Izik Eidus found a bug in QEMU that allows priviledged guest user
to touch arbitrary memory in the hosting QEMU process. The bug is in
QXL/libspice code. Guest and host share region of memory and
use it to communicate with each other. Malicious user can use the
lack of validation of pointers embedded into data structures in
this memory area to touch host's abitrary memory location and/or make
the hosting QEMU process crash by dereferencing invalid pointer.