[libav-devel] [PATCH] motionpixels: Clip YUV values after applying a gradient.

Alex Converse alex.converse at gmail.com
Wed May 2 21:11:43 CEST 2012


Prevents illegal reads on truncated and malformed input.
---
 libavcodec/motionpixels.c |    6 ++++++
 1 files changed, 6 insertions(+), 0 deletions(-)

diff --git a/libavcodec/motionpixels.c b/libavcodec/motionpixels.c
index 6151e6a..8a3c870 100644
--- a/libavcodec/motionpixels.c
+++ b/libavcodec/motionpixels.c
@@ -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);
-- 
1.7.7.3



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