[ 37.389911][ T26] audit: type=1800 audit(1553304791.225:27): pid=7612 uid=0 auid=4294967295 ses=4294967295 subj==unconfined op=collect_data cause=failed(directio) comm="startpar" name="restorecond" dev="sda1" ino=2436 res=0 [ 37.411573][ T26] audit: type=1800 audit(1553304791.225:28): pid=7612 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. [ 38.247351][ T26] audit: type=1800 audit(1553304792.165:29): pid=7612 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 [ 38.267512][ T26] audit: type=1800 audit(1553304792.165:30): pid=7612 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 Warning: Permanently added '10.128.0.15' (ECDSA) to the list of known hosts. executing program syzkaller login: [ 49.256417][ T7765] [ 49.259110][ T7765] ====================================================== [ 49.266300][ T7765] WARNING: possible circular locking dependency detected [ 49.273629][ T7765] 5.1.0-rc1+ #33 Not tainted [ 49.278473][ T7765] ------------------------------------------------------ [ 49.285953][ T7765] syz-executor850/7765 is trying to acquire lock: [ 49.292477][ T7765] 00000000d6dfb9eb (&pipe->mutex/1){+.+.}, at: fifo_open+0x159/0xb00 [ 49.300974][ T7765] [ 49.300974][ T7765] but task is already holding lock: [ 49.308783][ T7765] 00000000f27e5005 (&sig->cred_guard_mutex){+.+.}, at: __do_execve_file.isra.0+0x376/0x23f0 [ 49.319383][ T7765] [ 49.319383][ T7765] which lock already depends on the new lock. [ 49.319383][ T7765] [ 49.329987][ T7765] [ 49.329987][ T7765] the existing dependency chain (in reverse order) is: [ 49.339174][ T7765] [ 49.339174][ T7765] -> #1 (&sig->cred_guard_mutex){+.+.}: [ 49.347368][ T7765] lock_acquire+0x16f/0x3f0 [ 49.352570][ T7765] __mutex_lock+0xf7/0x1310 [ 49.357650][ T7765] mutex_lock_interruptible_nested+0x16/0x20 [ 49.364858][ T7765] proc_pid_attr_write+0x200/0x580 [ 49.370485][ T7765] __vfs_write+0x8d/0x110 [ 49.375554][ T7765] __kernel_write+0x110/0x3b0 [ 49.381016][ T7765] write_pipe_buf+0x15d/0x1f0 [ 49.386302][ T7765] __splice_from_pipe+0x395/0x7d0 [ 49.392286][ T7765] splice_from_pipe+0x108/0x170 [ 49.397723][ T7765] default_file_splice_write+0x3c/0x90 [ 49.403848][ T7765] do_splice+0x70a/0x13c0 [ 49.408722][ T7765] __x64_sys_splice+0x2c6/0x330 [ 49.414183][ T7765] do_syscall_64+0x103/0x610 [ 49.419473][ T7765] entry_SYSCALL_64_after_hwframe+0x49/0xbe [ 49.425870][ T7765] [ 49.425870][ T7765] -> #0 (&pipe->mutex/1){+.+.