CNA-BUG-091: GameWindow keeps a raw pointer to the platform window owned by the Game's GraphicsDevice, and nothing clears it when the game disposes that device

CNA snapshot 009d40f5  ·  Known Issues › Current bugs  ·  source links pinned to 009d40f5

Game's constructor hands GraphicsDevice_.GetPlatformWindowInternal() to Window_.setWindowInternal; GraphicsDevice::Dispose destroys the platform window (destroyNativeResources resets platformWindow_), after which GameWindow members dereference freed memory.

Identifier

CNA-BUG-091

Category

Bug

Subsystem

Core & runtime

Status

Open

Verified against

CNA 009d40f5 (009d40f5dd085c4e674d3479675fac84b12b3e0a)

Severity

Low (a triage suggestion, not a project priority)

Evidence basis

Source-verified: read at TARGET, not executed

Tests touching this area

None

Affected contract

Microsoft::Xna::Framework::GameWindow members after an explicit GraphicsDevice::Dispose() on the Game's device

Expected behaviour

A borrowed pointer must not outlive its owner; either GameWindow should be detached when the device destroys its window, or the device must not destroy a window the Game still exposes.

Actual behaviour at TARGET

In Game.cpp the constructor calls Window_.setWindowInternal(GraphicsDevice_.GetPlatformWindowInternal(), ...). GameWindow.cpp stores it in window_ and uses it for Title, AllowUserResizing, IsBorderless, ClientBounds, Handle and the rest. GraphicsDevice.cpp's destroyNativeResources (called by Dispose) resets the owning std::unique_ptr<IPlatformWindow>. Nothing rebinds or clears GameWindow::window_, so after a game disposes its device (the manager comments note "A game may explicitly dispose its device from Draw()") the next Window property call touches freed memory.

Source locations

• modules/runtime/src/Game.cpp — Game constructor: Window_.setWindowInternal(...)
• modules/runtime/src/GameWindow.cpp — GameWindow::setWindowInternal and the window_ users
• modules/graphics/src/Xna/GraphicsDevice.cpp — GraphicsDevice::destroyNativeResources (platformWindow_.reset())

Evidence

Checked by reading the named sources at 009d40f5; nothing was built or executed for this entry. The GraphicsDeviceManager guards its own frame lease against this (its Disposing handler); GameWindow has no equivalent.

Focused reproduction

// Illustrative; not compiled or run for this entry.
protected: void Draw(const GameTime& t) override {
    getGraphicsDeviceProperty().Dispose();   // explicit device disposal
    Exit();
}
// later in the same run: getWindowProperty().setTitleProperty("...") or ClientBounds -> freed IPlatformWindow

Current tests

No test disposes the Game's device and then uses the window.

Regression test

An ASan test that disposes the Game's GraphicsDevice and then reads Window.ClientBounds (expecting a defined result or an ObjectDisposedException).

Blast radius

Games that explicitly dispose their GraphicsDevice before the Game ends; the normal shutdown order is unaffected.

Workaround

Do not dispose the Game's GraphicsDevice yourself; let the Game own it.