CVE-2016-9934 (published 2017-01-04T20:59Z)

ext/wddx/wddx.c in PHP before 5.6.28 and 7.x before 7.0.13 allows remote attackers to cause a denial of service (NULL pointer dereference) via crafted serialized data in a wddxPacket XML document, as demonstrated by a PDORow string.

Severity: MEDIUM
CVSS v2 base score: 5.0 (AV:N/AC:L/Au:N/C:N/I:N/A:P)
CVSS v3 base score: 7.5, HIGH (CVSS:3.0/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H)

Weakness information:
cwe_id: CWE-476
cwe_name: NULL Pointer Dereference
description: The product dereferences a pointer that it expects to be valid but is NULL.
extended_description: 
            
            
            
         
         

Fix information:
repo_url: https://github.com/php/php-src
commit_details: repo_url: https://github.com/php/php-src
author: Stanislav Malyshev
author_date: 2016-10-23 20:07:47-07:00
msg: Fix bug #73331 - do not try to serialize/unserialize objects wddx can not handle

Proper soltion would be to call serialize/unserialize and deal with the result,
but this requires more work that should be done by wddx maintainer (not me).
repository: repo_url: https://github.com/php/php-src
repo_name: php/php-src
description: The PHP Interpreter
repo_language: C
owner: php
file_changes: filename: pdo_stmt.c
change_type: ModificationType.MODIFY
diff: @@ -2338,6 +2338,7 @@ void pdo_stmt_init(TSRMLS_D)
 	pdo_row_ce->ce_flags |= ZEND_ACC_FINAL_CLASS; /* when removing this a lot of handlers need to be redone */
 	pdo_row_ce->create_object = pdo_row_new;
 	pdo_row_ce->serialize = pdo_row_serialize;
+	pdo_row_ce->unserialize = zend_class_unserialize_deny;
 }
 
 static void free_statement(pdo_stmt_t *stmt TSRMLS_DC)

programming_language: C
filename: bug45901.phpt
change_type: ModificationType.MODIFY
diff: @@ -14,5 +14,7 @@
 echo "DONE";
 ?>
 --EXPECTF--
-<wddxPacket version='1.0'><header><comment>Variables</comment></header><data><struct><var name='php_class_name'><string>SimpleXMLElement</string></var><var name='test'><struct><var name='php_class_name'><string>SimpleXMLElement</string></var></struct></var></struct></data></wddxPacket>
+
+Warning: wddx_serialize_value(): Class SimpleXMLElement can not be serialized in %sbug45901.php on line %d
+<wddxPacket version='1.0'><header><comment>Variables</comment></header><data></data></wddxPacket>
 DONE
\ No newline at end of file

programming_language: PHP
filename: bug72790.phpt
change_type: ModificationType.MODIFY
diff: @@ -1,5 +1,5 @@
 --TEST--
-Bug 72790: wddx_deserialize null dereference with invalid xml
+Bug #72790: wddx_deserialize null dereference with invalid xml
 --SKIPIF--
 <?php
 if (!extension_loaded('wddx')) {

programming_language: PHP
filename: bug73331.phpt
change_type: ModificationType.ADD
diff: @@ -0,0 +1,15 @@
+--TEST--
+Bug #73331 (NULL Pointer Dereference in WDDX Packet Deserialization with PDORow)
+--SKIPIF--
+<?php if (!extension_loaded("wddx") || !extension_loaded("pdo")) print "skip"; ?>
+--FILE--
+<?php
+
+$wddx = "<wddxPacket version='1.0'><header/><data><struct><var name='php_class_name'><string>PDORow</string></var></struct></data></wddxPacket>";
+var_dump(wddx_deserialize($wddx));
+?>
+--EXPECTF--
+
+Warning: wddx_deserialize(): Class pdorow can not be unserialized in %s73331.php on line %d
+NULL
+

programming_language: PHP
filename: wddx.c
change_type: ModificationType.MODIFY
diff: @@ -471,21 +471,26 @@ static void php_wddx_serialize_object(wddx_packet *packet, zval *obj)
 	ulong idx;
 	char tmp_buf[WDDX_BUF_LEN];
 	HashTable *objhash, *sleephash;
+	zend_class_entry *ce;
+	PHP_CLASS_ATTRIBUTES;
 	TSRMLS_FETCH();
 
