[FFmpeg-devel] [PATCH] avcodec/scpr: Use av_memcpy_backptr() in type 17 and 33

[Paul B Mahol]

lgtm

On Tue, Jul 30, 2019 at 2:12 AM Michael Niedermayer <michael at niedermayer.cc>
wrote:

> This makes the changed code-path faster.
>
> Change not tested except with the fuzzer testcase as I found no other
> testcase.
>
> Improves: Timeout (136sec -> 74sec)
> Improves:
> 16040/clusterfuzz-testcase-minimized-ffmpeg_AV_CODEC_ID_SCPR_fuzzer-5705876062601216
>
> Found-by: continuous fuzzing process
> https://github.com/google/oss-fuzz/tree/master/projects/ffmpeg
> ---
>  libavcodec/scpr.c | 5 ++---
>  1 file changed, 2 insertions(+), 3 deletions(-)
>
> diff --git a/libavcodec/scpr.c b/libavcodec/scpr.c
> index 317950dafb..778b064841 100644
> --- a/libavcodec/scpr.c
> +++ b/libavcodec/scpr.c
> @@ -548,9 +548,8 @@ static int decode_frame(AVCodecContext *avctx, void
> *data, int *got_frame,
>              clr = bytestream2_get_le24(gb);
>          }
>          for (y = 0; y < avctx->height; y++) {
> -            for (x = 0; x < avctx->width; x++) {
> -                dst[x] = clr;
> -            }
> +            dst[0] = clr;
> +            av_memcpy_backptr(dst+1, 4, 4*avctx->width - 4);
>              dst += s->current_frame->linesize[0] / 4;
>          }
>      } else if (type == 0 || type == 1) {
> --
> 2.22.0
>
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