Re: [Qemu-devel] [PULL 1/1] vga: fix region calculation

[Mark Kanda]

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 <address@hidden>
> Signed-off-by: Gerd Hoffmann <address@hidden>
> Reviewed-by: Prasad J Pandit <address@hidden>
> Tested-by: Ross Lagerwall <address@hidden>
> Message-id: address@hidden
> ---
>   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;