[FFmpeg-cvslog] avcodec/xan: Improve overlapping check

[Michael Niedermayer]

ffmpeg | branch: release/2.8 | Michael Niedermayer <michael at niedermayer.cc> | Mon Oct 30 23:21:40 2017 +0100| [35c1e95b41e9a626be39629993eb23dae2f80fd7] | committer: Michael Niedermayer

avcodec/xan: Improve overlapping check

Fixes: memcpy-param-overlap
Fixes: 3612/clusterfuzz-testcase-minimized-6393461273001984

Found-by: continuous fuzzing process https://github.com/google/oss-fuzz/tree/master/projects/ffmpeg
Signed-off-by: Michael Niedermayer <michael at niedermayer.cc>
(cherry picked from commit e8fafef1db43ead4eae5a6301ccc300e73aa47da)
Signed-off-by: Michael Niedermayer <michael at niedermayer.cc>

> http://git.videolan.org/gitweb.cgi/ffmpeg.git/?a=commit;h=35c1e95b41e9a626be39629993eb23dae2f80fd7
---

 libavcodec/xan.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/libavcodec/xan.c b/libavcodec/xan.c
index 662386af9a..85fa8e7394 100644
--- a/libavcodec/xan.c
+++ b/libavcodec/xan.c
@@ -262,7 +262,7 @@ static inline void xan_wc3_copy_pixel_run(XanContext *s, AVFrame *frame,
     prevframe_index = (y + motion_y) * stride + x + motion_x;
     prevframe_x = x + motion_x;
 
-    if (prev_palette_plane == palette_plane && FFABS(curframe_index - prevframe_index) < pixel_count) {
+    if (prev_palette_plane == palette_plane && FFABS(motion_x + width*motion_y) < pixel_count) {
          avpriv_request_sample(s->avctx, "Overlapping copy");
          return ;
     }