Fixed oss-fuzz #56931

Author: derickr

ext/date/php_date.c

@@ -568,7 +568,7 @@ PHPAPI timelib_tzinfo *get_timezone_info(void)
 
 static void update_property(zend_object *object, zend_string *key, zval *prop_val)
 {
-	if (ZSTR_VAL(key)[0] == '\0') { // not public
+	if (ZSTR_LEN(key) > 0 && ZSTR_VAL(key)[0] == '\0') { // not public
 		const char *class_name, *prop_name;
 		size_t prop_name_len;
 

ext/date/tests/ossfuzz-56931.txt

@@ -0,0 +1 @@
+|O:12:"DateInterval":1:{s:0:"";s:2:"  ";

ext/date/tests/unserialize-test.phpt

@@ -6,6 +6,7 @@ $files = [
 	'ossfuzz-55589.txt',
 	'ossfuzz-55599.txt',
 	'ossfuzz-55727.txt',
+	'ossfuzz-56931.txt',
 ];
 
 foreach ($files as $file) {
@@ -24,16 +25,23 @@ foreach ($files as $file) {
 ?>
 --EXPECTF--
 ossfuzz-55589.txt: 
-%s: unserialize(): Error at offset 39 of 39 bytes in %sunserialize-test.php on line 14
+%s: unserialize(): Error at offset 39 of 39 bytes in %sunserialize-test.php on line %d
 bool(false)
 
 
 ossfuzz-55599.txt: 
-%s: unserialize(): Error at offset 26 of 26 bytes in %sunserialize-test.php on line 14
+%s: unserialize(): Error at offset 26 of 26 bytes in %sunserialize-test.php on line %d
 Error: Invalid serialization data for DateTime object
 bool(false)
 
 
 ossfuzz-55727.txt: 
-%s: unserialize(): Error at offset 230 of 509 bytes in %sunserialize-test.php on line 14
+%s: unserialize(): Error at offset 230 of 509 bytes in %sunserialize-test.php on line %d
+bool(false)
+
+
+ossfuzz-56931.txt: 
+Notice: unserialize(): Error at offset 39 of 39 bytes in %sunserialize-test.php on line %d
+
+Deprecated: Creation of dynamic property DateInterval::$ is deprecated in %s on line %d
 bool(false)