From 7cdc61becd095b64a786b2625f321624e7111f3d Mon Sep 17 00:00:00 2001 From: Gerd Hoffmann Date: Fri, 9 Mar 2018 15:37:04 +0100 Subject: vga: fix region calculation Typically the scanline length and the line offset are identical. But in case they are not our calculation for region_end is incorrect. Using line_offset is fine for all scanlines, except the last one where we have to use the actual scanline length. Fixes: CVE-2018-7550 Reported-by: Ross Lagerwall Signed-off-by: Gerd Hoffmann Reviewed-by: Prasad J Pandit Tested-by: Ross Lagerwall Message-id: 20180309143704.13420-1-kraxel@redhat.com --- hw/display/vga.c | 2 ++ 1 file changed, 2 insertions(+) (limited to 'hw/display/vga.c') diff --git a/hw/display/vga.c b/hw/display/vga.c index 28f298b342..72181330b8 100644 --- a/hw/display/vga.c +++ b/hw/display/vga.c @@ -1483,6 +1483,8 @@ static void vga_draw_graphic(VGACommonState *s, int full_update) region_start = (s->start_addr * 4); region_end = region_start + (ram_addr_t)s->line_offset * height; + region_end += width * s->get_bpp(s) / 8; /* scanline length */ + region_end -= s->line_offset; if (region_end > s->vbe_size) { /* wraps around (can happen with cirrus vbe modes) */ region_start = 0; -- cgit v1.2.3-55-g7522