Fix possible crash in the open62541 backend

QOpen62541Node::enableMonitoring() passes the node id member of the
node to the backend. If a string node id is used and the node is
deleted while or before enableMonitoring in the backend is running,
a crash occurs.
Passing a copy of the node id to the backend fixes the issue.

Change-Id: I0fca4150226c24182022afb95a72dab98f3d712a
Reviewed-by: Maurice Kalinowski <maurice.kalinowski@qt.io>
Reviewed-by: Frank Meerkoetter <frank.meerkoetter@basyskom.com>

2 files changed, 5 insertions, 1 deletions

diff --git a/src/plugins/opcua/open62541/qopen62541backend.cpp b/src/plugins/opcua/open62541/qopen62541backend.cpp
index 29fe8d6..24aedf8 100644
--- a/src/plugins/opcua/open62541/qopen62541backend.cpp
+++ b/src/plugins/opcua/open62541/qopen62541backend.cpp
@@ -238,6 +238,8 @@ void Open62541AsyncBackend::enableMonitoring(uintptr_t handle, UA_NodeId id, QOp
         }
     });
 
+    UA_NodeId_deleteMembers(&id);
+
     if (usedSubscription->monitoredItemsCount() == 0)
         removeSubscription(usedSubscription->subscriptionId()); // No items were added
 
diff --git a/src/plugins/opcua/open62541/qopen62541node.cpp b/src/plugins/opcua/open62541/qopen62541node.cpp
index 2b9166b..9285eba 100644
--- a/src/plugins/opcua/open62541/qopen62541node.cpp
+++ b/src/plugins/opcua/open62541/qopen62541node.cpp
@@ -76,10 +76,12 @@ bool QOpen62541Node::readAttributes(QOpcUa::NodeAttributes attr, const QString &
 
 bool QOpen62541Node::enableMonitoring(QOpcUa::NodeAttributes attr, const QOpcUaMonitoringParameters &settings)
 {
+    UA_NodeId tempId;
+    UA_NodeId_copy(&m_nodeId, &tempId);
     return QMetaObject::invokeMethod(m_client->m_backend, "enableMonitoring",
                                      Qt::QueuedConnection,
                                      Q_ARG(uintptr_t, reinterpret_cast<uintptr_t>(this)),
-                                     Q_ARG(UA_NodeId, m_nodeId),
+                                     Q_ARG(UA_NodeId, tempId),
                                      Q_ARG(QOpcUa::NodeAttributes, attr),
                                      Q_ARG(QOpcUaMonitoringParameters, settings));
 }