[ARM] Fix ARM signal handling.

If we are unable to deliver a signal to the process (eg, due to stack
pointer corruption) block the signal so other fatal signals can kill
off the process.

arch/arm/kernel/signal.c

@@ -497,11 +497,10 @@ handle_signal(unsigned long sig, siginfo_t *info, sigset_t *oldset,
 	 */
 	ret |= !valid_user_regs(regs);
 
-	if (ret == 0) {
-		if (ka->sa.sa_flags & SA_ONESHOT)
-			ka->sa.sa_handler = SIG_DFL;
-
-		if (!(ka->sa.sa_flags & SA_NODEFER)) {
+	/*
+	 * Block the signal if we were unsuccessful.
+	 */
+	if (ret != 0 || !(ka->sa.sa_flags & SA_NODEFER)) {
 		spin_lock_irq(&tsk->sighand->siglock);
 		sigorsets(&tsk->blocked, &tsk->blocked,
 			  &ka->sa.sa_mask);
@@ -509,6 +508,10 @@ handle_signal(unsigned long sig, siginfo_t *info, sigset_t *oldset,
 		recalc_sigpending();
 		spin_unlock_irq(&tsk->sighand->siglock);
 	}
+
+	if (ret == 0) {
+		if (ka->sa.sa_flags & SA_ONESHOT)
+			ka->sa.sa_handler = SIG_DFL;
 		return;
 	}