QQuickShaderEffect: fix crash when hiding parent

It's possible for itemChange to be called during destruction when
deleting the QQuickShaderEffectImpl. We nullify m_impl before deleting
it via another pointer to it, so we must check that it's not null
before trying to use it.

Pick-to: 5.15
Fixes: QTBUG-86402
Change-Id: If4955445f7cc0d1f376bc9b86b95e1cca4d88ede
Reviewed-by: Laszlo Agocs <laszlo.agocs@qt.io>

1 files changed, 5 insertions, 1 deletions

diff --git a/src/quick/items/qquickshadereffect.cpp b/src/quick/items/qquickshadereffect.cpp
index 1e0e6c60b8..3ae342b475 100644
--- a/src/quick/items/qquickshadereffect.cpp
+++ b/src/quick/items/qquickshadereffect.cpp
@@ -735,7 +735,11 @@ void QQuickShaderEffect::componentComplete()
 
 void QQuickShaderEffect::itemChange(ItemChange change, const ItemChangeData &value)
 {
-    m_impl->handleItemChange(change, value);
+    // It's possible for itemChange to be called during destruction when deleting
+    // the QQuickShaderEffectImpl. We nullify m_impl before deleting it via another pointer
+    // to it, so we must check that it's not null before trying to use it here.
+    if (m_impl)
+        m_impl->handleItemChange(change, value);
     QQuickItem::itemChange(change, value);
 }