}: [ 49.432896][ T7765] __lock_acquire+0x239c/0x3fb0 [ 49.438263][ T7765] lock_acquire+0x16f/0x3f0 [ 49.443280][ T7765] __mutex_lock+0xf7/0x1310 [ 49.448306][ T7765] mutex_lock_nested+0x16/0x20 [ 49.453586][ T7765] fifo_open+0x159/0xb00 [ 49.458498][ T7765] do_dentry_open+0x488/0x1160 [ 49.463784][ T7765] vfs_open+0xa0/0xd0 [ 49.468556][ T7765] path_openat+0x10e9/0x46e0 [ 49.473691][ T7765] do_filp_open+0x1a1/0x280 [ 49.479009][ T7765] do_open_execat+0x137/0x690 [ 49.484472][ T7765] __do_execve_file.isra.0+0x178d/0x23f0 [ 49.490769][ T7765] __x64_sys_execve+0x8f/0xc0 [ 49.496093][ T7765] do_syscall_64+0x103/0x610 [ 49.501342][ T7765] entry_SYSCALL_64_after_hwframe+0x49/0xbe [ 49.508000][ T7765] [ 49.508000][ T7765] other info that might help us debug this: [ 49.508000][ T7765] [ 49.518427][ T7765] Possible unsafe locking scenario: [ 49.518427][ T7765] [ 49.525959][ T7765] CPU0 CPU1 [ 49.531449][ T7765] ---- ---- [ 49.536921][ T7765] lock(&sig->cred_guard_mutex); [ 49.541965][ T7765] lock(&pipe->mutex/1); [ 49.548860][ T7765] lock(&sig->cred_guard_mutex); [ 49.556391][ T7765] lock(&pipe->mutex/1); [ 49.560854][ T7765] [ 49.560854][ T7765] *** DEADLOCK *** [ 49.560854][ T7765] [ 49.569078][ T7765] 1 lock held by syz-executor850/7765: [ 49.574525][ T7765] #0: 00000000f27e5005 (&sig->cred_guard_mutex){+.+.}, at: __do_execve_file.isra.0+0x376/0x23f0 [ 49.585377][ T7765] [ 49.585377][ T7765] stack backtrace: [ 49.591568][ T7765] CPU: 1 PID: 7765 Comm: syz-executor850 Not tainted 5.1.0-rc1+ #33 [ 49.599942][ T7765] Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 [ 49.610121][ T7765] Call Trace: [ 49.613454][ T7765] dump_stack+0x172/0x1f0 [ 49.618003][ T7765] print_circular_bug.isra.0.cold+0x1cc/0x28f [ 49.624067][ T7765] check_prev_add.constprop.0+0xf11/0x23c0 [ 49.630000][ T7765] ? depot_save_stack+0x1de/0x460 [ 49.635168][ T7765] ? check_usage+0x570/0x570 [ 49.639752][ T7765] ? mark_held_locks+0xa4/0xf0 [ 49.644597][ T7765] ? _raw_spin_unlock_irqrestore+0x6b/0xe0 [ 49.650608][ T7765] ? graph_lock+0x7b/0x200 [ 49.655109][ T7765] ? __lockdep_reset_lock+0x450/0x450 [ 49.660821][ T7765] ? __sanitizer_cov_trace_const_cmp8+0x18/0x20 [ 49.667056][ T7765] __lock_acquire+0x239c/0x3fb0 [ 49.671901][ T7765] ? save_stack+0xa9/0xd0 [ 49.676375][ T7765] ? mark_held_locks+0xf0/0xf0 [ 49.681134][ T7765] lock_acquire+0x16f/0x3f0 [ 49.685730][ T7765] ? fifo_open+0x159/0xb00 [ 49.690369][ T7765] ? fifo_open+0x159/0xb00 [ 49.694860][ T7765] __mutex_lock+0xf7/0x1310 [ 49.699808][ T7765] ? fifo_open+0x159/0xb00 [ 49.704305][ T7765] ? fifo_open+0x159/0xb00 [ 49.708880][ T7765] ? fifo_open+0x2b5/0xb00 [ 49.713295][ T7765] ? mutex_trylock+0x1e0/0x1e0 [ 49.718262][ T7765] ? fifo_open+0x2b5/0xb00 [ 49.723048][ T7765] ? kasan_check_write+0x14/0x20 [ 49.728044][ T7765] ? lock_downgrade+0x880/0x880 [ 49.732894][ T7765] mutex_lock_nested+0x16/0x20 [ 49.737655][ T7765] ? mutex_lock_nested+0x16/0x20 [ 49.742816][ T7765] fifo_open+0x159/0xb00 [ 49.747226][ T7765] do_dentry_open+0x488/0x1160 [ 49.752111][ T7765] ? pipe_release+0x280/0x280 [ 49.756998][ T7765] ? chown_common+0x5c0/0x5c0 [ 49.761695][ T7765] ? inode_permission+0xb4/0x570 [ 49.766762][ T7765] vfs_open+0xa0/0xd0 [ 49.771295][ T7765] path_openat+0x10e9/0x46e0 [ 49.775880][ T7765] ? path_lookupat.isra.0+0x8d0/0x8d0 [ 49.781994][ T7765] ? __kmalloc+0x15c/0x740 [ 49.786409][ T7765] ? prepare_creds+0x2f5/0x3f0 [ 49.791252][ T7765] ? prepare_exec_creds+0x12/0xf0 [ 49.796269][ T7765] ? __do_execve_file.isra.0+0x393/0x23f0 [ 49.802061][ T7765] ? do_syscall_64+0x103/0x610 [ 49.806821][ T7765] ? entry_SYSCALL_64_after_hwframe+0x49/0xbe [ 49.813014][ T7765] ? __lock_acquire+0x548/0x3fb0 [ 49.818185][ T7765] ? prepare_exec_creds+0x12/0xf0 [ 49.823322][ T7765] ? __do_execve_file.isra.0+0x393/0x23f0 [ 49.829235][ T7765] ? __x64_sys_execve+0x8f/0xc0 [ 49.834083][ T7765] do_filp_open+0x1a1/0x280 [ 49.838653][ T7765] ? may_open_dev+0x100/0x100 [ 49.843438][ T7765] ? __lock_acquire+0x548/0x3fb0 [ 49.848696][ T7765] do_open_execat+0x137/0x690 [ 49.853372][ T7765] ? unregister_binfmt+0x170/0x170 [ 49.858482][ T7765] ? lock_downgrade+0x880/0x880 [ 49.863329][ T7765] ? __sanitizer_cov_trace_const_cmp4+0x16/0x20 [ 49.869767][ T7765] ? kasan_check_read+0x11/0x20 [ 49.874791][ T7765] ? do_raw_spin_unlock+0x57/0x270 [ 49.879900][ T7765] __do_execve_file.isra.0+0x178d/0x23f0 [ 49.885612][ T7765] ? __sanitizer_cov_trace_cmp8+0x18/0x20 [ 49.891352][ T7765] ? __check_object_size+0x3d/0x42f [ 49.896620][ T7765] ? copy_strings_kernel+0x110/0x110 [ 49.902206][ T7765] ? __sanitizer_cov_trace_const_cmp4+0x16/0x20 [ 49.908439][ T7765] ? getname_flags+0x277/0x5b0 [ 49.913203][ T7765] ? entry_SYSCALL_64_after_hwframe+0x49/0xbe [ 49.919350][ T7765] __x64_sys_execve+0x8f/0xc0 [ 49.924022][ T7765] do_syscall_64+0x103/0x610 [ 49.928608][ T7765] entry_SYSCALL_64_after_hwframe+0x49/0xbe [ 49.934624][ T7765] RIP: 0033:0x4402a9 [ 49.938599][ T7765] 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 [ 49.958817][ T7765] RSP: 002b:00007fff212954a8 EFLAGS: 00000246 ORIG_RAX: 000000000000003b [ 49.967218][ T7765] RAX: ffffffffffffffda RBX: 00000000004002c8 RCX: 00000000004402a9 [ 49.975274][ T7765] RDX: 0000000000000000 RSI: 0000000000000000 RDI: 0000000020000480 [ 49.983238][ T7765] RBP: 00000000006ca018 R08: 0000000000000000 R09: 0000000000000000 [ 49.991472][ T7765] R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000401b30 [ 49.999519][ T7765] R13: 0000000000401bc0 R14: 0000000000000000 R15: 0000000000000000