- Added a test case for #53437.

ext/date/tests/bug53437.phpt

@@ -0,0 +1,28 @@
+--TEST--
+Bug #53437: Crash when using unserialized DatePeriod instance
+--XFAIL--
+Bug #53437 Not fixed yet
+--FILE--
+<?php
+$dp = new DatePeriod(new DateTime('2010-01-01 UTC'), new DateInterval('P1D'), 2);
+
+echo "Original:\r\n";
+foreach($dp as $dt) {
+        echo $dt->format('Y-m-d H:i:s')."\r\n";
+}
+echo "\r\n";
+var_dump($dp);
+
+$ser = serialize($dp); // $ser is: O:10:"DatePeriod":0:{}
+
+// Create dangerous instance
+$dpu = unserialize($ser); // $dpu has invalid values???
+var_dump($dpu);
+
+echo "Unserialized:\r\n";
+// ???which leads to CRASH:
+foreach($dpu as $dt) {
+        echo $dt->format('Y-m-d H:i:s')."\r\n";
+}
+?>
+--EXPECT--