[FFmpeg-devel] [PATCH 05/12] avcodec/alsdec: Avoid dereferencing context pointer in inner interleave loop

[Paul B Mahol]

lgtm

On 9/25/19, Michael Niedermayer <michael at niedermayer.cc> wrote:
> This makes the decoder faster
>
> Improves/Fixes: Timeout (22sec -> 20sec)
> Testcase:
> 17619/clusterfuzz-testcase-minimized-ffmpeg_AV_CODEC_ID_ALS_fuzzer-5078510820917248
>
> 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/alsdec.c | 10 ++++++----
>  1 file changed, 6 insertions(+), 4 deletions(-)
>
> diff --git a/libavcodec/alsdec.c b/libavcodec/alsdec.c
> index a53c170d18..56313d206c 100644
> --- a/libavcodec/alsdec.c
> +++ b/libavcodec/alsdec.c
> @@ -1815,15 +1815,17 @@ static int decode_frame(AVCodecContext *avctx, void
> *data, int *got_frame_ptr,
>      #define INTERLEAVE_OUTPUT(bps)
>          \
>      {
>          \
>          int##bps##_t *dest = (int##bps##_t*)frame->data[0];
>          \
> +        int channels = avctx->channels;
>          \
> +        int32_t **raw_samples = ctx->raw_samples;
>          \
>          shift = bps - ctx->avctx->bits_per_raw_sample;
>          \
>          if (!ctx->cs_switch) {
>          \
>              for (sample = 0; sample < ctx->cur_frame_length; sample++)
>          \
> -                for (c = 0; c < avctx->channels; c++)
>          \
> -                    *dest++ = ctx->raw_samples[c][sample] * (1U << shift);
>           \
> +                for (c = 0; c < channels; c++)
>          \
> +                    *dest++ = raw_samples[c][sample] * (1U << shift);
>          \
>          } else {
>          \
>              for (sample = 0; sample < ctx->cur_frame_length; sample++)
>          \
> -                for (c = 0; c < avctx->channels; c++)
>          \
> -                    *dest++ = ctx->raw_samples[sconf->chan_pos[c]][sample]
> * (1U << shift); \
> +                for (c = 0; c < channels; c++)
>          \
> +                    *dest++ = raw_samples[sconf->chan_pos[c]][sample] * (1U
> << shift);\
>          }
>          \
>      }
>
> --
> 2.23.0
>
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