[FFmpeg-devel] [PATCH 1/2] avcodec/wavpack: Check rate_x and sample rate for overflow

[David Bryant]

On 5/2/20 2:08 PM, Michael Niedermayer wrote:
> Fixes: shift exponent 32 is too large for 32-bit type 'int'
> Fixes: 21647/clusterfuzz-testcase-minimized-ffmpeg_AV_CODEC_ID_WAVPACK_fuzzer-5686168323883008
>
> 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/wavpack.c | 13 ++++++++++---
>  1 file changed, 10 insertions(+), 3 deletions(-)
>
> diff --git a/libavcodec/wavpack.c b/libavcodec/wavpack.c
> index 58ab561a15..ead57063c8 100644
> --- a/libavcodec/wavpack.c
> +++ b/libavcodec/wavpack.c
> @@ -1359,7 +1359,10 @@ static int wavpack_decode_block(AVCodecContext *avctx, int block_no,
>                  bytestream2_skip(&gb, ssize);
>                  continue;
>              }
> -            rate_x = 1 << bytestream2_get_byte(&gb);
> +            rate_x = bytestream2_get_byte(&gb);
> +            if (rate_x > 30)
> +                return AVERROR_INVALIDDATA;
> +            rate_x = 1 << rate_x;
>              dsd_mode = bytestream2_get_byte(&gb);
>              if (dsd_mode && dsd_mode != 1 && dsd_mode != 3) {
>                  av_log(avctx, AV_LOG_ERROR, "Invalid DSD encoding mode: %d\n",
> @@ -1498,9 +1501,13 @@ static int wavpack_decode_block(AVCodecContext *avctx, int block_no,
>                  av_log(avctx, AV_LOG_ERROR, "Custom sample rate missing.\n");
>                  return AVERROR_INVALIDDATA;
>              }
> -            new_samplerate = sample_rate * rate_x;
> +            new_samplerate = sample_rate;
>          } else
> -            new_samplerate = wv_rates[sr] * rate_x;
> +            new_samplerate = wv_rates[sr];
> +
> +        if (new_samplerate * (uint64_t)rate_x > INT_MAX)
> +            return AVERROR_INVALIDDATA;
> +        new_samplerate *= rate_x;
>  
>          if (multiblock) {
>              if (chan)

Looks correct to me. Thanks.