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@niedermayer.cc>

diff --git a/libavcodec/mjpegdec.c b/libavcodec/mjpegdec.c
index e005dd0cd3bf28a7d431de872b79ff12440d9e90..5055ee28267bc69ec5161f351e7484f65b0d6611 100644 (file)
--- a/libavcodec/mjpegdec.c
+++ b/libavcodec/mjpegdec.c
@@ -715,7 +715,7 @@ 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;