round(): Validate the rounding mode

Author: TimWolla

ext/standard/math.c

@@ -335,6 +335,17 @@ PHP_FUNCTION(round)
 		}
 	}
 
+	switch (mode) {
+		case PHP_ROUND_HALF_UP:
+		case PHP_ROUND_HALF_DOWN:
+		case PHP_ROUND_HALF_EVEN:
+		case PHP_ROUND_HALF_ODD:
+			break;
+		default:
+			zend_argument_value_error(3, "must be a valid rounding mode (PHP_ROUND_*)");
+			RETURN_THROWS();
+	}
+
 	switch (Z_TYPE_P(value)) {
 		case IS_LONG:
 			/* Simple case - long that doesn't need to be rounded. */