[FFmpeg-cvslog] avcodec/scpr: Skip frames which change nothing

[Michael Niedermayer]

ffmpeg | branch: master | Michael Niedermayer <michael at niedermayer.cc> | Tue Sep 25 02:36:35 2018 +0200| [d702769213487923c0fb0abe4b61f4d9ebddb88b] | committer: Michael Niedermayer

avcodec/scpr: Skip frames which change nothing

Fixes: Timeout
Fixes: 10292/clusterfuzz-testcase-minimized-ffmpeg_AV_CODEC_ID_SCPR_fuzzer-5687943864254464

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=d702769213487923c0fb0abe4b61f4d9ebddb88b
---

 libavcodec/scpr.c | 4 +++-
 1 file changed, 3 insertions(+), 1 deletion(-)

diff --git a/libavcodec/scpr.c b/libavcodec/scpr.c
index 81597aa4dc..e41fbbec13 100644
--- a/libavcodec/scpr.c
+++ b/libavcodec/scpr.c
@@ -516,7 +516,7 @@ static int decompress_p(AVCodecContext *avctx,
     int backstep = linesize - avctx->width;
 
     if (bytestream2_get_byte(gb) == 0)
-        return 0;
+        return 1;
     bytestream2_skip(gb, 1);
     init_rangecoder(&s->rc, gb);
 
@@ -813,6 +813,8 @@ static int decode_frame(AVCodecContext *avctx, void *data, int *got_frame,
                            s->current_frame->linesize[0] / 4,
                            (uint32_t *)s->last_frame->data[0],
                            s->last_frame->linesize[0] / 4);
+        if (ret == 1)
+            return avpkt->size;
     } else {
         return AVERROR_PATCHWELCOME;
     }