[FFmpeg-cvslog] avcodec/h264idct_template: Fix integer overflow in ff_h264_chroma422_dc_dequant_idct()

[Michael Niedermayer]

ffmpeg | branch: master | Michael Niedermayer <michael at niedermayer.cc> | Thu Nov  5 22:14:21 2020 +0100| [51dfd6f1bdb03bfc7574b12e921fb3b8639ba5cf] | committer: Michael Niedermayer

avcodec/h264idct_template: Fix integer overflow in ff_h264_chroma422_dc_dequant_idct()

Fixes: signed integer overflow: -2105540608 - 2105540608 cannot be represented in type 'int'
Fixes: 26870/clusterfuzz-testcase-minimized-ffmpeg_AV_CODEC_ID_H264_fuzzer-5656647567147008

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=51dfd6f1bdb03bfc7574b12e921fb3b8639ba5cf
---

 libavcodec/h264idct_template.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/libavcodec/h264idct_template.c b/libavcodec/h264idct_template.c
index f19579a47c..ce66ed3ab8 100644
--- a/libavcodec/h264idct_template.c
+++ b/libavcodec/h264idct_template.c
@@ -283,8 +283,8 @@ void FUNCC(ff_h264_chroma422_dc_dequant_idct)(int16_t *_block, int qmul){
     dctcoef *block = (dctcoef*)_block;
 
     for(i=0; i<4; i++){
-        temp[2*i+0] = block[stride*i + xStride*0] + block[stride*i + xStride*1];
-        temp[2*i+1] = block[stride*i + xStride*0] - block[stride*i + xStride*1];
+        temp[2*i+0] = block[stride*i + xStride*0] + (unsigned)block[stride*i + xStride*1];
+        temp[2*i+1] = block[stride*i + xStride*0] - (unsigned)block[stride*i + xStride*1];
     }
 
     for(i=0; i<2; i++){