random: sshd: uninitialized urandom read (32 bytes read) audit: type=1400 audit(1547466344.967:7): avc: denied { map } for pid=1779 comm="syz-executor260" path="/root/syz-executor260775650" 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 ====================================================== WARNING: possible circular locking dependency detected 4.14.93+ #6 Not tainted ------------------------------------------------------ syz-executor260/1781 is trying to acquire lock: (&pipe->mutex/1){+.+.}, at: [] __pipe_lock fs/pipe.c:88 [inline] (&pipe->mutex/1){+.+.}, at: [] fifo_open+0x156/0x9b0 fs/pipe.c:921 but task is already holding lock: (&sig->cred_guard_mutex){+.+.}, at: [] prepare_bprm_creds+0x51/0x110 fs/exec.c:1389 which lock already depends on the new lock. the existing dependency chain (in reverse order) is: -> #1 (&sig->cred_guard_mutex){+.+.}: -> #0 (&pipe->mutex/1){+.+.}: other info that might help us debug this: Possible unsafe locking scenario: CPU0 CPU1 ---- ---- lock(&sig->cred_guard_mutex); lock(&pipe->mutex/1); lock(&sig->cred_guard_mutex); lock(&pipe->mutex/1); *** DEADLOCK *** 1 lock held by syz-executor260/1781: #0: (&sig->cred_guard_mutex){+.+.}, at: [] prepare_bprm_creds+0x51/0x110 fs/exec.c:1389 stack backtrace: CPU: 1 PID: 1781 Comm: syz-executor260 Not tainted 4.14.93+ #6 Call Trace: __dump_stack lib/dump_stack.c:17 [inline] dump_stack+0xb9/0x10e lib/dump_stack.c:53 print_circular_bug.isra.0.cold+0x2dc/0x425 kernel/locking/lockdep.c:1258 ? SyS_exec