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motionpixels: Clip YUV values after applying a gradient.

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Prevents illegal reads on truncated and malformed input.

CC: libav-stable@libav.org
This commit is contained in:
Alex Converse 2012-05-02 12:08:03 -07:00
parent 5eec5a79da
commit b5da848fac
1 changed files with 6 additions and 0 deletions
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6
libavcodec/motionpixels.c
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@ -190,10 +190,13 @@ 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;
@ -217,9 +220,12 @@ 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);