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From a4a396ff1f6bf512d8a1e65f692242d4332c615c Mon Sep 17 00:00:00 2001
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From: Gerd Hoffmann <kraxel@redhat.com>
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Date: Mon, 19 Mar 2018 14:34:59 +0100
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Subject: [PATCH 4/4] vga: fix region calculation
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RH-Author: Gerd Hoffmann <kraxel@redhat.com>
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Message-id: <20180319143459.15364-3-kraxel@redhat.com>
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Patchwork-id: 79360
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O-Subject: [RHV7.5 qemu-kvm-rhev PATCH 2/2] vga: fix region calculation
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Bugzilla: 1566878
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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: Laszlo Ersek <lersek@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 b6a3b95..f060f26 100644
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--- a/hw/display/vga.c
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+++ b/hw/display/vga.c
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@@ -1489,6 +1489,8 @@ 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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