[FFmpeg-cvslog] avcodec/cdgraphics: limit scrolling to the line

[Michael Niedermayer]

ffmpeg | branch: master | Michael Niedermayer <michael at niedermayer.cc> | Thu Jun  9 22:36:00 2022 +0200| [b7e30a13d4e4557b87f977b76a6bb5e3cbe5ac78] | committer: Michael Niedermayer

avcodec/cdgraphics: limit scrolling to the line

Fixes: out of array access
Fixes: 47877/clusterfuzz-testcase-minimized-ffmpeg_AV_CODEC_ID_CDGRAPHICS_fuzzer-5690504626438144

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

> http://git.videolan.org/gitweb.cgi/ffmpeg.git/?a=commit;h=b7e30a13d4e4557b87f977b76a6bb5e3cbe5ac78
---

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

diff --git a/libavcodec/cdgraphics.c b/libavcodec/cdgraphics.c
index b851ec430b..73654019e6 100644
--- a/libavcodec/cdgraphics.c
+++ b/libavcodec/cdgraphics.c
@@ -240,7 +240,7 @@ static void cdg_scroll(CDGraphicsContext *cc, uint8_t *data,
     for (y = FFMAX(0, vinc); y < FFMIN(CDG_FULL_HEIGHT + vinc, CDG_FULL_HEIGHT); y++)
         memcpy(out + FFMAX(0, hinc) + stride * y,
                in + FFMAX(0, hinc) - hinc + (y - vinc) * stride,
-               FFMIN(stride + hinc, stride));
+               FFABS(stride) - FFABS(hinc));
 
     if (vinc > 0)
         cdg_fill_wrapper(0, 0, out,