Backported from 5.6.25 by Remi.

From db38282f421a5d552840aeac807efc2f584162d2 Mon Sep 17 00:00:00 2001
From: Stanislav Malyshev <stas@php.net>
Date: Thu, 4 Aug 2016 00:17:42 -0700
Subject: [PATCH] Fix bug #72749: wddx_deserialize allows illegal memory access

---
 ext/wddx/tests/bug72749.phpt | 34 ++++++++++++++++++++++++++++++++++
 ext/wddx/wddx.c              | 20 ++++++++++++++------
 2 files changed, 48 insertions(+), 6 deletions(-)
 create mode 100644 ext/wddx/tests/bug72749.phpt

diff --git a/ext/wddx/tests/bug72749.phpt b/ext/wddx/tests/bug72749.phpt
new file mode 100644
index 0000000..ee17d0f
--- /dev/null
+++ b/ext/wddx/tests/bug72749.phpt
@@ -0,0 +1,34 @@
+--TEST--
+Bug #72749: wddx_deserialize allows illegal memory access
+--SKIPIF--
+<?php
+if (!extension_loaded('wddx')) {
+    die('skip. wddx not available');
+}
+?>
+--FILE--
+<?php
+$xml = <<<XML
+<?xml version='1.0'?>
+<!DOCTYPE wddxPacket SYSTEM 'wddx_0100.dtd'>
+<wddxPacket version='1.0'>
+<header/>
+        <data>
+                <struct>
+                     <var name='aDateTime3'>
+                         <dateTime>2\r2004-09-10T05:52:49+00</dateTime>
+                     </var>
+                 </struct>
+        </data>
+</wddxPacket>
+XML;
+
+$array = wddx_deserialize($xml);
+var_dump($array);
+?>
+--EXPECT--
+array(1) {
+  ["aDateTime3"]=>
+  string(24) "2
+2004-09-10T05:52:49+00"
+}
diff --git a/ext/wddx/wddx.c b/ext/wddx/wddx.c
index cde3e07..faadbfe1 100644
--- a/ext/wddx/wddx.c
+++ b/ext/wddx/wddx.c
@@ -1116,18 +1116,26 @@ static void php_wddx_process_data(void *user_data, const XML_Char *s, int len)
 			case ST_DATETIME: {
 				char *tmp;
 
-				tmp = emalloc(len + 1);
-				memcpy(tmp, s, len);
+				if (Z_TYPE_P(ent->data) == IS_STRING) {
+					tmp = safe_emalloc(Z_STRLEN_P(ent->data), 1, (size_t)len + 1);
+					memcpy(tmp, Z_STRVAL_P(ent->data), Z_STRLEN_P(ent->data));
+					memcpy(tmp + Z_STRLEN_P(ent->data), s, len);
+					len += Z_STRLEN_P(ent->data);
+					efree(Z_STRVAL_P(ent->data));
+					Z_TYPE_P(ent->data) = IS_LONG;
+				} else {
+					tmp = emalloc(len + 1);
+					memcpy(tmp, s, len);
+				}
 				tmp[len] = '\0';
 
 				Z_LVAL_P(ent->data) = php_parse_date(tmp, NULL);
 				/* date out of range < 1969 or > 2038 */
 				if (Z_LVAL_P(ent->data) == -1) {
-					Z_TYPE_P(ent->data) = IS_STRING;
-					Z_STRLEN_P(ent->data) = len;
-					Z_STRVAL_P(ent->data) = estrndup(s, len);
+					ZVAL_STRINGL(ent->data, tmp, len, 0);
+				} else {
+					efree(tmp);
 				}
-				efree(tmp);
 			}
 				break;