prepare: don't bother making another property info copy if it already exists

fo classes that were unlinked during first copy, we might've already copied the relevant property info
to the destination thread. In this case in the past, this would just silently fail to insert the updated
property info and go on to free it.

We probably ought to get rid of the old property_info and replace it with the newly copied version,
but for now this restores the original behaviour, which seemed to work anyway???

However, possible that this may break with property hooks inheritance. Needs further testing.

Author: dktapps

src/prepare.c

@@ -255,10 +255,15 @@ static void prepare_class_property_table(const pmmpthread_ident_t* source, zend_
 	zend_property_info *info;
 	zend_string *name;
 	ZEND_HASH_FOREACH_STR_KEY_PTR(&candidate->properties_info, name, info) {
-		zend_property_info* dup = copy_property_info(source, candidate, prepared, info);
-		if (!zend_hash_str_add_ptr(&prepared->properties_info, name->val, name->len, dup)) {
-			if (dup->doc_comment)
-				zend_string_release(dup->doc_comment);
+		zend_property_info* dup = zend_hash_find_ptr(&prepared->properties_info, name);
+		//TODO: if this is non-null it may need updating (if we copied it previously for an unlinked class)
+		//for now this just ensures that we don't have UAFs with reused property infos
+		//hopefully this doesn't shit a brick???
+		if (dup == NULL) {
+			dup = copy_property_info(source, candidate, prepared, info);
+			if (!zend_hash_str_add_ptr(&prepared->properties_info, name->val, name->len, dup)) {
+				ZEND_ASSERT(0);
+			}
 		}
 	} ZEND_HASH_FOREACH_END();