[FFmpeg-devel] [PATCH] avcodec/truemotion2: Check huffman code max bits

[Tomas Härdin]

mån 2018-11-19 klockan 23:47 +0100 skrev Michael Niedermayer:
> Fixes: Timeout
> Fixes: 10984/clusterfuzz-testcase-minimized-ffmpeg_AV_CODEC_ID_TRUEMOTION2_fuzzer-6643310750859264
> 
> 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/truemotion2.c | 19 ++++++++++++++-----
>  1 file changed, 14 insertions(+), 5 deletions(-)
> 
> diff --git a/libavcodec/truemotion2.c b/libavcodec/truemotion2.c
> index 58a577f53c..6d58483a77 100644
> --- a/libavcodec/truemotion2.c
> +++ b/libavcodec/truemotion2.c
> @@ -112,9 +112,13 @@ typedef struct TM2Huff {
>      int *lens; ///< codelengths
>  } TM2Huff;
>  
> +/**
> + *
> + * @returns the length of the longest code or an AVERROR code
> + */
>  static int tm2_read_tree(TM2Context *ctx, uint32_t prefix, int length, TM2Huff *huff)
>  {
> -    int ret;
> +    int ret, ret2;
>      if (length > huff->max_bits) {
>          av_log(ctx->avctx, AV_LOG_ERROR, "Tree exceeded its given depth (%i)\n",
>                 huff->max_bits);
> @@ -133,14 +137,14 @@ static int tm2_read_tree(TM2Context *ctx, uint32_t prefix, int length, TM2Huff *
>          huff->bits[huff->num] = prefix;
>          huff->lens[huff->num] = length;
>          huff->num++;
> -        return 0;
> +        return length;
>      } else { /* non-terminal node */
> -        if ((ret = tm2_read_tree(ctx, prefix << 1, length + 1, huff)) < 0)
> -            return ret;
> +        if ((ret2 = tm2_read_tree(ctx, prefix << 1, length + 1, huff)) < 0)
> +            return ret2;
>          if ((ret = tm2_read_tree(ctx, (prefix << 1) | 1, length + 1, huff)) < 0)
>              return ret;
>      }
> -    return 0;
> +    return FFMAX(ret, ret2);
>  }
>  
>  static int tm2_build_huff_table(TM2Context *ctx, TM2Codes *code)
> @@ -183,6 +187,11 @@ static int tm2_build_huff_table(TM2Context *ctx, TM2Codes *code)
>  
>      res = tm2_read_tree(ctx, 0, 0, &huff);
>  
> +    if (res >= 0 && res != huff.max_bits) {
> +        av_log(ctx->avctx, AV_LOG_ERROR, "Got less bits than expected: %i of %i\n",
> +               res, huff.max_bits);
> +        res = AVERROR_INVALIDDATA;
> +    }

Looks OK

/Tomas