exec: Consolidate pdeath_signal clearing

Instead of an additional secureexec check for pdeath_signal, just move it
up into the initial secureexec test. Neither perf nor arch code touches
pdeath_signal, so the relocation shouldn't change anything.
Signed-off-by: Kees Cook <keescook@chromium.org>
Acked-by: Serge Hallyn <serge@hallyn.com>

fs/exec.c

@@ -1351,6 +1351,9 @@ void setup_new_exec(struct linux_binprm * bprm)
 	bprm->secureexec |= bprm->cap_elevated;
 
 	if (bprm->secureexec) {
+		/* Make sure parent cannot signal privileged process. */
+		current->pdeath_signal = 0;
+
 		/*
 		 * For secureexec, reset the stack limit to sane default to
 		 * avoid bad behavior from the prior rlimits. This has to
@@ -1383,10 +1386,6 @@ void setup_new_exec(struct linux_binprm * bprm)
 	 */
 	current->mm->task_size = TASK_SIZE;
 
-	if (bprm->secureexec) {
-		current->pdeath_signal = 0;
-	}
-
 	/* An exec changes our domain. We are no longer part of the thread
 	   group */
 	current->self_exec_id++;