[FFmpeg-devel] [PATCH 2/4] avcodec/apedec: Use 64bit in 4/3 calculation in do_apply_filter()

[Anton Khirnov]

Quoting Michael Niedermayer (2021-12-03 18:19:54)
> Fixes: Integer overflow
> Fixes: 40973/clusterfuzz-testcase-minimized-ffmpeg_AV_CODEC_ID_APE_fuzzer-6739312704618496
> 
> 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/apedec.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/libavcodec/apedec.c b/libavcodec/apedec.c
> index 9c723f29977..5c3261cf5cb 100644
> --- a/libavcodec/apedec.c
> +++ b/libavcodec/apedec.c
> @@ -1337,7 +1337,7 @@ static void do_apply_filter(APEContext *ctx, int version, APEFilter *f,
>              absres = FFABSU(res);
>              if (absres)
>                  *f->adaptcoeffs = APESIGN(res) *
> -                                  (8 << ((absres > f->avg * 3LL) + (absres > (f->avg + f->avg / 3))));
> +                                  (8 << ((absres > f->avg * 3LL) + (absres > ((int64_t)f->avg + f->avg / 3))));
>                  /* equivalent to the following code
>                      if (absres <= f->avg * 4 / 3)
>                          *f->adaptcoeffs = APESIGN(res) * 8;
> -- 
> 2.17.1

Does this not assume a 32bit int?

-- 
Anton Khirnov