Starting mcstransd: [....] Starting periodic command scheduler: cron[?25l[?1c7[ ok 8[?25h[?0c. [....] Starting file context maintaining daemon: restorecond[?25l[?1c7[ ok 8[?25h[?0c. [....] Starting OpenBSD Secure Shell server: sshd[?25l[?1c7[ ok 8[?25h[?0c. [....] startpar: service(s) returned failure: ssh ...[?25l[?1c7[FAIL8[?25h[?0c failed! Debian GNU/Linux 7 syzkaller ttyS0 syzkaller login: [ 45.927199][ T26] kauditd_printk_skb: 2 callbacks suppressed [ 45.927215][ T26] audit: type=1400 audit(1552755365.193:35): avc: denied { map } for pid=8109 comm="bash" path="/bin/bash" dev="sda1" ino=1457 scontext=unconfined_u:system_r:insmod_t:s0-s0:c0.c1023 tcontext=system_u:object_r:file_t:s0 tclass=file permissive=1 Warning: Permanently added '10.128.0.40' (ECDSA) to the list of known hosts. executing program [ 59.009528][ T26] audit: type=1400 audit(1552755378.273:36): avc: denied { map } for pid=8121 comm="syz-executor771" path="/root/syz-executor771722015" dev="sda1" ino=16484 scontext=unconfined_u:system_r:insmod_t:s0-s0:c0.c1023 tcontext=unconfined_u:object_r:user_home_t:s0 tclass=file permissive=1 [ 59.015965][ T8121] [ 59.050884][ T8121] ====================================================== [ 59.058111][ T8121] WARNING: possible circular locking dependency detected [ 59.065169][ T8121] 5.0.0+ #25 Not tainted [ 59.069824][ T8121] ------------------------------------------------------ [ 59.077347][ T8121] syz-executor771/8121 is trying to acquire lock: [ 59.084661][ T8121] 0000000098457acc (&pipe->mutex/1){+.+.}, at: fifo_open+0x159/0xb00 [ 59.093035][ T8121] [ 59.093035][ T8121] but task is already holding lock: [ 59.100492][ T8121] 000000003774d706 (&sig->cred_guard_mutex){+.+.}, at: __do_execve_file.isra.0+0x376/0x23f0 [ 59.110684][ T8121] [ 59.110684][ T8121] which lock already depends on the new lock. [ 59.110684][ T8121] [ 59.121132][ T8121] [ 59.121132][ T8121] the existing dependency chain (in reverse order) is: [ 59.130408][ T8121] [ 59.130408][ T8121] -> #1 (&sig->cred_guard_mutex){+.+.}: [ 59.138449][ T8121] lock_acquire+0x16f/0x3f0 [ 59.143548][ T8121] __mutex_lock+0xf7/0x1310 [ 59.148606][ T8121] mutex_lock_interruptible_nested+0x16/0x20 [ 59.155430][ T8121] proc_pid_attr_write+0x200/0x580 [ 59.161049][ T8121] __vfs_write+0x8d/0x110 [ 59.166029][ T8121] __kernel_write+0x110/0x3b0 [ 59.171303][ T8121] write_pipe_buf+0x15d/0x1f0 [ 59.176649][ T8121] __splice_from_pipe+0x395/0x7d0 [ 59.182203][ T8121] splice_from_pipe+0x108/0x170 [ 59.188028][ T8121] default_file_splice_write+0x3c/0x90 [ 59.194232][ T8121] do_splice+0x70a/0x13c0 [ 59.199252][ T8121] __x64_sys_splice+0x2c6/0x330 [ 59.204965][ T8121] do_syscall_64+0x103/0x610 [ 59.210297][ T8121] entry_SYSCALL_64_after_hwframe+0x49/0xbe [ 59.216703][ T8121] [ 59.216703][ T8121] -> #0 (&pipe->mutex/1){+.