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From 3ed3904f7411bd5896aebdfcc6fe202dbfc2eef6 Mon Sep 17 00:00:00 2001
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From: Gerd Hoffmann <kraxel@redhat.com>
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Date: Mon, 9 Apr 2018 13:27:36 +0200
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Subject: [PATCH 2/2] vga: fix region calculation
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RH-Author: Gerd Hoffmann <kraxel@redhat.com>
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Message-id: <20180409132736.24598-3-kraxel@redhat.com>
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Patchwork-id: 79512
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O-Subject: [RHEL-7.5 qemu-kvm PATCH 2/2] vga: fix region calculation
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Bugzilla: 1567913
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RH-Acked-by: Dr. David Alan Gilbert <dgilbert@redhat.com>
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RH-Acked-by: Stefan Hajnoczi <stefanha@redhat.com>
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RH-Acked-by: John Snow <jsnow@redhat.com>
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Typically the scanline length and the line offset are identical.  But
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in case they are not our calculation for region_end is incorrect.  Using
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line_offset is fine for all scanlines, except the last one where we have
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to use the actual scanline length.
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Fixes: CVE-2018-7550
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Reported-by: Ross Lagerwall <ross.lagerwall@citrix.com>
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Signed-off-by: Gerd Hoffmann <kraxel@redhat.com>
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Reviewed-by: Prasad J Pandit <pjp@fedoraproject.org>
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Tested-by: Ross Lagerwall <ross.lagerwall@citrix.com>
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Message-id: 20180309143704.13420-1-kraxel@redhat.com
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(cherry picked from commit 7cdc61becd095b64a786b2625f321624e7111f3d)
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Signed-off-by: Miroslav Rezanina <mrezanin@redhat.com>
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---
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 hw/display/vga.c | 2 ++
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 1 file changed, 2 insertions(+)
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diff --git a/hw/display/vga.c b/hw/display/vga.c
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index 8e6c6d6..9270a75 100644
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--- a/hw/display/vga.c
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+++ b/hw/display/vga.c
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@@ -1535,6 +1535,8 @@ static void vga_draw_graphic(VGACommonState *s, int full_update)
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     region_start = (s->start_addr * 4);
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     region_end = region_start + (ram_addr_t)s->line_offset * height;
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+    region_end += width * s->get_bpp(s) / 8; /* scanline length */
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+    region_end -= s->line_offset;
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     if (region_end > s->vbe_size) {
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         /* wraps around (can happen with cirrus vbe modes) */
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         region_start = 0;
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-- 
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1.8.3.1
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