+	PHP_SET_CLASS_ATTRIBUTES(obj);
+	ce = Z_OBJCE_P(obj);
+	if (!ce || ce->serialize || ce->unserialize) {
+		php_error_docref(NULL TSRMLS_CC, E_WARNING, "Class %s can not be serialized", class_name);
+		PHP_CLEANUP_CLASS_ATTRIBUTES();
+		return;
+	}
+
 	MAKE_STD_ZVAL(fname);
 	ZVAL_STRING(fname, "__sleep", 1);
-
 	/*
 	 * We try to call __sleep() method on object. It's supposed to return an
 	 * array of property names to be serialized.
 	 */
 	if (call_user_function_ex(CG(function_table), &obj, fname, &retval, 0, 0, 1, NULL TSRMLS_CC) == SUCCESS) {
 		if (retval && (sleephash = HASH_OF(retval))) {
-			PHP_CLASS_ATTRIBUTES;
-
-			PHP_SET_CLASS_ATTRIBUTES(obj);
-
 			php_wddx_add_chunk_static(packet, WDDX_STRUCT_S);
 			snprintf(tmp_buf, WDDX_BUF_LEN, WDDX_VAR_S, PHP_CLASS_NAME_VAR);
 			php_wddx_add_chunk(packet, tmp_buf);
@@ -494,8 +499,6 @@ static void php_wddx_serialize_object(wddx_packet *packet, zval *obj)
 			php_wddx_add_chunk_static(packet, WDDX_STRING_E);
 			php_wddx_add_chunk_static(packet, WDDX_VAR_E);
 
-			PHP_CLEANUP_CLASS_ATTRIBUTES();
-
 			objhash = HASH_OF(obj);
 
 			for (zend_hash_internal_pointer_reset(sleephash);
@@ -516,10 +519,6 @@ static void php_wddx_serialize_object(wddx_packet *packet, zval *obj)
 	} else {
 		uint key_len;
 
-		PHP_CLASS_ATTRIBUTES;
-
-		PHP_SET_CLASS_ATTRIBUTES(obj);
-
 		php_wddx_add_chunk_static(packet, WDDX_STRUCT_S);
 		snprintf(tmp_buf, WDDX_BUF_LEN, WDDX_VAR_S, PHP_CLASS_NAME_VAR);
 		php_wddx_add_chunk(packet, tmp_buf);
@@ -528,8 +527,6 @@ static void php_wddx_serialize_object(wddx_packet *packet, zval *obj)
 		php_wddx_add_chunk_static(packet, WDDX_STRING_E);
 		php_wddx_add_chunk_static(packet, WDDX_VAR_E);
 
-		PHP_CLEANUP_CLASS_ATTRIBUTES();
-
 		objhash = HASH_OF(obj);
 		for (zend_hash_internal_pointer_reset(objhash);
 			 zend_hash_get_current_data(objhash, (void**)&ent) == SUCCESS;
@@ -551,6 +548,8 @@ static void php_wddx_serialize_object(wddx_packet *packet, zval *obj)
 		php_wddx_add_chunk_static(packet, WDDX_STRUCT_E);
 	}
 
+	PHP_CLEANUP_CLASS_ATTRIBUTES();
+
 	zval_dtor(fname);
 	FREE_ZVAL(fname);
 
@@ -1012,26 +1011,30 @@ static void php_wddx_pop_element(void *user_data, const XML_Char *name)
 							pce = &PHP_IC_ENTRY;
 						}
 
-						/* Initialize target object */
-						MAKE_STD_ZVAL(obj);
-						object_init_ex(obj, *pce);
-
-						/* Merge current hashtable with object's default properties */
-						zend_hash_merge(Z_OBJPROP_P(obj),
-										Z_ARRVAL_P(ent2->data),
-										(void (*)(void *)) zval_add_ref,
-										(void *) &tmp, sizeof(zval *), 0);
-
-						if (incomplete_class) {
-							php_store_class_name(obj, Z_STRVAL_P(ent1->data), Z_STRLEN_P(ent1->data));
+						if (pce != &PHP_IC_ENTRY && ((*pce)->serialize || (*pce)->unserialize)) {
+							ent2->data = NULL;
+							php_error_docref(NULL TSRMLS_CC, E_WARNING, "Class %s can not be unserialized", Z_STRVAL_P(ent1->data));
+						} else {
+							/* Initialize target object */
+							MAKE_STD_ZVAL(obj);
+							object_init_ex(obj, *pce);
+
+							/* Merge current hashtable with object's default properties */
+							zend_hash_merge(Z_OBJPROP_P(obj),
+											Z_ARRVAL_P(ent2->data),
+											(void (*)(void *)) zval_add_ref,
+											(void *) &tmp, sizeof(zval *), 0);
+
+							if (incomplete_class) {
+								php_store_class_name(obj, Z_STRVAL_P(ent1->data), Z_STRLEN_P(ent1->data));
+							}
+
+							/* Clean up old array entry */
+							zval_ptr_dtor(&ent2->data);
+
+							/* Set stack entry to point to the newly created object */
+							ent2->data = obj;
 						}
-
-						/* Clean up old array entry */
-						zval_ptr_dtor(&ent2->data);
-
-						/* Set stack entry to point to the newly created object */
-						ent2->data = obj;
-
 						/* Clean up class name var entry */
 						zval_ptr_dtor(&ent1->data);
 					} else if (Z_TYPE_P(ent2->data) == IS_OBJECT) {

programming_language: C