Adapted for PHP 5.4.16 from 

From 56754a7f9eba0e4f559b6ca081d9f2a447b3f159 Mon Sep 17 00:00:00 2001
From: Stanislav Malyshev <stas@php.net>
Date: Sun, 28 Sep 2014 14:19:31 -0700
Subject: [PATCH] Fixed bug #68044: Integer overflow in unserialize() (32-bits
 only)

---
 NEWS                                       |  5 ++++-
 ext/standard/tests/serialize/bug68044.phpt | 12 ++++++++++++
 ext/standard/var_unserializer.c            |  4 ++--
 ext/standard/var_unserializer.re           |  2 +-
 4 files changed, 19 insertions(+), 4 deletions(-)
 create mode 100644 ext/standard/tests/serialize/bug68044.phpt

diff --git a/ext/standard/tests/serialize/bug68044.phpt b/ext/standard/tests/serialize/bug68044.phpt
new file mode 100644
index 0000000..031e44e
--- /dev/null
+++ b/ext/standard/tests/serialize/bug68044.phpt
@@ -0,0 +1,12 @@
+--TEST--
+Bug #68044 Integer overflow in unserialize() (32-bits only)
+--FILE--
+<?php
+	echo unserialize('C:3:"XYZ":18446744075857035259:{}');
+?>
+===DONE==
+--EXPECTF--
+Warning: Insufficient data for unserializing - %d required, 1 present in %s/bug68044.php on line 2
+
+Notice: unserialize(): Error at offset 32 of 33 bytes in %s/bug68044.php on line 2
+===DONE==
diff --git a/ext/standard/var_unserializer.c b/ext/standard/var_unserializer.c
index 657051f..8129da3 100644
--- a/ext/standard/var_unserializer.c
+++ b/ext/standard/var_unserializer.c
@@ -344,7 +344,7 @@ static inline int object_custom(UNSERIALIZE_PARAMETER, zend_class_entry *ce)
 
 	(*p) += 2;
 
-	if (datalen < 0 || (*p) + datalen >= max) {
+	if (datalen < 0 || (max - (*p)) <= datalen) {
 		zend_error(E_WARNING, "Insufficient data for unserializing - %ld required, %ld present", datalen, (long)(max - (*p)));
 		return 0;
 	}
diff --git a/ext/standard/var_unserializer.re b/ext/standard/var_unserializer.re
index 1307508..6de1583 100644
--- a/ext/standard/var_unserializer.re
+++ b/ext/standard/var_unserializer.re
@@ -350,7 +350,7 @@ static inline int object_custom(UNSERIALIZE_PARAMETER, zend_class_entry *ce)
 
 	(*p) += 2;
 
-	if (datalen < 0 || (*p) + datalen >= max) {
+	if (datalen < 0 || (max - (*p)) <= datalen) {
 		zend_error(E_WARNING, "Insufficient data for unserializing - %ld required, %ld present", datalen, (long)(max - (*p)));
 		return 0;
 	}
-- 
2.1.0