libvirt: qemu: out-of-bounds read access in qemuDomainGetBlockIoTune() due to invalid index

An out-of-bounds read flaw was found in the way libvirt's qemuDomainGetBlockIoTune function looked up the disk index in a non-persistent live disk configuration while a persistent disk configuration was being indexed. A remote attacker able to establish a read-only connection to libvirtd could us...