Avoid MAV after disconnecting due to protocol violationv5.12.55.12.5

closeConnection() clears m_readBuffer, so that
`m_readBuffer.constData() + m_readPosition` accesses a disposed memory

Change-Id: Ide4e4d8fdafe81181fceb9ebe2692aaa25ba8034
Reviewed-by: Maurice Kalinowski <maurice.kalinowski@qt.io>

1 files changed, 1 insertions, 0 deletions

diff --git a/src/mqtt/qmqttconnection.cpp b/src/mqtt/qmqttconnection.cpp
index e3beb56..f207da4 100644
--- a/src/mqtt/qmqttconnection.cpp
+++ b/src/mqtt/qmqttconnection.cpp
@@ -706,6 +706,7 @@ void QMqttConnection::readBuffer(char *data, quint64 size)
     if (Q_UNLIKELY(quint64(m_readBuffer.size() - m_readPosition) < size)) {
         qCDebug(lcMqttConnection) << "Reaching out of buffer, protocol violation";
         closeConnection(QMqttClient::ProtocolViolation);
+        return;
     }
     memcpy(data, m_readBuffer.constData() + m_readPosition, size);
     m_readPosition += size;