Deserializing a QVector from a QDataStream should be defensive

The QVector parsing done by QDataStream can be used by a remote process to a segmentation fault. High level: specifying a very large size of a very large type and that the QDataStream is not checked for atEnd. This can be improved in two ways: do not resize the QVector instead use append, secondly, check atEnd of s (the QDataStream).

I think this is really a critical vulnerability and should be addressed and back ported immediately.