[FFmpeg-devel] [PATCH]lavc/h264_ps: Check chroma_location limits

[Carl Eugen Hoyos]

2017-03-24 10:59 GMT+01:00 wm4 <nfxjfg at googlemail.com>:
> On Fri, 24 Mar 2017 10:40:21 +0100
> Carl Eugen Hoyos <cehoyos at ag.or.at> wrote:
>
>> From 1c249440c62271565be12112f321ad9aa6a922fb Mon Sep 17 00:00:00 2001
>> From: Carl Eugen Hoyos <cehoyos at ag.or.at>
>> Date: Fri, 24 Mar 2017 10:38:22 +0100
>> Subject: [PATCH] lavc/h264_ps: Check that chroma_location is within limits.
>>
>> Fixes ticket #6255.
>> ---
>>  libavcodec/h264_ps.c |    2 ++
>>  1 file changed, 2 insertions(+)
>>
>> diff --git a/libavcodec/h264_ps.c b/libavcodec/h264_ps.c
>> index b78ad25..55e6a6e 100644
>> --- a/libavcodec/h264_ps.c
>> +++ b/libavcodec/h264_ps.c
>> @@ -181,6 +181,8 @@ static inline int decode_vui_parameters(GetBitContext *gb, AVCodecContext *avctx
>>      if (get_bits1(gb)) {
>>          /* chroma_sample_location_type_top_field */
>>          avctx->chroma_sample_location = get_ue_golomb(gb) + 1;
>> +        if (avctx->chroma_sample_location >= AVCHROMA_LOC_NB)
>> +            avctx->chroma_sample_location = AVCHROMA_LOC_UNSPECIFIED;
>
> AVCHROMA_LOC_NB is not part of the libavutil ABI, so libavcodec can in
> theory not use it.

I suspect you misread this rule (we cannot make _NB smaller), in any case
please look a few lines up from the patch, there are several similar
cases there.

Carl Eugen