QEMU: virtio-net: stack buffer overflow in virtio_net_flush_tx()

A stack based buffer overflow was found in the virtio-net device of QEMU. This issue occurs when flushing TX in the virtionetflushtx function if guest features VIRTIONETFHASHREPORT, VIRTIOFVERSION1 and VIRTIONETFMRGRXBUF are enabled. This could allow a malicious user to overwrite local variables...