Fix some QtDBus crashes during application destruction

It's possible that some code executes after QDBusConnectionManager is
destroyed and still tries to access QtDBus. Protect against such
crashes.

Change-Id: I87e17314d8b24ae983b1fffd1453c13fbd3cf48e
Reviewed-by: René J.V. Bertin <rjvbertin@gmail.com>
Reviewed-by: Alex Blasche <alexander.blasche@qt.io>
Reviewed-by: Oswald Buddenhagen <oswald.buddenhagen@qt.io>

1 files changed, 8 insertions, 4 deletions

diff --git a/src/dbus/qdbusconnection.cpp b/src/dbus/qdbusconnection.cpp
index c869707d6d..8fae11c8cd 100644
--- a/src/dbus/qdbusconnection.cpp
+++ b/src/dbus/qdbusconnection.cpp
@@ -426,7 +426,7 @@ void QDBusConnectionManager::createServer(const QString &address, void *server)
 */
 QDBusConnection::QDBusConnection(const QString &name)
 {
-    if (name.isEmpty()) {
+    if (name.isEmpty() || _q_manager.isDestroyed()) {
         d = 0;
     } else {
         QMutexLocker locker(&_q_manager()->mutex);
@@ -491,7 +491,7 @@ QDBusConnection &QDBusConnection::operator=(const QDBusConnection &other)
 */
 QDBusConnection QDBusConnection::connectToBus(BusType type, const QString &name)
 {
-    if (!qdbus_loadLibDBus()) {
+    if (_q_manager.isDestroyed() || !qdbus_loadLibDBus()) {
         QDBusConnectionPrivate *d = 0;
         return QDBusConnection(d);
     }
@@ -505,7 +505,7 @@ QDBusConnection QDBusConnection::connectToBus(BusType type, const QString &name)
 QDBusConnection QDBusConnection::connectToBus(const QString &address,
                                               const QString &name)
 {
-    if (!qdbus_loadLibDBus()) {
+    if (_q_manager.isDestroyed() || !qdbus_loadLibDBus()) {
         QDBusConnectionPrivate *d = 0;
         return QDBusConnection(d);
     }
@@ -520,7 +520,7 @@ QDBusConnection QDBusConnection::connectToBus(const QString &address,
 QDBusConnection QDBusConnection::connectToPeer(const QString &address,
                                                const QString &name)
 {
-    if (!qdbus_loadLibDBus()) {
+    if (_q_manager.isDestroyed() || !qdbus_loadLibDBus()) {
         QDBusConnectionPrivate *d = 0;
         return QDBusConnection(d);
     }
@@ -1175,6 +1175,8 @@ bool QDBusConnection::unregisterService(const QString &serviceName)
 */
 QDBusConnection QDBusConnection::sessionBus()
 {
+    if (_q_manager.isDestroyed())
+        return QDBusConnection(Q_NULLPTR);
     return QDBusConnection(_q_manager()->busConnection(SessionBus));
 }
 
@@ -1187,6 +1189,8 @@ QDBusConnection QDBusConnection::sessionBus()
 */
 QDBusConnection QDBusConnection::systemBus()
 {
+    if (_q_manager.isDestroyed())
+        return QDBusConnection(Q_NULLPTR);
     return QDBusConnection(_q_manager()->busConnection(SystemBus));
 }