Fix bug #72434: ZipArchive class Use After Free Vulnerability in PHP'…

…s GC algorithm and unserialize

ext/standard/tests/strings/bug72434.phpt

@@ -0,0 +1,33 @@
+--TEST--
+Bug #72434: ZipArchive class Use After Free Vulnerability in PHP's GC algorithm and unserialize
+--SKIPIF--
+<?php
+if(!class_exists('zip')) die('ZipArchive');
+?>
+--FILE--
+<?php
+// The following array will be serialized and this representation will be freed later on.
+$free_me = array(new StdClass());
+// Create our payload and unserialize it.
+$serialized_payload = 'a:3:{i:1;N;i:2;O:10:"ZipArchive":1:{s:8:"filename";'.serialize($free_me).'}i:1;R:4;}';
+$unserialized_payload = unserialize($serialized_payload);
+gc_collect_cycles();
+// The reference counter for $free_me is at -1 for PHP 7 right now.
+// Increment the reference counter by 1 -> rc is 0
+$a = $unserialized_payload[1];
+// Increment the reference counter by 1 again -> rc is 1
+$b = $a;
+// Trigger free of $free_me (referenced by $m[1]).
+unset($b);
+$fill_freed_space_1 = "filler_zval_1";
+$fill_freed_space_2 = "filler_zval_2";
+$fill_freed_space_3 = "filler_zval_3";
+$fill_freed_space_4 = "filler_zval_4";
+debug_zval_dump($unserialized_payload[1]);
+?>
+--EXPECTF--
+array(1) refcount(1){
+  [0]=>
+  object(stdClass)#%d (0) refcount(3){
+  }
+}

ext/zip/php_zip.c

@@ -1015,6 +1015,14 @@ static int php_zip_has_property(zval *object, zval *member, int type, const zend
 }
 /* }}} */
 
+static HashTable *php_zip_get_gc(zval *object, zval ***gc_data, int *gc_data_count TSRMLS_DC) /* {{{ */
+{
+	*gc_data = NULL;
+	*gc_data_count = 0;
+	return zend_std_get_properties(object TSRMLS_CC);
+}
+/* }}} */
+
 static HashTable *php_zip_get_properties(zval *object TSRMLS_DC)/* {{{ */
 {
 	ze_zip_object *obj;
@@ -2777,6 +2785,7 @@ static PHP_MINIT_FUNCTION(zip)
 	zip_object_handlers.clone_obj		= NULL;
 	zip_object_handlers.get_property_ptr_ptr = php_zip_get_property_ptr_ptr;
 
+	zip_object_handlers.get_gc          = php_zip_get_gc;
 	zip_object_handlers.get_properties = php_zip_get_properties;
 	zip_object_handlers.read_property	= php_zip_read_property;
 	zip_object_handlers.has_property	= php_zip_has_property;