[FFmpeg-devel] [PATCH 5/6] avcodec/bonk: Avoid undefined overflow in quant

Paul B Mahol onemda at gmail.com
Wed Jan 11 23:06:44 EET 2023


On 1/11/23, Michael Niedermayer <michael at niedermayer.cc> wrote:
> Fixes: signed integer overflow: -2889074 * 2048 cannot be represented in
> type 'int'
> Fixes:
> 51363/clusterfuzz-testcase-minimized-ffmpeg_AV_CODEC_ID_BONK_fuzzer-5660734784143360
> Fixes:
> 48567/clusterfuzz-testcase-minimized-ffmpeg_AV_CODEC_ID_BONK_fuzzer-6617680050520064
> Fixes:
> 48567/clusterfuzz-testcase-minimized-ffmpeg_AV_CODEC_ID_BONK_fuzzer-6743951854141440
>
> No check is done for the overflow as this was rejected in last review, see
> the ML
>
> Note: the 2nd and 3rd testcase was assigned by ossfuzz to a unrelated theora
> issue (48567)
>
> 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/bonk.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/libavcodec/bonk.c b/libavcodec/bonk.c
> index 5d736b1563..9e176d5477 100644
> --- a/libavcodec/bonk.c
> +++ b/libavcodec/bonk.c
> @@ -356,7 +356,7 @@ static int bonk_decode(AVCodecContext *avctx, AVFrame
> *frame,
>                  sample++;
>              }
>
> -            sample[0] = predictor_calc_error(s->k, state, s->n_taps,
> s->input_samples[i] * quant);
> +            sample[0] = predictor_calc_error(s->k, state, s->n_taps,
> s->input_samples[i] * (unsigned)quant);
>              sample++;
>          }
>
> --
> 2.17.1
>

LGTM

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