[FFmpeg-cvslog] avcodec/mjpegdec: Fix integer overflow in DC dequantization

[Michael Niedermayer]

ffmpeg | branch: release/3.0 | Michael Niedermayer <michael at niedermayer.cc> | Wed Jan 24 03:28:49 2018 +0100| [269aecafabf84109cce914d236131afc99841cfe] | committer: Michael Niedermayer

avcodec/mjpegdec: Fix integer overflow in DC dequantization

Fixes: runtime error: signed integer overflow: -65535 * 65312 cannot be represented in type 'int'
Fixes: 4900/clusterfuzz-testcase-minimized-5769019744321536

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 1bfc1aa004950c5ad527d823a08b8a19eef34eb0)
Signed-off-by: Michael Niedermayer <michael at niedermayer.cc>

> http://git.videolan.org/gitweb.cgi/ffmpeg.git/?a=commit;h=269aecafabf84109cce914d236131afc99841cfe
---

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

diff --git a/libavcodec/mjpegdec.c b/libavcodec/mjpegdec.c
index 9a37b3251c..cefb9afdb7 100644
--- a/libavcodec/mjpegdec.c
+++ b/libavcodec/mjpegdec.c
@@ -686,7 +686,7 @@ static int decode_block(MJpegDecodeContext *s, int16_t *block, int component,
         av_log(s->avctx, AV_LOG_ERROR, "error dc\n");
         return AVERROR_INVALIDDATA;
     }
-    val = val * quant_matrix[0] + s->last_dc[component];
+    val = val * (unsigned)quant_matrix[0] + s->last_dc[component];
     val = av_clip_int16(val);
     s->last_dc[component] = val;
     block[0] = val;