QMenu: guard for destruction when emitting action signals

If a slot connected to a QMenu-action destroys the QMenu, then
we must not touch data members in subsequent code, and instead return
immediately.

We cannot use QBoolBlocker here, as that would reset the data
member of QMenuPrivate even when trying to return early.

Fixes: QTBUG-106718
Pick-to: 6.5 6.4 6.2
Change-Id: I6b5ea471b1bf1f9864e1384382100f8f6c01346f
Reviewed-by: Axel Spoerl <axel.spoerl@qt.io>

2 files changed, 31 insertions, 3 deletions

diff --git a/src/widgets/widgets/qmenu.cpp b/src/widgets/widgets/qmenu.cpp
index 4e4c8ebe15..987dce71d9 100644
--- a/src/widgets/widgets/qmenu.cpp
+++ b/src/widgets/widgets/qmenu.cpp
@@ -1387,9 +1387,18 @@ bool QMenuPrivate::mouseEventTaken(QMouseEvent *e)
 void QMenuPrivate::activateCausedStack(const QList<QPointer<QWidget>> &causedStack, QAction *action,
                                        QAction::ActionEvent action_e, bool self)
 {
-    QBoolBlocker guard(activationRecursionGuard);
+    Q_Q(QMenu);
+    // can't use QBoolBlocker here
+    const bool activationRecursionGuardReset = activationRecursionGuard;
+    activationRecursionGuard = true;
+    QPointer<QMenu> guard(q);
     if (self)
         action->activate(action_e);
+    if (!guard)
+        return;
+    auto boolBlocker = qScopeGuard([this, activationRecursionGuardReset]{
+        activationRecursionGuard = activationRecursionGuardReset;
+    });
 
     for(int i = 0; i < causedStack.size(); ++i) {
         QPointer<QWidget> widget = causedStack.at(i);
@@ -1465,9 +1474,10 @@ void QMenuPrivate::activateAction(QAction *action, QAction::ActionEvent action_e
 #endif
     }
 
-
+    QPointer<QMenu> thisGuard(q);
     activateCausedStack(causedStack, action, action_e, self);
-
+    if (!thisGuard)
+        return;
 
     if (action_e == QAction::Hover) {
 #if QT_CONFIG(accessibility)
diff --git a/tests/auto/widgets/widgets/qmenu/tst_qmenu.cpp b/tests/auto/widgets/widgets/qmenu/tst_qmenu.cpp
index 1df16d783e..73cdbe87fe 100644
--- a/tests/auto/widgets/widgets/qmenu/tst_qmenu.cpp
+++ b/tests/auto/widgets/widgets/qmenu/tst_qmenu.cpp
@@ -112,6 +112,7 @@ private slots:
     void tearOffMenuNotDisplayed();
     void QTBUG_61039_menu_shortcuts();
     void screenOrientationChangedCloseMenu();
+    void deleteWhenTriggered();
 
 protected slots:
     void onActivated(QAction*);
@@ -2013,5 +2014,22 @@ void tst_QMenu::screenOrientationChangedCloseMenu()
      QTRY_COMPARE(menu.isVisible(),false);
 }
 
+/*
+    Verify that deleting the menu in a slot connected to an
+    action's triggered signal doesn't crash.
+    QTBUG-106718
+*/
+void tst_QMenu::deleteWhenTriggered()
+{
+    QPointer<QMenu> menu = new QMenu;
+    QAction *action = menu->addAction("Action", [&menu]{
+        delete menu;
+    });
+    menu->popup(QGuiApplication::primaryScreen()->availableGeometry().center());
+    menu->setActiveAction(action);
+    QTest::keyClick(menu, Qt::Key_Return);
+    QTRY_VERIFY(!menu);
+}
+
 QTEST_MAIN(tst_QMenu)
 #include "tst_qmenu.moc"