Fix null pointer access in QQuickOpenGLShaderEffectMaterialCache

If a QQuickWindow is destroyed without ever being rendered, then there won't be
any QOpenGLContext in QQuickOpenGLShaderEffectMaterial::cleanupMaterialCache.

Same goes for QQuickWidgetRenderControl.

Fixes: QTBUG-65236
Change-Id: I2742505d147bc8444b46688170d33fbb2844f2ac
Reviewed-by: Laszlo Agocs <laszlo.agocs@qt.io>

3 files changed, 5 insertions, 2 deletions

diff --git a/src/quick/items/qquickopenglshadereffectnode.cpp b/src/quick/items/qquickopenglshadereffectnode.cpp
index d51419a275..f32b32491b 100644
--- a/src/quick/items/qquickopenglshadereffectnode.cpp
+++ b/src/quick/items/qquickopenglshadereffectnode.cpp
@@ -366,6 +366,7 @@ class QQuickOpenGLShaderEffectMaterialCache : public QObject
 public:
     static QQuickOpenGLShaderEffectMaterialCache *get(bool create = true) {
         QOpenGLContext *ctx = QOpenGLContext::currentContext();
+        Q_ASSERT(ctx);
         QQuickOpenGLShaderEffectMaterialCache *me = ctx->findChild<QQuickOpenGLShaderEffectMaterialCache *>(QStringLiteral("__qt_ShaderEffectCache"), Qt::FindDirectChildrenOnly);
         if (!me && create) {
             me = new QQuickOpenGLShaderEffectMaterialCache();
diff --git a/src/quick/items/qquickrendercontrol.cpp b/src/quick/items/qquickrendercontrol.cpp
index 025acefec2..f6d4e7ed49 100644
--- a/src/quick/items/qquickrendercontrol.cpp
+++ b/src/quick/items/qquickrendercontrol.cpp
@@ -192,7 +192,8 @@ void QQuickRenderControlPrivate::windowDestroyed()
         QQuickWindowPrivate::get(window)->animationController = nullptr;
 
 #if QT_CONFIG(quick_shadereffect) && QT_CONFIG(opengl)
-        QQuickOpenGLShaderEffectMaterial::cleanupMaterialCache();
+        if (QOpenGLContext::currentContext())
+            QQuickOpenGLShaderEffectMaterial::cleanupMaterialCache();
 #endif
 
         window = nullptr;
diff --git a/src/quick/scenegraph/qsgrenderloop.cpp b/src/quick/scenegraph/qsgrenderloop.cpp
index 3d579fde46..2e91bafa7c 100644
--- a/src/quick/scenegraph/qsgrenderloop.cpp
+++ b/src/quick/scenegraph/qsgrenderloop.cpp
@@ -334,7 +334,8 @@ void QSGGuiThreadRenderLoop::windowDestroyed(QQuickWindow *window)
         qCDebug(QSG_LOG_RENDERLOOP, "cleanup without an OpenGL context");
 
 #if QT_CONFIG(quick_shadereffect) && QT_CONFIG(opengl)
-    QQuickOpenGLShaderEffectMaterial::cleanupMaterialCache();
+    if (current)
+        QQuickOpenGLShaderEffectMaterial::cleanupMaterialCache();
 #endif
 
     d->cleanupNodesOnShutdown();