Don't crash: Connections with a signal on a nonexistent object

Task-number: QTBUG-56551
Change-Id: Ide09f177d3f6a3e9902f8ea904b3e6e4b998bd39
Reviewed-by: Jan Arve Sæther <jan-arve.saether@qt.io>

1 files changed, 4 insertions, 1 deletions

diff --git a/src/qml/qml/qqmlpropertycache.cpp b/src/qml/qml/qqmlpropertycache.cpp
index 88ce2fa1b9..d18159841c 100644
--- a/src/qml/qml/qqmlpropertycache.cpp
+++ b/src/qml/qml/qqmlpropertycache.cpp
@@ -970,8 +970,11 @@ int QQmlPropertyCache::originalClone(QObject *object, int index)
     QQmlData *data = QQmlData::get(object, false);
     if (data && data->propertyCache) {
         QQmlPropertyCache *cache = data->propertyCache;
-        while (cache->signal(index)->isCloned())
+        QQmlPropertyData *sig = cache->signal(index);
+        while (sig && sig->isCloned()) {
             --index;
+            sig = cache->signal(index);
+        }
     } else {
         while (QMetaObjectPrivate::signal(object->metaObject(), index).attributes() & QMetaMethod::Cloned)
             --index;