][ T7635] __splice_from_pipe+0x39a/0x7e0 [ 43.737288][ T7635] splice_from_pipe+0x1ea/0x310 [ 43.742628][ T7635] default_file_splice_write+0x3c/0x90 [ 43.748579][ T7635] do_splice+0x64b/0x1410 [ 43.753401][ T7635] __x64_sys_splice+0x2c6/0x330 [ 43.758745][ T7635] do_syscall_64+0x1a3/0x800 [ 43.763829][ T7635] entry_SYSCALL_64_after_hwframe+0x49/0xbe [ 43.770208][ T7635] [ 43.770208][ T7635] -> #0 (&pipe->mutex/1){+.+.}: [ 43.777216][ T7635] lock_acquire+0x1db/0x570 [ 43.782210][ T7635] __mutex_lock+0x12f/0x1670 [ 43.787295][ T7635] mutex_lock_nested+0x16/0x20 [ 43.792550][ T7635] fifo_open+0x159/0xb00 [ 43.797283][ T7635] do_dentry_open+0x495/0x1230 [ 43.802543][ T7635] vfs_open+0xa0/0xd0 [ 43.807022][ T7635] path_openat+0x144f/0x5660 [ 43.812102][ T7635] do_filp_open+0x26f/0x370 [ 43.817097][ T7635] do_open_execat+0x207/0x8e0 [ 43.822268][ T7635] __do_execve_file.isra.0+0x1966/0x2700 [ 43.828414][ T7635] __x64_sys_execve+0x8f/0xc0 [ 43.833592][ T7635] do_syscall_64+0x1a3/0x800 [ 43.838691][ T7635] entry_SYSCALL_64_after_hwframe+0x49/0xbe [ 43.845066][ T7635] [ 43.845066][ T7635] other info that might help us debug this: [ 43.845066][ T7635] [ 43.855375][ T7635] Possible unsafe locking scenario: [ 43.855375][ T7635] [ 43.863109][ T7635] CPU0 CPU1 [ 43.868454][ T7635] ---- ---- [ 43.873795][ T7635] lock(&sig->cred_guard_mutex); [ 43.878786][ T7635] lock(&pipe->mutex/1); [ 43.885600][ T7635] lock(&sig->cred_guard_mutex); [ 43.893103][ T7635] lock(&pipe->mutex/1); [ 43.897399][ T7635] [ 43.897399][ T7635] *** DEADLOCK *** [ 43.897399][ T7635] [ 43.905516][ T7635] 1 lock held by syz-executor551/7635: [ 43.910948][ T7635] #0: 0000000083307f8b (&sig->cred_guard_mutex){+.+.}, at: __do_execve_file.isra.0+0x45d/0x2700 [ 43.921420][ T7635] [ 43.921420][ T7635] stack backtrace: [ 43.927280][ T7635] CPU: 0 PID: 7635 Comm: syz-executor551 Not tainted 4.20.0-next-20190107 #6 [ 43.936024][ T7635] Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 [ 43.946045][ T7635] Call Trace: [ 43.949310][ T7635] dump_stack+0x1db/0x2d0 [ 43.953610][ T7635] ? dump_stack_print_info.cold+0x20/0x20 [ 43.959301][ T7635] ? print_stack_trace+0x77/0xb0 [ 43.964230][ T7635] ? vprintk_func+0x86/0x189 [ 43.968793][ T7635] print_circular_bug.isra.0.cold+0x1cc/0x28f [ 43.974831][ T7635] __lock_acquire+0x2fed/0x4a10 [ 43.979653][ T7635] ? is_bpf_text_address+0xac/0x170 [ 43.984826][ T7635] ? mark_held_locks+0x100/0x100 [ 43.989746][ T7635] ? mark_held_locks+0xb1/0x100 [ 43.994572][ T7635] ? _raw_spin_unlock_irqrestore+0x6b/0xe0 [ 44.000347][ T7635] ? lockdep_hardirqs_on+0x415/0x5d0 [ 44.005601][ T7635] ? depot_save_stack+0x1de/0x460 [ 44.010599][ T7635] ? trace_hardirqs_off_caller+0x300/0x300 [ 44.016373][ T7635] ? do_raw_spin_trylock+0x270/0x270 [ 44.021629][ T7635] ? add_lock_to_list.isra.0+0x450/0x450 [ 44.027236][ T7635] ? print_usage_bug+0xd0/0xd0 [ 44.031972][ T7635] ? __lock_is_held+0xb6/0x140 [ 44.036715][ T7635] lock_acquire+0x1db/0x570 [ 44.041190][ T7635] ? fifo_open+0x159/0xb00 [ 44.045578][ T7635] ? ___might_sleep+0x1e7/0x310 [ 44.050396][ T7635] ? lock_release+0xc40/0xc40 [ 44.055061][ T7635] ? fifo_open+0x159/0xb00 [ 44.059463][ T7635] ? fifo_open+0x159/0xb00 [ 44.063858][ T7635] __mutex_lock+0x12f/0x1670 [ 44.068436][ T7635] ? fifo_open+0x159/0xb00 [ 44.072837][ T7635] ? __sanitizer_cov_trace_const_cmp4+0x16/0x20 [ 44.079049][ T7635] ? __sanitizer_cov_trace_const_cmp4+0x16/0x20 [ 44.085258][ T7635] ? fifo_open+0x159/0xb00 [ 44.089645][ T7635] ? lockdep_init_map+0x10c/0x5b0 [ 44.094645][ T7635] ? mutex_trylock+0x2d0/0x2d0 [ 44.099382][ T7635] ? add_lock_to_list.isra.0+0x450/0x450 [ 44.104987][ T7635] ? __mutex_init+0x1f6/0x2a0 [ 44.109637][ T7635] ? psi_task_change.cold+0x1ec/0x1ec [ 44.114981][ T7635] ? fifo_open+0x2b5/0xb00 [ 44.119370][ T7635] ? find_held_lock+0x35/0x120 [ 44.124105][ T7635] ? fifo_open+0x2b5/0xb00 [ 44.128494][ T7635] ? lock_acquire+0x1db/0x570 [ 44.133144][ T7635] ? kasan_check_read+0x11/0x20 [ 44.137974][ T7635] ? do_raw_spin_unlock+0xa0/0x330 [ 44.143053][ T7635] ? do_raw_spin_trylock+0x270/0x270 [ 44.148325][ T7635] mutex_lock_nested+0x16/0x20 [ 44.153061][ T7635] ? mutex_lock_nested+0x16/0x20 [ 44.157970][ T7635] fifo_open+0x159/0xb00 [ 44.162184][ T7635] do_dentry_open+0x495/0x1230 [ 44.166920][ T7635] ? do_raw_spin_unlock+0xa0/0x330 [ 44.172006][ T7635] ? pipe_release+0x280/0x280 [ 44.176660][ T7635] ? chown_common+0x740/0x740 [ 44.181314][ T7635] ? security_inode_permission+0xd5/0x110 [ 44.187009][ T7635] ? inode_permission+0xb4/0x570 [ 44.191917][ T7635] vfs_open+0xa0/0xd0 [ 44.195871][ T7635] path_openat+0x144f/0x5660 [ 44.200433][ T7635] ? is_bpf_text_address+0xd3/0x170 [ 44.205612][ T7635] ? path_lookupat.isra.0+0xba0/0xba0 [ 44.210960][ T7635] ? __lock_acquire+0x572/0x4a10 [ 44.215877][ T7635] ? kmem_cache_alloc+0x12d/0x710 [ 44.220873][ T7635] ? __do_execve_file.isra.0+0x47a/0x2700 [ 44.226582][ T7635] ? __x64_sys_execve+0x8f/0xc0 [ 44.231407][ T7635] ? do_syscall_64+0x1a3/0x800 [ 44.236143][ T7635] ? entry_SYSCALL_64_after_hwframe+0x49/0xbe [ 44.242174][ T7635] ? add_lock_to_list.isra.0+0x450/0x450 [ 44.247779][ T7635] do_filp_open+0x26f/0x370 [ 44.252254][ T7635] ? may_open_dev+0x100/0x100 [ 44.256900][ T7635] ? refcount_dec_and_mutex_lock+0x90/0x90 [ 44.262678][ T7635] ? prepare_creds+0xa4/0x4e0 [ 44.267330][ T7635] ? add_lock_to_list.isra.0+0x450/0x450 [ 44.272932][ T7635] ? add_lock_to_list.isra.0+0x450/0x450 [ 44.278553][ T7635] ? __do_execve_file.isra.0+0x901/0x2700 [ 44.284254][ T7635] do_open_execat+0x207/0x8e0 [ 44.288904][ T7635] ? unregister_binfmt+0x2b0/0x2b0 [ 44.293988][ T7635] ? kasan_check_read+0x11/0x20 [ 44.298811][ T7635] ? do_raw_spin_trylock+0x270/0x270 [ 44.304065][ T7635] ? __phys_addr_symbol+0x30/0x70 [ 44.309063][ T7635] __do_execve_file.isra.0+0x1966/0x2700 [ 44.314676][ T7635] ? copy_strings_kernel+0x110/0x110 [ 44.319946][ T7635] ? __sanitizer_cov_trace_const_cmp8+0x18/0x20 [ 44.326158][ T7635] ? strncpy_from_user+0x3aa/0x4e0 [ 44.331241][ T7635] ? digsig_verify.cold+0x32/0x32 [ 44.336236][ T7635] ? kmem_cache_alloc+0x341/0x710 [ 44.341241][ T7635] ? do_syscall_64+0x8c/0x800 [ 44.345994][ T7635] ? __sanitizer_cov_trace_const_cmp4+0x16/0x20 [ 44.352208][ T7635] ? getname_flags+0x277/0x5b0 [ 44.356946][ T7635] ? trace_hardirqs_off_caller+0x300/0x300 [ 44.362724][ T7635] __x64_sys_execve+0x8f/0xc0 [ 44.367374][ T7635] do_syscall_64+0x1a3/0x800 [ 44.371935][ T7635] ? syscall_return_slowpath+0x5f0/0x5f0 [ 44.377537][ T7635] ? prepare_exit_to_usermode+0x3b0/0x3b0 [ 44.383230][ T7635] ? __switch_to_asm+0x34/0x70 [ 44.387966][ T7635] ? trace_hardirqs_off_thunk+0x1a/0x1c [ 44.393497][ T7635] entry_SYSCALL_64_after_hwframe+0x49/0xbe [ 44.399370][ T7635] RIP: 0033:0x445709 [ 44.403248][ T7635] 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 [ 44.422934][ T7635] RSP: 002b:00007f0573f90d18 EFLAGS: 00000246 ORIG_RAX: 000000000000003b [ 44.431316][ T7635] RAX: ffffffffffffffda RBX: 00000000006dac58 RCX: 0000000000445709 [ 44.439376][ T7635] RDX: 0000000000000000 RSI: 0000000000000000 RDI: 0000000020000380 [ 44.447324][ T7635] RBP: 00000000006dac50 R08: 68742f636f72702f R09: 68742f636f72702f [ 44.455264][ T7635] R10: 0000000000000000 R11: 0000000000000246 R12: 00000000006dac5c [ 44.463207][ T7635] R1