[FFmpeg-cvslog] avcodec/apedec: Fix integer overflow in predictor_update_3930()

[Michael Niedermayer]

ffmpeg | branch: master | Michael Niedermayer <michael at niedermayer.cc> | Fri Sep 27 17:19:36 2019 +0200| [5c072c9ed7c6f173b8a0a886fb7fe1e8e4c1fadd] | committer: Michael Niedermayer

avcodec/apedec: Fix integer overflow in predictor_update_3930()

Fixes: signed integer overflow: -69555262 * 31 cannot be represented in type 'int'
Fixes: 17698/clusterfuzz-testcase-minimized-ffmpeg_AV_CODEC_ID_APE_fuzzer-5728970447781888

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=5c072c9ed7c6f173b8a0a886fb7fe1e8e4c1fadd
---

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

diff --git a/libavcodec/apedec.c b/libavcodec/apedec.c
index c6754a5ee6..75c6a96437 100644
--- a/libavcodec/apedec.c
+++ b/libavcodec/apedec.c
@@ -1055,7 +1055,7 @@ static av_always_inline int predictor_update_3930(APEPredictor *p,
                   d3 * p->coeffsA[filter][3];
 
     p->lastA[filter] = decoded + (predictionA >> 9);
-    p->filterA[filter] = p->lastA[filter] + ((p->filterA[filter] * 31) >> 5);
+    p->filterA[filter] = p->lastA[filter] + ((int)(p->filterA[filter] * 31U) >> 5);
 
     sign = APESIGN(decoded);
     p->coeffsA[filter][0] += ((d0 < 0) * 2 - 1) * sign;