The code was incorrectly calculating the end address rather than the size of
the required region.

Signed-off-by: Mark Cave-Ayland <mark.cave-ayland@ilande.co.uk>
---
 hw/display/cg3.c |    2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/hw/display/cg3.c b/hw/display/cg3.c
index 7d43694..b42f60e 100644
--- a/hw/display/cg3.c
+++ b/hw/display/cg3.c
@@ -114,7 +114,7 @@ static void cg3_update_display(void *opaque)
         int update = s->full_update;
 
         page = y * width;
-        update |= memory_region_get_dirty(&s->vram_mem, page, page + width,
+        update |= memory_region_get_dirty(&s->vram_mem, page, width,
                                           DIRTY_MEMORY_VGA);
         if (update) {
             if (y_start < 0) {
-- 
1.7.10.4