From 677ee0cf7cf492482b4dd4d96986b93f89cb69b3 Mon Sep 17 00:00:00 2001
From: David Redondo <qt@david-redondo.de>
Date: Wed, 9 Apr 2025 16:06:40 +0200
Subject: [PATCH] QGnomeTheme: Prevent leak of QDBusPendingCallWatcher

Otherwise the watcher can outlive the theme and the connected lambda
calls into the already destroyed theme.

Change-Id: I55e7834d1eb806d9f5f1945a4e1016d14b2969b6
Reviewed-by: Axel Spoerl <axel.spoerl@qt.io>
---
 src/gui/platform/unix/qgnometheme.cpp | 5 ++---
 src/gui/platform/unix/qgnometheme_p.h | 2 ++
 2 files changed, 4 insertions(+), 3 deletions(-)

diff --git a/src/gui/platform/unix/qgnometheme.cpp b/src/gui/platform/unix/qgnometheme.cpp
index c70c3580185..aafaff3732b 100644
--- a/src/gui/platform/unix/qgnometheme.cpp
+++ b/src/gui/platform/unix/qgnometheme.cpp
@@ -66,15 +66,14 @@ QGnomeThemePrivate::QGnomeThemePrivate()
 
         message.setArguments({});
         message << appearanceNamespace << contrastKey;
-        QDBusPendingCallWatcher *watcher = new QDBusPendingCallWatcher(dbus.asyncCall(message));
-        QObject::connect(watcher, &QDBusPendingCallWatcher::finished, watcher, [this](QDBusPendingCallWatcher *watcher) {
+        pendingCallWatcher = std::make_unique<QDBusPendingCallWatcher>(dbus.asyncCall(message));
+        QObject::connect(pendingCallWatcher.get(), &QDBusPendingCallWatcher::finished, pendingCallWatcher.get(), [this](QDBusPendingCallWatcher *watcher) {
             if (!watcher->isError()) {
                 QDBusPendingReply<QVariant> reply = *watcher;
                 if (Q_LIKELY(reply.isValid()))
                     updateHighContrast(static_cast<Qt::ContrastPreference>(reply.value().toUInt()));
             }
             initDbus();
-            watcher->deleteLater();
         });
     } else {
         qCWarning(lcQpaThemeGnome) << "dbus connection failed. Last error: " << dbus.lastError();
diff --git a/src/gui/platform/unix/qgnometheme_p.h b/src/gui/platform/unix/qgnometheme_p.h
index 08bba609875..41df765eccf 100644
--- a/src/gui/platform/unix/qgnometheme_p.h
+++ b/src/gui/platform/unix/qgnometheme_p.h
@@ -24,6 +24,7 @@ QT_BEGIN_NAMESPACE
 class QGnomeThemePrivate;
 #if QT_CONFIG(dbus)
 class QDBusListener;
+class QDBusPendingCallWatcher;
 #endif
 
 class Q_GUI_EXPORT QGnomeTheme : public QGenericUnixTheme
@@ -66,6 +67,7 @@ public:
     Qt::ContrastPreference m_contrast = Qt::ContrastPreference::NoPreference;
 private:
     std::unique_ptr<QDBusListener> dbus;
+    std::unique_ptr<QDBusPendingCallWatcher> pendingCallWatcher;
     bool initDbus();
     void updateColorScheme(const QString &themeName);
     void updateHighContrast(Qt::ContrastPreference contrast);