Qemu: display: cirrus: potential arbitrary code execution via cirrus_bitblt_cputovideo

Quick emulator QEMU built with the Cirrus CLGD 54xx VGA Emulator support is vulnerable to an out-of-bounds access issue. The issue could occur while copying VGA data in cirrusbitbltcputovideo. A privileged user inside guest could use this flaw to crash the QEMU process OR potentially execute...