[FFmpeg-devel] [PATCH 1/4] h264_mp4toannexb: Remove unnecessary check

[Michael Niedermayer]

On Mon, Jul 22, 2019 at 05:27:12AM +0200, Andreas Rheinhardt wrote:
> There can be at most 31 SPS and 255 PPS in the mp4/Matroska extradata.
> Given that each has a size of at most 2^16-1, the length of the output
> derived from these parameter sets can never overflow an ordinary 32 bit
> integer. So use a simple int instead of uint64_t and remove the
> unnecessary check.
> 
> Signed-off-by: Andreas Rheinhardt <andreas.rheinhardt at gmail.com>
> ---
>  libavcodec/h264_mp4toannexb_bsf.c | 8 +-------
>  1 file changed, 1 insertion(+), 7 deletions(-)
> 
> diff --git a/libavcodec/h264_mp4toannexb_bsf.c b/libavcodec/h264_mp4toannexb_bsf.c
> index fb3f24ea40..8b2899f300 100644
> --- a/libavcodec/h264_mp4toannexb_bsf.c
> +++ b/libavcodec/h264_mp4toannexb_bsf.c
> @@ -68,7 +68,7 @@ static int h264_extradata_to_annexb(AVBSFContext *ctx, const int padding)
>  {
>      H264BSFContext *s = ctx->priv_data;
>      uint16_t unit_size;
> -    uint64_t total_size                 = 0;
> +    int     total_size                  = 0;
>      uint8_t *out                        = NULL, unit_nb, sps_done = 0,
>               sps_seen                   = 0, pps_seen = 0;
>      const uint8_t *extradata            = ctx->par_in->extradata + 4;
> @@ -91,12 +91,6 @@ static int h264_extradata_to_annexb(AVBSFContext *ctx, const int padding)
>  
>          unit_size   = AV_RB16(extradata);
>          total_size += unit_size + 4;
> -        if (total_size > INT_MAX - padding) {
> -            av_log(ctx, AV_LOG_ERROR,
> -                   "Too big extradata size, corrupted stream or invalid MP4/AVCC bitstream\n");
> -            av_free(out);
> -            return AVERROR(EINVAL);
> -        }

this should be replaced by an av_assertX() to ensure that no future change
or extension exceeds the limits needed for the check to be not needed.

thanks

[...]
-- 
Michael     GnuPG fingerprint: 9FF2128B147EF6730BADF133611EC787040B0FAB

Elect your leaders based on what they did after the last election, not
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