[FFmpeg-devel] [PATCH 3/4] avcodec/h264idct_template: Fix multiple runtime error: signed integer overflow

[Steven Liu]

2017-02-27 3:28 GMT+08:00 Michael Niedermayer <michael at niedermayer.cc>:

> Fixes: 677/clusterfuzz-testcase-6635120628858880
>
> 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/h264idct_template.c | 26 +++++++++++++-------------
>  1 file changed, 13 insertions(+), 13 deletions(-)
>
> diff --git a/libavcodec/h264idct_template.c b/libavcodec/h264idct_
> template.c
> index c00900b658..9c5a43ce4f 100644
> --- a/libavcodec/h264idct_template.c
> +++ b/libavcodec/h264idct_template.c
> @@ -40,10 +40,10 @@ void FUNCC(ff_h264_idct_add)(uint8_t *_dst, int16_t
> *_block, int stride)
>      block[0] += 1 << 5;
>
>      for(i=0; i<4; i++){
> -        const int z0=  block[i + 4*0]     +  block[i + 4*2];
> -        const int z1=  block[i + 4*0]     -  block[i + 4*2];
> -        const int z2= (block[i + 4*1]>>1) -  block[i + 4*3];
> -        const int z3=  block[i + 4*1]     + (block[i + 4*3]>>1);
> +        const SUINT z0=  block[i + 4*0]     +  block[i + 4*2];
> +        const SUINT z1=  block[i + 4*0]     -  block[i + 4*2];
> +        const SUINT z2= (block[i + 4*1]>>1) -  block[i + 4*3];
> +        const SUINT z3=  block[i + 4*1]     + (block[i + 4*3]>>1);
>
>          block[i + 4*0]= z0 + z3;
>          block[i + 4*1]= z1 + z2;
> @@ -52,15 +52,15 @@ void FUNCC(ff_h264_idct_add)(uint8_t *_dst, int16_t
> *_block, int stride)
>      }
>
>      for(i=0; i<4; i++){
> -        const int z0=  block[0 + 4*i]     +  block[2 + 4*i];
> -        const int z1=  block[0 + 4*i]     -  block[2 + 4*i];
> -        const int z2= (block[1 + 4*i]>>1) -  block[3 + 4*i];
> -        const int z3=  block[1 + 4*i]     + (block[3 + 4*i]>>1);
> -
> -        dst[i + 0*stride]= av_clip_pixel(dst[i + 0*stride] + ((z0 + z3)
> >> 6));
> -        dst[i + 1*stride]= av_clip_pixel(dst[i + 1*stride] + ((z1 + z2)
> >> 6));
> -        dst[i + 2*stride]= av_clip_pixel(dst[i + 2*stride] + ((z1 - z2)
> >> 6));
> -        dst[i + 3*stride]= av_clip_pixel(dst[i + 3*stride] + ((z0 - z3)
> >> 6));
> +        const SUINT z0=  block[0 + 4*i]     +  (SUINT)block[2 + 4*i];
> +        const SUINT z1=  block[0 + 4*i]     -  (SUINT)block[2 + 4*i];
> +        const SUINT z2= (block[1 + 4*i]>>1) -  (SUINT)block[3 + 4*i];
> +        const SUINT z3=  block[1 + 4*i]     + (SUINT)(block[3 + 4*i]>>1);
> +
> +        dst[i + 0*stride]= av_clip_pixel(dst[i + 0*stride] + ((int)(z0 +
> z3) >> 6));
> +        dst[i + 1*stride]= av_clip_pixel(dst[i + 1*stride] + ((int)(z1 +
> z2) >> 6));
> +        dst[i + 2*stride]= av_clip_pixel(dst[i + 2*stride] + ((int)(z1 -
> z2) >> 6));
> +        dst[i + 3*stride]= av_clip_pixel(dst[i + 3*stride] + ((int)(z0 -
> z3) >> 6));
>      }
>
>      memset(block, 0, 16 * sizeof(dctcoef));
> --
> 2.11.0
>
> _______________________________________________
> ffmpeg-devel mailing list
> ffmpeg-devel at ffmpeg.org
> http://ffmpeg.org/mailman/listinfo/ffmpeg-devel
>

lgtm