[FFmpeg-devel] [PATCH 1/3] avutil/imgutils: Optimize writing 4 bytes in memset_bytes()

[Paul B Mahol]

On 12/25/18, Michael Niedermayer <michael at niedermayer.cc> wrote:
> Fixes: Timeout
> Fixes:
> 11502/clusterfuzz-testcase-minimized-ffmpeg_AV_CODEC_ID_WCMV_fuzzer-5664893810769920
> Before: Executed
> clusterfuzz-testcase-minimized-ffmpeg_AV_CODEC_ID_WCMV_fuzzer-5664893810769920
> in 11294 ms
> After : Executed
> clusterfuzz-testcase-minimized-ffmpeg_AV_CODEC_ID_WCMV_fuzzer-5664893810769920
> in 4249 ms
>
> Found-by: continuous fuzzing process
> https://github.com/google/oss-fuzz/tree/master/projects/ffmpeg
> Signed-off-by: Michael Niedermayer <michael at niedermayer.cc>
> ---
>  libavutil/imgutils.c | 6 ++++++
>  1 file changed, 6 insertions(+)
>
> diff --git a/libavutil/imgutils.c b/libavutil/imgutils.c
> index 4938a7ef67..cc38f1e878 100644
> --- a/libavutil/imgutils.c
> +++ b/libavutil/imgutils.c
> @@ -529,6 +529,12 @@ static void memset_bytes(uint8_t *dst, size_t dst_size,
> uint8_t *clear,
>          }
>      } else if (clear_size == 4) {
>          uint32_t val = AV_RN32(clear);
> +        uint64_t val8 = val * 0x100000001ULL;
> +        for (; dst_size >= 32; dst_size -= 32) {
> +            AV_WN64(dst   , val8); AV_WN64(dst+ 8, val8);
> +            AV_WN64(dst+16, val8); AV_WN64(dst+24, val8);
> +            dst += 32;
> +        }
>          for (; dst_size >= 4; dst_size -= 4) {
>              AV_WN32(dst, val);
>              dst += 4;
> --
> 2.20.1
>

NAK, implement special memset function instead.