+.}: [ 59.223835][ T8121] __lock_acquire+0x239c/0x3fb0 [ 59.229357][ T8121] lock_acquire+0x16f/0x3f0 [ 59.234374][ T8121] __mutex_lock+0xf7/0x1310 [ 59.239511][ T8121] mutex_lock_nested+0x16/0x20 [ 59.244788][ T8121] fifo_open+0x159/0xb00 [ 59.249538][ T8121] do_dentry_open+0x488/0x1160 [ 59.254839][ T8121] vfs_open+0xa0/0xd0 [ 59.259435][ T8121] path_openat+0x10e9/0x46e0 [ 59.264722][ T8121] do_filp_open+0x1a1/0x280 [ 59.270904][ T8121] do_open_execat+0x137/0x690 [ 59.276172][ T8121] __do_execve_file.isra.0+0x178d/0x23f0 [ 59.282816][ T8121] __x64_sys_execve+0x8f/0xc0 [ 59.288058][ T8121] do_syscall_64+0x103/0x610 [ 59.293343][ T8121] entry_SYSCALL_64_after_hwframe+0x49/0xbe [ 59.299961][ T8121] [ 59.299961][ T8121] other info that might help us debug this: [ 59.299961][ T8121] [ 59.310180][ T8121] Possible unsafe locking scenario: [ 59.310180][ T8121] [ 59.317813][ T8121] CPU0 CPU1 [ 59.323254][ T8121] ---- ---- [ 59.328605][ T8121] lock(&sig->cred_guard_mutex); [ 59.333665][ T8121] lock(&pipe->mutex/1); [ 59.340721][ T8121] lock(&sig->cred_guard_mutex); [ 59.348669][ T8121] lock(&pipe->mutex/1); [ 59.352996][ T8121] [ 59.352996][ T8121] *** DEADLOCK *** [ 59.352996][ T8121] [ 59.361337][ T8121] 1 lock held by syz-executor771/8121: [ 59.366918][ T8121] #0: 000000003774d706 (&sig->cred_guard_mutex){+.+.}, at: __do_execve_file.isra.0+0x376/0x23f0 [ 59.377409][ T8121] [ 59.377409][ T8121] stack backtrace: [ 59.383399][ T8121] CPU: 0 PID: 8121 Comm: syz-executor771 Not tainted 5.0.0+ #25 [ 59.391066][ T8121] Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 [ 59.401209][ T8121] Call Trace: [ 59.404557][ T8121] dump_stack+0x172/0x1f0 [ 59.408881][ T8121] print_circular_bug.isra.0.cold+0x1cc/0x28f [ 59.415228][ T8121] check_prev_add.constprop.0+0xf11/0x23c0 [ 59.421174][ T8121] ? depot_save_stack+0x1de/0x460 [ 59.426391][ T8121] ? check_usage+0x570/0x570 [ 59.430986][ T8121] ? mark_held_locks+0xa4/0xf0 [ 59.435941][ T8121] ? _raw_spin_unlock_irqrestore+0x6b/0xe0 [ 59.441897][ T8121] ? graph_lock+0x7b/0x200 [ 59.446349][ T8121] ? __lockdep_reset_lock+0x450/0x450 [ 59.451887][ T8121] ? __sanitizer_cov_trace_const_cmp8+0x18/0x20 [ 59.458389][ T8121] __lock_acquire+0x239c/0x3fb0 [ 59.463530][ T8121] ? save_stack+0xa9/0xd0 [ 59.468293][ T8121] ? mark_held_locks+0xf0/0xf0 [ 59.473130][ T8121] lock_acquire+0x16f/0x3f0 [ 59.478017][ T8121] ? fifo_open+0x159/0xb00 [ 59.482647][ T8121] ? fifo_open+0x159/0xb00 [ 59.487173][ T8121] __mutex_lock+0xf7/0x1310 [ 59.491796][ T8121] ? fifo_open+0x159/0xb00 [ 59.496242][ T8121] ? fifo_open+0x159/0xb00 [ 59.500999][ T8121] ? fifo_open+0x2b5/0xb00 [ 59.505404][ T8121] ? mutex_trylock+0x1e0/0x1e0 [ 59.510274][ T8121] ? fifo_open+0x2b5/0xb00 [ 59.514696][ T8121] ? kasan_check_write+0x14/0x20 [ 59.519664][ T8121] ? lock_downgrade+0x880/0x880 [ 59.524625][ T8121] mutex_lock_nested+0x16/0x20 [ 59.529374][ T8121] ? mutex_lock_nested+0x16/0x20 [ 59.534394][ T8121] fifo_open+0x159/0xb00 [ 59.538735][ T8121] do_dentry_open+0x488/0x1160 [ 59.543498][ T8121] ? pipe_release+0x280/0x280 [ 59.548160][ T8121] ? chown_common+0x5c0/0x5c0 [ 59.552856][ T8121] ? inode_permission+0xb4/0x570 [ 59.557826][ T8121] vfs_open+0xa0/0xd0 [ 59.561867][ T8121] path_openat+0x10e9/0x46e0 [ 59.566450][ T8121] ? path_lookupat.isra.0+0x8d0/0x8d0 [ 59.571944][ T8121] ? __kmalloc+0x15c/0x740 [ 59.576347][ T8121] ? prepare_creds+0x2f5/0x3f0 [ 59.581472][ T8121] ? prepare_exec_creds+0x12/0xf0 [ 59.586482][ T8121] ? __do_execve_file.isra.0+0x393/0x23f0 [ 59.592194][ T8121] ? do_syscall_64+0x103/0x610 [ 59.596939][ T8121] ? entry_SYSCALL_64_after_hwframe+0x49/0xbe [ 59.603131][ T8121] ? __lock_acquire+0x548/0x3fb0 [ 59.608056][ T8121] ? prepare_exec_creds+0x12/0xf0 [ 59.613102][ T8121] ? __do_execve_file.isra.0+0x393/0x23f0 [ 59.619020][ T8121] ? __x64_sys_execve+0x8f/0xc0 [ 59.623854][ T8121] do_filp_open+0x1a1/0x280 [ 59.628348][ T8121] ? may_open_dev+0x100/0x100 [ 59.633010][ T8121] ? __lock_acquire+0x548/0x3fb0 [ 59.637950][ T8121] do_open_execat+0x137/0x690 [ 59.642826][ T8121] ? unregister_binfmt+0x170/0x170 [ 59.647922][ T8121] ? lock_downgrade+0x880/0x880 [ 59.652764][ T8121] ? __sanitizer_cov_trace_const_cmp4+0x16/0x20 [ 59.659068][ T8121] ? kasan_check_read+0x11/0x20 [ 59.663912][ T8121] ? do_raw_spin_unlock+0x57/0x270 [ 59.669020][ T8121] __do_execve_file.isra.0+0x178d/0x23f0 [ 59.674695][ T8121] ? __sanitizer_cov_trace_cmp8+0x18/0x20 [ 59.680578][ T8121] ? __check_object_size+0x3d/0x42f [ 59.685849][ T8121] ? copy_strings_kernel+0x110/0x110 [ 59.691126][ T8121] ? __sanitizer_cov_trace_const_cmp4+0x16/0x20 [ 59.697450][ T8121] ? getname_flags+0x277/0x5b0 [ 59.702233][ T8121] ? entry_SYSCALL_64_after_hwframe+0x49/0xbe [ 59.709502][ T8121] __x64_sys_execve+0x8f/0xc0 [ 59.714242][ T8121] do_syscall_64+0x103/0x610 [ 59.719136][ T8121] entry_SYSCALL_64_after_hwframe+0x49/0xbe [ 59.725199][ T8121] RIP: 0033:0x440289 [ 59.729077][ T8121] 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 [ 59.748862][ T8121] RSP: 002b:00007ffd5a80e678 EFLAGS: 00000246 ORIG_RAX: 000000000000003b [ 59.757349][ T8121] RAX: ffffffffffffffda RBX: 00000000004002c8 RCX: 0000000000440289 [ 59.765315][ T8121] RDX: 0000000000000000 RSI: 0000000000000000 RDI: 0000000020000180 [ 59.773314][ T8121] RBP: 00000000006ca018 R08: 0000000000000000 R09: 0000000000000000 [ 59.781534][ T8121] R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000401b10 [ 59.789613][ T8121] R13: 0000000000401ba0 R14: 0000000000000000 R15: 0000000000000000