[....] Starting enhanced syslogd: rsyslogd[ 9.872349] audit: type=1400 audit(1514127249.147:4): avc: denied { syslog } for pid=3173 comm="rsyslogd" capability=34 scontext=system_u:system_r:kernel_t:s0 tcontext=system_u:system_r:kernel_t:s0 tclass=capability2 permissive=1 [?25l[?1c7[ ok 8[?25h[?0c. [....] Starting periodic command scheduler: cron[?25l[?1c7[ ok 8[?25h[?0c. Starting mcstransd: [....] Starting OpenBSD Secure Shell server: sshd[?25l[?1c7[ ok 8[?25h[?0c. [....] Starting file context maintaining daemon: restorecond[?25l[?1c7[ ok 8[?25h[?0c. Debian GNU/Linux 7 syzkaller ttyS0 Warning: Permanently added 'ci-android-49-kasan-gce-386-4,10.128.15.233' (ECDSA) to the list of known hosts. executing program executing program syzkaller login: [ 31.153049] [ 31.153355] ====================================================== [ 31.154199] [ INFO: possible circular locking dependency detected ] [ 31.155076] 4.9.71-g2506378 #9 Not tainted [ 31.155653] ------------------------------------------------------- [ 31.156549] syzkaller689322/3350 is trying to acquire lock: [ 31.157299] (&p->lock){+.+.+.}, at: [] seq_read+0xdd/0x1290 [ 31.158389] but task is already holding lock: [ 31.159028] (&pipe->mutex/1){+.+.+.}, at: [] pipe_lock+0x56/0x70 [ 31.160204] which lock already depends on the new lock. [ 31.160204] [ 31.161140] [ 31.161140] the existing dependency chain (in reverse order) is: [ 31.162136] -> #2 (&pipe->mutex/1){+.+.+.}: [ 31.162912] lock_acquire+0x12e/0x410 [ 31.163489] mutex_lock_nested+0xbb/0x870 [ 31.164134] fifo_open+0x15c/0xa30 [ 31.164677] do_dentry_open+0x607/0xc60 [ 31.165275] vfs_open+0x105/0x220 [ 31.165804] path_openat+0x5ac/0x2910 [ 31.166380] do_filp_open+0x197/0x290 [ 31.166955] do_open_execat+0xfa/0x4d0 [ 31.167568] do_execveat_common.isra.37+0x6d6/0x1f10 [ 31.168309] compat_SyS_execve+0x48/0x60 [ 31.168917] do_fast_syscall_32+0x2f7/0x890 [ 31.169558] entry_SYSENTER_compat+0x51/0x60 [ 31.170205] -> #1 (&sig->cred_guard_mutex){+.+.+.}: [ 31.171029] lock_acquire+0x12e/0x410 [ 31.171604] mutex_lock_killable_nested+0xcc/0x960 [ 31.172337] lock_trace+0x44/0xc0 [ 31.172881] proc_pid_syscall+0xa6/0x260 [ 31.173488] proc_single_show+0xf8/0x170 [ 31.178033] seq_read+0x32f/0x1290 [ 31.182056] do_loop_readv_writev.part.17+0x141/0x1e0 [ 31.187731] compat_do_readv_writev+0x522/0x760 [ 31.192887] compat_readv+0xe3/0x150 [ 31.197085] do_compat_readv+0xf4/0x1d0 [ 31.201545] compat_SyS_readv+0x26/0x30 [ 31.206002] do_fast_syscall_32+0x2f7/0x890 [ 31.210808] entry_SYSENTER_compat+0x51/0x60 [ 31.215698] -> #0 (&p->lock){+.+.+.}: [ 31.220080] __lock_acquire+0x2bf9/0x3640 [ 31.224712] lock_acquire+0x12e/0x410 [ 31.228998] mutex_lock_nested+0xbb/0x870 [ 31.233628] seq_read+0xdd/0x1290 [ 31.237566] proc_reg_read+0xef/0x170 [ 31.241850] do_loop_readv_writev.part.17+0x141/0x1e0 [ 31.247522] do_readv_writev+0x520/0x750 [ 31.252065] vfs_readv+0x84/0xc0 [ 31.255916] default_file_splice_read+0x43f/0x7a0 [ 31.261249] do_splice_to+0x10a/0x160 [ 31.265536] SyS_splice+0xf5f/0x1520 [ 31.269733] do_fast_syscall_32+0x2f7/0x890 [ 31.274540] entry_SYSENTER_compat+0x51/0x60 [ 31.279430] [ 31.279430] other info that might help us debug this: [ 31.279430] [ 31.287533] Chain exists of: &p->lock --> &sig->cred_guard_mutex --> &pipe->mutex/1 [ 31.296509] Possible unsafe locking scenario: [ 31.296509] [ 31.302528] CPU0 CPU1 [ 31.307157] ---- ---- [ 31.311784] lock(&pipe->mutex/1); [ 31.315702] lock(&sig->cred_guard_mutex); [ 31.322727] lock(&pipe->mutex/1); [ 31.329172] lock(&p->lock); [ 31.332463] [ 31.332463] *** DEADLOCK *** [ 31.332463] [ 31.338485] 1 lock held by syzkaller689322/3350: [ 31.343202] #0: (&pipe->mutex/1){+.