======================================================
WARNING: possible circular locking dependency detected
4.14.135+ #24 Not tainted
------------------------------------------------------
syz-executor.5/6674 is trying to acquire lock:
 (&p->lock){+.+.}, at: [<000000005f97c41c>] seq_read+0xcd/0x1180 fs/seq_file.c:165

but task is already holding lock:
 (&sig->cred_guard_mutex){+.+.}, at: [<000000009cb5d059>] 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 (&p->lock){+.+.}:

other info that might help us debug this:

 Possible unsafe locking scenario:

       CPU0                    CPU1
       ----                    ----
  lock(&sig->cred_guard_mutex);
                               lock(&p->lock);
                               lock(&sig->cred_guard_mutex);
  lock(&p->lock);

 *** DEADLOCK ***

1 lock held by syz-executor.5/6674:
 #0:  (&sig->cred_guard_mutex){+.+.}, at: [<000000009cb5d059>] prepare_bprm_creds+0x51/0x110 fs/exec.c:1389

stack backtrace:
CPU: 1 PID: 6674 Comm: syz-executor.5 Not tainted 4.14.135+ #24
Call Trace:
 __dump_stack lib/dump_stack.c:17 [inline]
 dump_stack+0xca/0x134 lib/dump_stack.c:53
 print_circular_bug.isra.0.cold+0x2dc/0x425 kernel/locking/lockdep.c:1258