Re: [FFmpeg-devel] [PATCH 2/4] avcodec/hevc_parse: check the size of hvcC is at least 23

[Lance Wang <lance.lmwang@gmail.com>]

On Tue, Jun 13, 2023 at 3:37 PM Zhao Zhili <quinkblack@foxmail.com> wrote:

> From: Zhao Zhili <zhilizhao@tencent.com>
>
> The code after the check skip 21 bytes and then read two bytes.
>
> Signed-off-by: Zhao Zhili <zhilizhao@tencent.com>
> ---
>  libavcodec/hevc_parse.c | 4 +++-
>  1 file changed, 3 insertions(+), 1 deletion(-)
>
> diff --git a/libavcodec/hevc_parse.c b/libavcodec/hevc_parse.c
> index 1f3beed183..7bc28fd081 100644
> --- a/libavcodec/hevc_parse.c
> +++ b/libavcodec/hevc_parse.c
> @@ -88,8 +88,10 @@ int ff_hevc_decode_extradata(const uint8_t *data, int
> size, HEVCParamSets *ps,
>
>      /* data[0] == 1 is configurationVersion from 14496-15.
>       * data[0] == 0 is for backward compatibility predates the standard.
> +     *
> +     * Minimum number of bytes of hvcC with 0 numOfArrays is 23.
>       */
> -    if (size > 3 && ((data[0] == 1) || (data[0] == 0 && (data[1] ||
> data[2] > 1)))) {
> +    if (size >= 23 && ((data[0] == 1) || (data[0] == 0 && (data[1] ||
> data[2] > 1)))) {
>

I think it's better to move the size checking before 21 byte are skipped,
or it'll go to the else logic which
is different.

         /* It seems the extradata is encoded as hvcC format. */
>          int i, j, num_arrays, nal_len_size;
>
> --
> 2.25.1
>
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