+.+.}, at: [] pipe_lock+0x56/0x70 [ 31.351953] [ 31.351953] stack backtrace: [ 31.356415] CPU: 1 PID: 3350 Comm: syzkaller689322 Not tainted 4.9.71-g2506378 #9 [ 31.363997] Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 [ 31.373319] ffff8801c90b7258 ffffffff81d922b9 ffffffff85363ea0 ffffffff853972c0 [ 31.381259] ffffffff8539c210 ffff8801c82850d8 ffff8801c8284800 ffff8801c90b72a0 [ 31.389201] ffffffff812367e1 ffff8801c82850d8 00000000c82850b0 ffff8801c82850d8 [ 31.397158] Call Trace: [ 31.399711] [] dump_stack+0xc1/0x128 [ 31.405040] [] print_circular_bug+0x271/0x310 [ 31.411149] [] __lock_acquire+0x2bf9/0x3640 [ 31.417084] [] ? debug_check_no_locks_freed+0x2c0/0x2c0 [ 31.424061] [] ? __lock_is_held+0xa1/0xf0 [ 31.429822] [] lock_acquire+0x12e/0x410 [ 31.435409] [] ? seq_read+0xdd/0x1290 [ 31.440821] [] ? seq_read+0xdd/0x1290 [ 31.446237] [] mutex_lock_nested+0xbb/0x870 [ 31.452173] [] ? seq_read+0xdd/0x1290 [ 31.457589] [] ? mutex_lock_killable_nested+0x960/0x960 [ 31.464566] [] ? mark_held_locks+0xaf/0x100 [ 31.470502] [] ? depot_save_stack+0x1c5/0x4a0 [ 31.476609] [] ? _raw_spin_unlock_irqrestore+0x5a/0x70 [ 31.483497] [] ? seq_escape+0x200/0x200 [ 31.489082] [] seq_read+0xdd/0x1290 [ 31.494323] [] ? _raw_spin_unlock_irqrestore+0x45/0x70 [ 31.501213] [] ? depot_save_stack+0x3b1/0x4a0 [ 31.507327] [] ? __lock_is_held+0xa1/0xf0 [ 31.513087] [] ? seq_escape+0x200/0x200 [ 31.518676] [] ? __fsnotify_parent+0xbc/0x340 [ 31.524784] [] ? fsnotify+0x86/0xf30 [ 31.530111] [] ? fsnotify+0xf30/0xf30 [ 31.535523] [] ? seq_escape+0x200/0x200 [ 31.541112] [] proc_reg_read+0xef/0x170 [ 31.546702] [] do_loop_readv_writev.part.17+0x141/0x1e0 [ 31.553679] [] ? security_file_permission+0x89/0x1e0 [ 31.560396] [] ? proc_reg_write+0x170/0x170 [ 31.566328] [] ? proc_reg_write+0x170/0x170 [ 31.572260] [] do_readv_writev+0x520/0x750 [ 31.578106] [] ? vfs_write+0x530/0x530 [ 31.583606] [] ? kasan_unpoison_shadow+0x35/0x50 [ 31.589975] [] ? push_pipe+0x372/0x770 [ 31.595474] [] ? sanity+0x1ff/0x610 [ 31.600713] [] ? iov_iter_get_pages_alloc+0x2c7/0xf10 [ 31.607514] [] vfs_readv+0x84/0xc0 [ 31.612667] [] default_file_splice_read+0x43f/0x7a0 [ 31.619297] [] ? do_splice_direct+0x270/0x270 [ 31.625408] [] ? debug_check_no_locks_freed+0x2c0/0x2c0 [ 31.632389] [] ? __fsnotify_parent+0xbc/0x340 [ 31.638498] [] ? fsnotify+0x86/0xf30 [ 31.643823] [] ? fsnotify+0xf30/0xf30 [ 31.649237] [] ? avc_policy_seqno+0x9/0x20 [ 31.655086] [] ? selinux_file_permission+0x82/0x460 [ 31.661713] [] ? security_file_permission+0x89/0x1e0 [ 31.668426] [] ? rw_verify_area+0xe5/0x2b0 [ 31.674279] [] ? do_splice_direct+0x270/0x270 [ 31.680386] [] do_splice_to+0x10a/0x160 [ 31.685974] [] SyS_splice+0xf5f/0x1520 [ 31.691473] [] ? compat_SyS_futex+0x1f9/0x2a0 [ 31.697585] [] ? compat_SyS_vmsplice+0x240/0x240 executing program [ 31.703954] [] ? do_fast_syscall_32+0xcf/0x890 [ 31.710149] [] ? compat_SyS_vmsplice+0x240/0x240 [ 31.716517] [] do_fast_syscall_32+0x2f7/0x890 [ 31.722625] [] ? trace_hardirqs_off_thunk+0x1a/0x1c [ 31.729254] [] entry_SYSENTER_compat+0x51/0x60 executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program