[ 44.982216] audit: type=1800 audit(1550596700.442:30): pid=8134 uid=0 auid=4294967295 ses=4294967295 subj=system_u:system_r:kernel_t:s0 op=collect_data cause=failed(directio) comm="startpar" name="mcstrans" dev="sda1" ino=2457 res=0 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. Debian GNU/Linux 7 syzkaller ttyS0 syzkaller login: [ 49.414162] kauditd_printk_skb: 4 callbacks suppressed [ 49.414186] audit: type=1400 audit(1550596704.892:35): avc: denied { map } for pid=8310 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 '10.128.0.4' (ECDSA) to the list of known hosts. executing program [ 56.132185] audit: type=1400 audit(1550596711.612:36): avc: denied { map } for pid=8322 comm="syz-executor500" path="/root/syz-executor500470831" dev="sda1" ino=16483 scontext=unconfined_u:system_r:insmod_t:s0-s0:c0.c1023 tcontext=unconfined_u:object_r:user_home_t:s0 tclass=file permissive=1 [ 56.252735] [ 56.254386] ====================================================== [ 56.260681] WARNING: possible circular locking dependency detected [ 56.266974] 5.0.0-rc7+ #78 Not tainted [ 56.270834] ------------------------------------------------------ [ 56.277145] syz-executor500/8326 is trying to acquire lock: [ 56.282837] 00000000d2f4dc32 (&sig->cred_guard_mutex){+.+.}, at: proc_pid_attr_write+0x1fa/0x530 [ 56.291758] [ 56.291758] but task is already holding lock: [ 56.297704] 00000000ddeb029d (&pipe->mutex/1){+.+.}, at: pipe_lock+0x6e/0x80 [ 56.304908] [ 56.304908] which lock already depends on the new lock. [ 56.304908] [ 56.313334] [ 56.313334] the existing dependency chain (in reverse order) is: [ 56.320957] [ 56.320957] -> #1 (&pipe->mutex/1){+.+.}: [ 56.326589] __mutex_lock+0xf7/0x1310 [ 56.330906] mutex_lock_nested+0x16/0x20 [ 56.335470] fifo_open+0x159/0xb00 [ 56.339513] do_dentry_open+0x47d/0x1130 [ 56.344074] vfs_open+0xa0/0xd0 [ 56.347854] path_openat+0x10d7/0x4690 [ 56.352263] do_filp_open+0x1a1/0x280 [ 56.356579] do_open_execat+0x13b/0x6d0 [ 56.361148] __do_execve_file.isra.0+0x178d/0x23f0 [ 56.366578] __x64_sys_execve+0x8f/0xc0 [ 56.371064] do_syscall_64+0x103/0x610 [ 56.375451] entry_SYSCALL_64_after_hwframe+0x49/0xbe [ 56.381140] [ 56.381140] -> #0 (&sig->cred_guard_mutex){+.+.}: [ 56.387445] lock_acquire+0x16f/0x3f0 [ 56.391750] __mutex_lock+0xf7/0x1310 [ 56.396060] mutex_lock_interruptible_nested+0x16/0x20 [ 56.401855] proc_pid_attr_write+0x1fa/0x530 [ 56.406765] __vfs_write+0x116/0x8e0 [ 56.410988] __kernel_write+0x110/0x3b0 [ 56.415477] write_pipe_buf+0x15d/0x1f0 [ 56.419971] __splice_from_pipe+0x39a/0x7e0 [ 56.424806] splice_from_pipe+0x108/0x170 [ 56.429474] default_file_splice_write+0x3c/0x90 [ 56.434740] do_splice+0x644/0x1330 [ 56.438888] __x64_sys_splice+0x2c6/0x330 [ 56.443564] do_syscall_64+0x103/0x610 [ 56.447998] entry_SYSCALL_64_after_hwframe+0x49/0xbe [ 56.453698] [ 56.453698] other info that might help us debug this: [ 56.453698] [ 56.461829] Possible unsafe locking scenario: [ 56.461829] [ 56.467875] CPU0 CPU1 [ 56.472533] ---- ---- [ 56.477184] lock(&pipe->mutex/1); [ 56.480830] lock(&sig->cred_guard_mutex); [ 56.487746] lock(&pipe->mutex/1); [ 56.493886] lock(&sig->cred_guard_mutex); [ 56.498199] [ 56.498199] *** DEADLOCK *** [ 56.498199] [ 56.504428] 2 locks held by syz-executor500/8326: [ 56.509260] #0: 00000000de0f3543 (sb_writers#7){.+.+}, at: do_splice+0xceb/0x1330 [ 56.516992] #1: 00000000ddeb029d (&pipe->mutex/1){+.+.