[FFmpeg-cvslog] avcodec/xvididct: Fix integer overflow in idct_row()

[Michael Niedermayer]

ffmpeg | branch: release/5.1 | Michael Niedermayer <michael at niedermayer.cc> | Fri Sep  8 00:13:11 2023 +0200| [d5f1ecbe247d3d75ea0474556bffab017c9054d6] | committer: Michael Niedermayer

avcodec/xvididct: Fix integer overflow in idct_row()

Fixes: signed integer overflow: 1871429831 + 343006811 cannot be represented in type 'int'
Fixes: 61784/clusterfuzz-testcase-minimized-ffmpeg_AV_CODEC_ID_AIC_fuzzer-5372151001120768

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 b12444fe72173ab52b6479708cfd12cb889ca300)
Signed-off-by: Michael Niedermayer <michael at niedermayer.cc>

> http://git.videolan.org/gitweb.cgi/ffmpeg.git/?a=commit;h=d5f1ecbe247d3d75ea0474556bffab017c9054d6
---

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

diff --git a/libavcodec/xvididct.c b/libavcodec/xvididct.c
index 43ea927437..dcea32210a 100644
--- a/libavcodec/xvididct.c
+++ b/libavcodec/xvididct.c
@@ -114,7 +114,7 @@ static int idct_row(short *in, const int *const tab, int rnd)
         in[5] = a1;
         in[6] = a1;
     } else {
-        const int k  = c4 * in[0] + rnd;
+        const unsigned int k  = c4 * in[0] + rnd;
         const unsigned int a0 = k + c2 * in[2] + c4 * in[4] + c6 * in[6];
         const unsigned int a1 = k + c6 * in[2] - c4 * in[4] - c2 * in[6];
         const unsigned int a2 = k - c6 * in[2] - c4 * in[4] + c2 * in[6];