qxl-render: add more sanity checks

Damn, the dirty rectangle values are signed integers.  So the checks
added by commit 788fbf042fc6d5aaeab56757e6dad622ac5f0c21 are not good
enough, we also have to make sure they are not negative.

[ Note: There must be something broken in spice-server so we get
  negative values in the first place.  Bug opened:
  https://bugzilla.redhat.com/show_bug.cgi?id=1135372 ]

Cc: qemu-stable@nongnu.org
Signed-off-by: Gerd Hoffmann <kraxel@redhat.com>
Reviewed-by: Dr. David Alan Gilbert <dgilbert@redhat.com>

diff --git a/hw/display/qxl-render.c b/hw/display/qxl-render.c
index cc2c2b1dbc5e75e4bd3e278dc4b3ff59aba9a788..bcc5c3701a404e95420e3ddf67a9cb2972fcd31e 100644 (file)
--- a/hw/display/qxl-render.c
+++ b/hw/display/qxl-render.c
@@ -138,7 +138,9 @@ static void qxl_render_update_area_unlocked(PCIQXLDevice *qxl)
         if (qemu_spice_rect_is_empty(qxl->dirty+i)) {
             break;
         }
-        if (qxl->dirty[i].left > qxl->dirty[i].right ||
+        if (qxl->dirty[i].left < 0 ||
+            qxl->dirty[i].top < 0 ||
+            qxl->dirty[i].left > qxl->dirty[i].right ||
             qxl->dirty[i].top > qxl->dirty[i].bottom ||
             qxl->dirty[i].right > qxl->guest_primary.surface.width ||
             qxl->dirty[i].bottom > qxl->guest_primary.surface.height) {