}, at: pipe_lock+0x6e/0x80 [ 56.524621] [ 56.524621] stack backtrace: [ 56.529115] CPU: 1 PID: 8326 Comm: syz-executor500 Not tainted 5.0.0-rc7+ #78 [ 56.536378] Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 [ 56.545721] Call Trace: [ 56.548312] dump_stack+0x172/0x1f0 [ 56.551945] print_circular_bug.isra.0.cold+0x1cc/0x28f [ 56.557309] __lock_acquire+0x2f00/0x4700 [ 56.561556] ? trace_hardirqs_on+0x67/0x230 [ 56.565871] ? kasan_check_read+0x11/0x20 [ 56.570021] ? mark_held_locks+0x100/0x100 [ 56.574259] ? __kmalloc_track_caller+0x158/0x740 [ 56.579097] ? memdup_user+0x26/0xb0 [ 56.583227] ? proc_pid_attr_write+0x196/0x530 [ 56.587802] ? __vfs_write+0x116/0x8e0 [ 56.591688] ? __kernel_write+0x110/0x3b0 [ 56.595916] ? write_pipe_buf+0x15d/0x1f0 [ 56.600084] ? __splice_from_pipe+0x39a/0x7e0 [ 56.604580] ? __lock_is_held+0xb6/0x140 [ 56.608650] ? proc_pid_attr_write+0x1fa/0x530 [ 56.613234] lock_acquire+0x16f/0x3f0 [ 56.617042] ? proc_pid_attr_write+0x1fa/0x530 [ 56.621624] ? proc_pid_attr_write+0x1fa/0x530 [ 56.626206] __mutex_lock+0xf7/0x1310 [ 56.630003] ? proc_pid_attr_write+0x1fa/0x530 [ 56.634668] ? proc_pid_attr_write+0x1fa/0x530 [ 56.639253] ? check_preemption_disabled+0x48/0x290 [ 56.644265] ? mutex_trylock+0x1e0/0x1e0 [ 56.648328] ? rcu_lockdep_current_cpu_online+0xe3/0x130 [ 56.653778] ? check_stack_object+0x114/0x160 [ 56.658272] ? __sanitizer_cov_trace_const_cmp8+0x18/0x20 [ 56.663805] ? __sanitizer_cov_trace_const_cmp8+0x18/0x20 [ 56.669351] ? __sanitizer_cov_trace_const_cmp8+0x18/0x20 [ 56.674883] ? __sanitizer_cov_trace_const_cmp8+0x18/0x20 [ 56.680422] ? _copy_from_user+0xdd/0x150 [ 56.684573] mutex_lock_interruptible_nested+0x16/0x20 [ 56.689851] ? mutex_lock_interruptible_nested+0x16/0x20 [ 56.695300] proc_pid_attr_write+0x1fa/0x530 [ 56.699712] __vfs_write+0x116/0x8e0 [ 56.703426] ? proc_loginuid_write+0x4d0/0x4d0 [ 56.708002] ? kernel_read+0x120/0x120 [ 56.711886] ? lock_pi_update_atomic+0x120/0x120 [ 56.716643] ? __lock_is_held+0xb6/0x140 [ 56.720699] ? lock_acquire+0x16f/0x3f0 [ 56.724673] __kernel_write+0x110/0x3b0 [ 56.728650] write_pipe_buf+0x15d/0x1f0 [ 56.732784] ? do_splice_direct+0x2a0/0x2a0 [ 56.737106] ? __sanitizer_cov_trace_const_cmp4+0x16/0x20 [ 56.742641] ? splice_from_pipe_next.part.0+0x255/0x2f0 [ 56.748004] __splice_from_pipe+0x39a/0x7e0 [ 56.752612] ? do_splice_direct+0x2a0/0x2a0 [ 56.756933] ? do_splice_direct+0x2a0/0x2a0 [ 56.761248] splice_from_pipe+0x108/0x170 [ 56.765389] ? splice_shrink_spd+0xd0/0xd0 [ 56.769623] ? __lock_is_held+0xb6/0x140 [ 56.773682] ? rcu_lockdep_current_cpu_online+0xe3/0x130 [ 56.779131] default_file_splice_write+0x3c/0x90 [ 56.783882] ? generic_splice_sendpage+0x50/0x50 [ 56.788631] do_splice+0x644/0x1330 [ 56.792263] ? iterate_fd+0x360/0x360 [ 56.796474] ? opipe_prep.part.0+0x2d0/0x2d0 [ 56.800883] ? __fget_light+0x1a9/0x230 [ 56.804857] __x64_sys_splice+0x2c6/0x330 [ 56.809009] do_syscall_64+0x103/0x610 [ 56.812899] entry_SYSCALL_64_after_hwframe+0x49/0xbe [ 56.818082] RIP: 0033:0x445779 [ 56.821269] 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 [ 56.840169] RSP: 002b:00007fc0eefecda8 EFLAGS: 00000246 ORIG_RAX: 0000000000000113 [ 56.847877] RAX: ffffffffffffffda RBX: 00000000006dac68 RCX: 0000000000445779 [ 56.855141] RDX: 0000000000000005 RSI: 0000000000000000 RDI: 0000000000000003 [ 56.862408] RBP: 00000000006dac60 R08: 0000020000000003 R09: 0000000000000009 [ 56.869669] R10: 0000000000000000 R11: 0000000000000246 R12: 00000000006dac6c [ 56.876936] R13: 00007ffdca50374f R14: 00007fc0eefed9c0 R15: 20c49ba5e353f7cf