[FFmpeg-devel] [PATCH 5/5] avcodec/ralf: use multiply instead of shift to avoid undefined behavior in decode_block()

[Michael Niedermayer]

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 at niedermayer.cc>
---
 libavcodec/ralf.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/libavcodec/ralf.c b/libavcodec/ralf.c
index 1d881cf7ae..ca8817aa21 100644
--- 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;
         }
-- 
2.23.0