[FFmpeg-cvslog] avcodec/apedec: Fix integer overflow in filter_3800()

[Michael Niedermayer]

ffmpeg | branch: release/4.1 | Michael Niedermayer <michael at niedermayer.cc> | Sun Sep 11 00:30:42 2022 +0200| [a101c977826985adcc478d1f2f6f686679805826] | committer: Michael Niedermayer

avcodec/apedec: Fix integer overflow in filter_3800()

Fixes: signed integer overflow: -2147448926 + -198321 cannot be represented in type 'int'
Fixes: 48798/clusterfuzz-testcase-minimized-ffmpeg_AV_CODEC_ID_APE_fuzzer-5739619273015296
Fixes: 48798/clusterfuzz-testcase-minimized-ffmpeg_AV_CODEC_ID_APE_fuzzer-6744428485672960

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 f05247f6a4698c14f1cd523daa90188f50dcf6ad)
Signed-off-by: Michael Niedermayer <michael at niedermayer.cc>

> http://git.videolan.org/gitweb.cgi/ffmpeg.git/?a=commit;h=a101c977826985adcc478d1f2f6f686679805826
---

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

diff --git a/libavcodec/apedec.c b/libavcodec/apedec.c
index 035fa9a434..5a769a3ea9 100644
--- a/libavcodec/apedec.c
+++ b/libavcodec/apedec.c
@@ -880,7 +880,7 @@ static av_always_inline int filter_3800(APEPredictor *p,
     p->coeffsB[filter][0] += (((d3 >> 29) & 4) - 2) * sign;
     p->coeffsB[filter][1] -= (((d4 >> 30) & 2) - 1) * sign;
 
-    p->filterB[filter] = p->lastA[filter] + (predictionB >> shift);
+    p->filterB[filter] = p->lastA[filter] + (unsigned)(predictionB >> shift);
     p->filterA[filter] = p->filterB[filter] + (unsigned)((int)(p->filterA[filter] * 31U) >> 5);
 
     return p->filterA[filter];