avcodec/ralf: use multiply instead of shift to avoid undefined behavior in decode_block()

Fixes: left shift of negative value -249
Fixes: 18566/clusterfuzz-testcase-minimized-ffmpeg_AV_CODEC_ID_RALF_fuzzer-5649394561187840
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/ralf.c b/libavcodec/ralf.c
index 1d881cf7ae396b876e991d4d69ad35a0a10cf2d9..ca8817aa21ecb70138f0b9af3b792942ab272bb3 100644 (file)
--- a/libavcodec/ralf.c
+++ b/libavcodec/ralf.c
@@ -408,7 +408,7 @@ static int decode_block(AVCodecContext *avctx, GetBitContext *gb,
     case 4:
         for (i = 0; i < len; i++) {
             t  =   ch1[i] + ctx->bias[1];
-            t2 = ((ch0[i] + ctx->bias[0]) << 1) | (t & 1);
+            t2 = ((ch0[i] + ctx->bias[0]) * 2) | (t & 1);
             dst0[i] = (t2 + t) / 2;
             dst1[i] = (t2 - t) / 2;
         }