[FFmpeg-devel] [PATCH 1/2] avcodec/dca_xll: Fix runtime error: signed integer overflow: 2147286116 + 6298923 cannot be represented in type 'int'

[Hendrik Leppkes]

On Fri, Mar 10, 2017 at 3:24 PM, Michael Niedermayer
<michael at niedermayer.cc> wrote:
> Fixes: 732/clusterfuzz-testcase-4872990070145024
>
> See: [FFmpeg-devel] [PATCH 2/6] avcodec/dca_xll: Fix runtime error: signed integer overflow: 2147286116 + 6298923 cannot be represented in type 'int'
> Found-by: continuous fuzzing process https://github.com/google/oss-fuzz/tree/master/targets/ffmpeg
> Signed-off-by: Michael Niedermayer <michael at niedermayer.cc>
> ---
>  libavcodec/dca_xll.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/libavcodec/dca_xll.c b/libavcodec/dca_xll.c
> index 6cebda35e4..0fe90c7348 100644
> --- a/libavcodec/dca_xll.c
> +++ b/libavcodec/dca_xll.c
> @@ -1312,7 +1312,7 @@ static int combine_residual_frame(DCAXllDecoder *s, DCAXllChSet *c)
>          } else {
>              // No downmix scaling
>              for (n = 0; n < nsamples; n++)
> -                dst[n] += (src[n] + round) >> shift;
> +                dst[n] += (unsigned)((src[n] + round) >> shift);
>          }
>      }
>

audio samples are typically signed, using negative values too, is this
really safe to just cast it like that, without modifying the value in
the end?

- Hendrik