cirrus: add blit_is_unsafe call to cirrus_bitblt_cputovideo (CVE-2017-2620)
CIRRUS_BLTMODE_MEMSYSSRC blits do NOT check blit destination
and blit width, at all. Oops. Fix it.
Security impact: high.
The missing blit destination check allows to write to host memory.
Basically same as CVE-2014-8106 for the other blit variants.
Cc: qemu-stable@nongnu.org
Signed-off-by: Gerd Hoffmann <kraxel@redhat.com>
(cherry picked from commit
92f2b88cea48c6aeba8de568a45f2ed958f3c298)
Signed-off-by: Michael Roth <mdroth@linux.vnet.ibm.com>