cirrus: don't overflow CirrusVGAState->cirrus_bltbuf

This is CVE-2014-8106.

Signed-off-by: Gerd Hoffmann <kraxel@redhat.com>

diff --git a/hw/display/cirrus_vga.c b/hw/display/cirrus_vga.c
index 757ab633b21e4974eb4d0ebfcdfa10cbeae577f1..1a66fcf91d087c3b9517424433e03139ef6e857b 100644 (file)
--- a/hw/display/cirrus_vga.c
+++ b/hw/display/cirrus_vga.c
@@ -292,6 +292,10 @@ static bool blit_is_unsafe(struct CirrusVGAState *s)
     assert(s->cirrus_blt_width > 0);
     assert(s->cirrus_blt_height > 0);
 
+    if (s->cirrus_blt_width > CIRRUS_BLTBUFSIZE) {
+        return true;
+    }
+
     if (blit_region_is_unsafe(s, s->cirrus_blt_dstpitch,
                               s->cirrus_blt_dstaddr & s->cirrus_addr_mask)) {
         return true;