[FFmpeg-devel] [PATCH 1/3] avcodec/hevc_sei: check size before using it

[mypopy at gmail.com]

On Tue, Sep 14, 2021 at 6:50 PM <lance.lmwang at gmail.com> wrote:
>
> From: Limin Wang <lance.lmwang at gmail.com>
>
> Signed-off-by: Limin Wang <lance.lmwang at gmail.com>
> ---
>  libavcodec/hevc_sei.c | 31 +++++++++++++++++++++++++------
>  1 file changed, 25 insertions(+), 6 deletions(-)
>
> diff --git a/libavcodec/hevc_sei.c b/libavcodec/hevc_sei.c
> index 2c326bf..29d0346 100644
> --- a/libavcodec/hevc_sei.c
> +++ b/libavcodec/hevc_sei.c
> @@ -52,9 +52,13 @@ static int decode_nal_sei_decoded_picture_hash(HEVCSEIPictureHash *s, GetBitCont
>      return 0;
>  }
>
> -static int decode_nal_sei_mastering_display_info(HEVCSEIMasteringDisplay *s, GetBitContext *gb)
> +static int decode_nal_sei_mastering_display_info(HEVCSEIMasteringDisplay *s, GetBitContext *gb, int size)
>  {
>      int i;
> +
> +    if (size < 24)
> +        return AVERROR_INVALIDDATA;
> +
I can't find more information about this change, is it the old code
leading some issue?

>      // Mastering primaries
>      for (i = 0; i < 3; i++) {
>          s->display_primaries[i][0] = get_bits(gb, 16);
> @@ -67,23 +71,32 @@ static int decode_nal_sei_mastering_display_info(HEVCSEIMasteringDisplay *s, Get
>      // Max and min luminance of mastering display
>      s->max_luminance = get_bits_long(gb, 32);
>      s->min_luminance = get_bits_long(gb, 32);
> +    size -= 24;
>
>      // As this SEI message comes before the first frame that references it,
>      // initialize the flag to 2 and decrement on IRAP access unit so it
>      // persists for the coded video sequence (e.g., between two IRAPs)
>      s->present = 2;
> +
> +    skip_bits_long(gb, 8 * size);
>      return 0;
>  }
>
> -static int decode_nal_sei_content_light_info(HEVCSEIContentLight *s, GetBitContext *gb)
> +static int decode_nal_sei_content_light_info(HEVCSEIContentLight *s, GetBitContext *gb, int size)
>  {
> +    if (size < 4)
> +        return AVERROR_INVALIDDATA;
> +
>      // Max and average light levels
>      s->max_content_light_level     = get_bits(gb, 16);
>      s->max_pic_average_light_level = get_bits(gb, 16);
> +    size -= 4;
>      // As this SEI message comes before the first frame that references it,
>      // initialize the flag to 2 and decrement on IRAP access unit so it
>      // persists for the coded video sequence (e.g., between two IRAPs)
>      s->present = 2;
> +
> +    skip_bits_long(gb, 8 * size);
>      return  0;
>  }
>
> @@ -342,10 +355,16 @@ static int decode_nal_sei_active_parameter_sets(HEVCSEI *s, GetBitContext *gb, v
>      return 0;
>  }
>
> -static int decode_nal_sei_alternative_transfer(HEVCSEIAlternativeTransfer *s, GetBitContext *gb)
> +static int decode_nal_sei_alternative_transfer(HEVCSEIAlternativeTransfer *s, GetBitContext *gb, int size)
>  {
> +    if (size < 1)
> +        return AVERROR_INVALIDDATA;
> +
>      s->present = 1;
>      s->preferred_transfer_characteristics = get_bits(gb, 8);
> +    size--;
> +
> +    skip_bits_long(gb, 8 * size);
>      return 0;
>  }
>
> @@ -451,9 +470,9 @@ static int decode_nal_sei_prefix(GetBitContext *gb, void *logctx, HEVCSEI *s,
>      case SEI_TYPE_PIC_TIMING:
>          return decode_nal_sei_pic_timing(s, gb, ps, logctx, size);
>      case SEI_TYPE_MASTERING_DISPLAY_COLOUR_VOLUME:
> -        return decode_nal_sei_mastering_display_info(&s->mastering_display, gb);
> +        return decode_nal_sei_mastering_display_info(&s->mastering_display, gb, size);
>      case SEI_TYPE_CONTENT_LIGHT_LEVEL_INFO:
> -        return decode_nal_sei_content_light_info(&s->content_light, gb);
> +        return decode_nal_sei_content_light_info(&s->content_light, gb, size);
>      case SEI_TYPE_ACTIVE_PARAMETER_SETS:
>          return decode_nal_sei_active_parameter_sets(s, gb, logctx);
>      case SEI_TYPE_USER_DATA_REGISTERED_ITU_T_T35:
> @@ -461,7 +480,7 @@ static int decode_nal_sei_prefix(GetBitContext *gb, void *logctx, HEVCSEI *s,
>      case SEI_TYPE_USER_DATA_UNREGISTERED:
>          return decode_nal_sei_user_data_unregistered(&s->unregistered, gb, size);
>      case SEI_TYPE_ALTERNATIVE_TRANSFER_CHARACTERISTICS:
> -        return decode_nal_sei_alternative_transfer(&s->alternative_transfer, gb);
> +        return decode_nal_sei_alternative_transfer(&s->alternative_transfer, gb, size);
>      case SEI_TYPE_TIME_CODE:
>          return decode_nal_sei_timecode(&s->timecode, gb);
>      case SEI_TYPE_FILM_GRAIN_CHARACTERISTICS:
> --
> 1.8.3.1
>
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-- 
=======================================
Jun zhao/赵军
+++++++++++++++++++++++++++++++++++++++