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View File 0080-vga-fix-region-calculation.patch of Package qemu (Project home:lucidd:branches:Virtualization)

From e5bdf248c24feab41fc7b8245e37277f1ae60e3e Mon Sep 17 00:00:00 2001
From: Gerd Hoffmann <kraxel@redhat.com>
Date: Fri, 9 Mar 2018 15:37:04 +0100
Subject: [PATCH] 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-2018-7858
Reported-by: Ross Lagerwall <ross.lagerwall@citrix.com>
Signed-off-by: Gerd Hoffmann <kraxel@redhat.com>
Reviewed-by: Prasad J Pandit <pjp@fedoraproject.org>
Tested-by: Ross Lagerwall <ross.lagerwall@citrix.com>
Message-id: 20180309143704.13420-1-kraxel@redhat.com
(cherry picked from commit 7cdc61becd095b64a786b2625f321624e7111f3d)
[BR: BSC#1084604 CVE-2018-7858 (NOTE: Above CVE reference was modified
by me, because it was incorrect)]
Signed-off-by: Bruce Rogers <brogers@suse.com>
---
 hw/display/vga.c | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/hw/display/vga.c b/hw/display/vga.c
index d150a3a3eb..1fa66d597d 100644
--- a/hw/display/vga.c
+++ b/hw/display/vga.c
@@ -1489,6 +1489,8 @@ 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;