[....] Starting file context maintaining daemon: restorecond[?25l[?1c7[ ok 8[?25h[?0c. [....] Starting OpenBSD Secure Shell server: sshd[ 10.020673] random: sshd: uninitialized urandom read (32 bytes read) [?25l[?1c7[ ok 8[?25h[?0c. Debian GNU/Linux 7 syzkaller ttyS0 syzkaller login: [ 31.664821] random: sshd: uninitialized urandom read (32 bytes read) [ 32.051998] audit: type=1400 audit(1546948051.082:6): avc: denied { map } for pid=1761 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 [ 32.085393] random: sshd: uninitialized urandom read (32 bytes read) [ 32.509810] random: sshd: uninitialized urandom read (32 bytes read) Warning: Permanently added '10.128.10.45' (ECDSA) to the list of known hosts. [ 38.397940] urandom_read: 1 callbacks suppressed [ 38.397943] random: sshd: uninitialized urandom read (32 bytes read) executing program [ 38.486301] audit: type=1400 audit(1546948057.512:7): avc: denied { map } for pid=1773 comm="syz-executor095" path="/root/syz-executor095770029" dev="sda1" ino=16481 scontext=unconfined_u:system_r:insmod_t:s0-s0:c0.c1023 tcontext=unconfined_u:object_r:user_home_t:s0 tclass=file permissive=1 [ 38.536254] [ 38.538211] ====================================================== [ 38.544503] WARNING: possible circular locking dependency detected [ 38.550951] 4.14.91+ #3 Not tainted [ 38.554918] ------------------------------------------------------ [ 38.561773] syz-executor095/1775 is trying to acquire lock: [ 38.567471] (&pipe->mutex/1){+.+.}, at: [] fifo_open+0x156/0x9b0 [ 38.575260] [ 38.575260] but task is already holding lock: [ 38.581210] (&sig->cred_guard_mutex){+.+.}, at: [] prepare_bprm_creds+0x51/0x110 [ 38.590521] [ 38.590521] which lock already depends on the new lock. [ 38.590521] [ 38.599103] [ 38.599103] the existing dependency chain (in reverse order) is: [ 38.606958] [ 38.606958] -> #1 (&sig->cred_guard_mutex){+.+.}: [ 38.613258] [ 38.613258] -> #0 (&pipe->mutex/1){+.+.}: [ 38.618863] [ 38.618863] other info that might help us debug this: [ 38.618863] [ 38.627069] Possible unsafe locking scenario: [ 38.627069] [ 38.633317] CPU0 CPU1 [ 38.638289] ---- ---- [ 38.642938] lock(&sig->cred_guard_mutex); [ 38.647403] lock(&pipe->mutex/1); [ 38.653545] lock(&sig->cred_guard_mutex); [ 38.660366] lock(&pipe->mutex/1); [ 38.664034] [ 38.664034] *** DEADLOCK *** [ 38.664034] [ 38.670199] 1 lock held by syz-executor095/1775: [ 38.674939] #0: (&sig->cred_guard_mutex){+.+.}, at: [] prepare_bprm_creds+0x51/0x110 [ 38.684720] [ 38.684720] stack backtrace: [ 38.689208] CPU: 1 PID: 1775 Comm: syz-executor095 Not tainted 4.14.91+ #3 [ 38.696387] Call Trace: [ 38.698961] dump_stack+0xb9/0x10e [ 38.702487] print_circular_bug.isra.0.cold+0x2dc/0x425 [ 38.708014] ? __lock_acquire+0x2d83/0x3fa0 [ 38.712447] ? trace_hardirqs_on+0x10/0x10 [ 38.716744] ? _raw_spin_unlock_irqrestore+0x41/0x70 [ 38.722254] ? __lock_acquire+0x56a/0x3fa0 [ 38.726472] ? do_filp_open+0x1a1/0x280 [ 38.730508] ? lock_acquire+0x10f/0x380 [ 38.734593] ? fifo_open+0x156/0x9b0 [ 38.738297] ? fifo_open+0x156/0x9b0 [ 38.741988] ? __mutex_lock+0xf7/0x1430 [ 38.745943] ? fifo_open+0x156/0x9b0 [ 38.749640] ? fifo_open+0x156/0x9b0 [ 38.753339] ? __ww_mutex_wakeup_for_backoff+0x210/0x210 [ 38.758887] ? fifo_open+0x284/0x9b0 [ 38.762585] ? lock_downgrade+0x5d0/0x5d0 [ 38.766718] ? lock_acquire+0x10f/0x380 [ 38.770687] ? fifo_open+0x243/0x9b0 [ 38.774383] ? debug_mutex_init+0x28/0x53 [ 38.778864] ? fifo_open+0x156/0x9b0 [ 38.782663] ? fifo_open+0x156/0x9b0 [ 38.786475] ? do_dentry_open+0x41b/0xd60 [ 38.790610] ? pipe_release+0x240/0x240 [ 38.794728] ? vfs_open+0x105/0x230 [ 38.798442] ? path_openat+0xb6b/0x2b70 [ 38.802509] ? path_mountpoint+0x9a0/0x9a0 [ 38.806943] ? kasan_kmalloc.part.0+0xa6/0xd0 [ 38.811538] ? kasan_kmalloc.part.0+0x4f/0xd0 [ 38.816196] ? kmemdup+0x23/0x50 [ 38.819543] ? selinux_cred_prepare+0x3e/0x90 [ 38.824014] ? do_filp_open+0x1a1/0x280 [ 38.827964] ? prepare_bprm_creds+0x66/0x110 [ 38.832360] ? may_open_dev+0xe0/0xe0 [ 38.836151] ? rcu_lockdep_current_cpu_online+0xed/0x140 [ 38.841583] ? rcu_read_lock_sched_held+0x10a/0x130 [ 38.846577] ? do_open_execat+0xf7/0x5c0 [ 38.850775] ? setup_arg_pages+0x710/0x710 [ 38.854993] ? do_execveat_common.isra.0+0x674/0x1c30 [ 38.860174] ? lock_acquire+0x10f/0x380 [ 38.864138] ? do_execveat_common.isra.0+0x422/0x1c30 [ 38.869455] ? check_preemption_disabled+0x35/0x1f0 [ 38.874587] ? do_execveat_common.isra.0+0x6b3/0x1c30 [ 38.879754] ? prepare_bprm_creds+0x110/0x110 [ 38.884345] ? getname_flags+0x22e/0x550