motionpixels: Clip YUV values after applying a gradient.

Prevents illegal reads on truncated and malformed input.

CC: libav-stable@libav.org
(cherry picked from commit b5da848facd41169283d7bfe568b83bdfa7fc42e)

Signed-off-by: Reinhard Tartler <siretart@tauware.de>
(cherry picked from commit aaa6a666774eb02c351c84e80622a5c69e9b642e)

Signed-off-by: Reinhard Tartler <siretart@tauware.de>
(cherry picked from commit 50073e2395522b6e2b8698ff0dd06ffaf8cbf8ce)

Signed-off-by: Reinhard Tartler <siretart@tauware.de>
This commit is contained in:
Alex Converse 2012-05-02 12:08:03 -07:00 committed by Reinhard Tartler
parent 5933af562e
commit e9c9707316

View File

@ -188,10 +188,13 @@ static void mp_decode_line(MotionPixelsContext *mp, GetBitContext *gb, int y)
p = mp_get_yuv_from_rgb(mp, x - 1, y);
} else {
p.y += mp_gradient(mp, 0, mp_get_vlc(mp, gb));
p.y = av_clip(p.y, 0, 31);
if ((x & 3) == 0) {
if ((y & 3) == 0) {
p.v += mp_gradient(mp, 1, mp_get_vlc(mp, gb));
p.v = av_clip(p.v, -32, 31);
p.u += mp_gradient(mp, 2, mp_get_vlc(mp, gb));
p.u = av_clip(p.u, -32, 31);
mp->hpt[((y / 4) * mp->avctx->width + x) / 4] = p;
} else {
p.v = mp->hpt[((y / 4) * mp->avctx->width + x) / 4].v;
@ -215,9 +218,12 @@ static void mp_decode_frame_helper(MotionPixelsContext *mp, GetBitContext *gb)
p = mp_get_yuv_from_rgb(mp, 0, y);
} else {
p.y += mp_gradient(mp, 0, mp_get_vlc(mp, gb));
p.y = av_clip(p.y, 0, 31);
if ((y & 3) == 0) {
p.v += mp_gradient(mp, 1, mp_get_vlc(mp, gb));
p.v = av_clip(p.v, -32, 31);
p.u += mp_gradient(mp, 2, mp_get_vlc(mp, gb));
p.u = av_clip(p.u, -32, 31);
}
mp->vpt[y] = p;
mp_set_rgb_from_yuv(mp, 0, y, &p);