Fix bug #73147: Use After Free in PHP7 unserialize()

Zend/zend_API.c

@@ -3776,6 +3776,30 @@ ZEND_API void zend_update_property(zend_class_entry *scope, zval *object, const
 }
 /* }}} */
 
+ZEND_API void zend_unset_property(zend_class_entry *scope, zval *object, const char *name, int name_length TSRMLS_DC) /* {{{ */
+{
+	zval *property;
+	zend_class_entry *old_scope = EG(scope);
+
+	EG(scope) = scope;
+
+	if (!Z_OBJ_HT_P(object)->unset_property) {
+		const char *class_name;
+		zend_uint class_name_len;
+
+		zend_get_object_classname(object, &class_name, &class_name_len TSRMLS_CC);
+
+		zend_error(E_CORE_ERROR, "Property %s of class %s cannot be unset", name, class_name);
+	}
+	MAKE_STD_ZVAL(property);
+	ZVAL_STRINGL(property, name, name_length, 1);
+	Z_OBJ_HT_P(object)->unset_property(object, property, 0 TSRMLS_CC);
+	zval_ptr_dtor(&property);
+
+	EG(scope) = old_scope;
+}
+/* }}} */
+
 ZEND_API void zend_update_property_null(zend_class_entry *scope, zval *object, const char *name, int name_length TSRMLS_DC) /* {{{ */
 {
 	zval *tmp;

Zend/zend_API.h

@@ -330,6 +330,7 @@ ZEND_API void zend_update_property_long(zend_class_entry *scope, zval *object, c
 ZEND_API void zend_update_property_double(zend_class_entry *scope, zval *object, const char *name, int name_length, double value TSRMLS_DC);
 ZEND_API void zend_update_property_string(zend_class_entry *scope, zval *object, const char *name, int name_length, const char *value TSRMLS_DC);
 ZEND_API void zend_update_property_stringl(zend_class_entry *scope, zval *object, const char *name, int name_length, const char *value, int value_length TSRMLS_DC);
+ZEND_API void zend_unset_property(zend_class_entry *scope, zval *object, const char *name, int name_length TSRMLS_DC);
 
 ZEND_API int zend_update_static_property(zend_class_entry *scope, const char *name, int name_length, zval *value TSRMLS_DC);
 ZEND_API int zend_update_static_property_null(zend_class_entry *scope, const char *name, int name_length TSRMLS_DC);

ext/curl/curl_file.c

@@ -137,7 +137,10 @@ ZEND_METHOD(CURLFile, setPostFilename)
    Unserialization handler */
 ZEND_METHOD(CURLFile, __wakeup)
 {
-	zend_update_property_string(curl_CURLFile_class, getThis(), "name", sizeof("name")-1, "" TSRMLS_CC);
+	zval *_this = getThis();
+
+	zend_unset_property(curl_CURLFile_class, _this, "name", sizeof("name")-1 TSRMLS_CC);
+	zend_update_property_string(curl_CURLFile_class, _this, "name", sizeof("name")-1, "" TSRMLS_CC);
 	zend_throw_exception(NULL, "Unserialization of CURLFile instances is not allowed", 0 TSRMLS_CC);
 }
 /* }}} */

ext/curl/tests/bug73147.phpt

@@ -0,0 +1,20 @@
+--TEST--
+Bug #73147: Use After Free in PHP7 unserialize()
+--SKIPIF--
+<?php
+if (!extension_loaded("curl")) {
+        exit("skip curl extension not loaded");
+}
+?>
+--FILE--
+<?php
+
+$poc = 'a:1:{i:0;O:8:"CURLFile":1:{s:4:"name";R:1;}}';
+try {
+var_dump(unserialize($poc));
+} catch(Exception $e) {
+	echo $e->getMessage();
+}
+?>
+--EXPECT--
+Unserialization of CURLFile instances is not allowed