fix: make FString a local lua param

This fixes some issues related to FString lifetime causing it to become garbage data, FString should be stored by value instead. Credits: @Yangff
UE4SS-RE · Mar 7, 2024 · 21b1717 · 21b1717
1 parent 79e017c
commit 21b1717
Show file tree

Hide file tree

Showing 4 changed files with 10 additions and 8 deletions.
diff --git a/UE4SS/include/LuaType/LuaFString.hpp b/UE4SS/include/LuaType/LuaFString.hpp
@@ -16,7 +16,7 @@ namespace RC::LuaType
             return "FString";
         }
     };
-    class FString : public RemoteObjectBase<Unreal::FString, FStringName>
+    class FString : public LocalObjectBase<Unreal::FString, FStringName>
     {
       private:
         explicit FString(Unreal::FString* object);

diff --git a/UE4SS/src/LuaType/LuaFString.cpp b/UE4SS/src/LuaType/LuaFString.cpp
@@ -6,7 +6,7 @@
 
 namespace RC::LuaType
 {
-    FString::FString(Unreal::FString* object) : RemoteObjectBase<Unreal::FString, FStringName>(object)
+    FString::FString(Unreal::FString* object) : LocalObjectBase<Unreal::FString, FStringName>(std::move(Unreal::FString(*object)))
     {
     }
 
@@ -20,7 +20,7 @@ namespace RC::LuaType
         if (lua.is_nil(-1))
         {
             lua.discard_value(-1);
-            LuaMadeSimple::Type::RemoteObject<Unreal::FString>::construct(lua, lua_object);
+            lua.prepare_new_table();
             setup_metamethods(lua_object);
             setup_member_functions<LuaMadeSimple::Type::IsFinal::Yes>(table);
             lua.new_metatable<LuaType::FString>(metatable_name, lua_object.get_metamethods());
@@ -52,9 +52,9 @@ namespace RC::LuaType
     auto FString::setup_member_functions(const LuaMadeSimple::Lua::Table& table) -> void
     {
         table.add_pair("ToString", [](const LuaMadeSimple::Lua& lua) -> int {
-            const auto& lua_object = lua.get_userdata<LuaType::FString>();
+            auto& lua_object = lua.get_userdata<LuaType::FString>();
 
-            const wchar_t* string_data = lua_object.get_remote_cpp_object()->GetCharArray();
+            const wchar_t* string_data = lua_object.get_local_cpp_object().GetCharArray();
             if (string_data)
             {
                 lua.set_string(to_string(string_data));
@@ -68,9 +68,9 @@ namespace RC::LuaType
         });
 
         table.add_pair("Clear", [](const LuaMadeSimple::Lua& lua) -> int {
-            const auto& lua_object = lua.get_userdata<LuaType::FString>();
+            auto& lua_object = lua.get_userdata<LuaType::FString>();
 
-            lua_object.get_remote_cpp_object()->Clear();
+            lua_object.get_local_cpp_object().Clear();
 
             return 0;
         });

diff --git a/UE4SS/src/LuaType/LuaUObject.cpp b/UE4SS/src/LuaType/LuaUObject.cpp
@@ -1112,7 +1112,7 @@ namespace RC::LuaType
             else if (params.lua.is_userdata())
             {
                 auto& rhs = params.lua.get_userdata<LuaType::FString>();
-                string->SetCharArray(rhs.get_remote_cpp_object()->GetCharTArray());
+                string->SetCharArray(rhs.get_local_cpp_object().GetCharTArray());
             }
             else
             {

diff --git a/assets/Changelog.md b/assets/Changelog.md
@@ -43,6 +43,8 @@ Fixed BPModLoaderMod giving "bad conversion" errors.
 ### UHT Dumper
 
 ### Lua API
+Fixed FString use after free.
+
 Fixed the "IterateGameDirectories" global function throwing "bad conversion" errors.
 
 Fixed `FText` not working as a parameter (in `RegisterHook`, etc.).