[FFmpeg-devel] [PATCH 08/10] swscale/swscale_unscaled: Fix odd height with nv24_to_yuv420p_chroma()

[Ramiro Polla]

Hi,

On Mon, Sep 23, 2024 at 12:04 AM Michael Niedermayer
<michael at niedermayer.cc> wrote:
>
> Fixes: out of array read
> Fixes: 71726/clusterfuzz-testcase-ffmpeg_SWS_fuzzer-5876893532880896
>
> Found-by: continuous fuzzing process https://github.com/google/oss-fuzz/tree/master/projects/ffmpeg
> Signed-off-by: Michael Niedermayer <michael at niedermayer.cc>
> ---
>  libswscale/swscale_unscaled.c | 2 ++
>  1 file changed, 2 insertions(+)
>
> diff --git a/libswscale/swscale_unscaled.c b/libswscale/swscale_unscaled.c
> index dc1d5f35932..d403c953cc7 100644
> --- a/libswscale/swscale_unscaled.c
> +++ b/libswscale/swscale_unscaled.c
> @@ -230,6 +230,8 @@ static void nv24_to_yuv420p_chroma(uint8_t *dst1, int dstStride1,
>      const uint8_t *src2 = src + srcStride;
>      // average 4 pixels into 1 (interleaved U and V)
>      for (int y = 0; y < h; y += 2) {
> +        if (y + 1 == h)
> +            src2 = src1;
>          for (int x = 0; x < w; x++) {
>              dst1[x] = (src1[4 * x + 0] + src1[4 * x + 2] +
>                         src2[4 * x + 0] + src2[4 * x + 2]) >> 2;

I would prefer to keep nv24_to_yuv420p_chroma() expecting height to be
a multiple of 2. We could add && !(c->srcH & 1) before selecting
nv24ToYuv420Wrapper.

Ramiro