On 3/12/2018 5:59 AM, Gerd Hoffmann wrote:
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

This doesn't appear to be the correct CVE number.

https://nvd.nist.gov/vuln/detail/CVE-2018-7550

..please confirm..

Thanks,

-Mark

Reported-by: Ross Lagerwall <ross.lagerw...@citrix.com>
Signed-off-by: Gerd Hoffmann <kra...@redhat.com>
Reviewed-by: Prasad J Pandit <p...@fedoraproject.org>
Tested-by: Ross Lagerwall <ross.lagerw...@citrix.com>
Message-id: 20180309143704.13420-1-kra...@redhat.com
---
  hw/display/vga.c | 2 ++
  1 file changed, 2 insertions(+)

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;


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