Re: [FFmpeg-devel] [PATCH 1/2] avcodec/dvbsubenc: Sanity check num_rects

[Andreas Rheinhardt <andreas.rheinhardt@outlook.com>]

Michael Niedermayer:
> On Wed, Apr 16, 2025 at 11:17:30AM +0200, Andreas Rheinhardt wrote:
>> Patches attached.
>>
>> - Andreas
> 
>>  dvbsubenc.c |    3 +++
>>  1 file changed, 3 insertions(+)
>> 27ce315dbaee02f8c92c12f8c9cd0c8c7edc54fb  0001-avcodec-dvbsubenc-Sanity-check-num_rects.patch
>> From b3a4381000d13ac344114dd5f0230c9eae7b32aa Mon Sep 17 00:00:00 2001
>> From: Andreas Rheinhardt <andreas.rheinhardt@outlook.com>
>> Date: Wed, 16 Apr 2025 10:23:01 +0200
>> Subject: [PATCH 1/2] avcodec/dvbsubenc: Sanity check num_rects
>> MIME-Version: 1.0
>> Content-Type: text/plain; charset=UTF-8
>> Content-Transfer-Encoding: 8bit
>>
>> It is written as region_id which is a single byte.
>> Also fixes a potential (defined) overflow in the num_rects * 6
>> multiplication later; this has been found by 김승호 <kimsho98@naver.com>.
>>
>> Signed-off-by: Andreas Rheinhardt <andreas.rheinhardt@outlook.com>
>> ---
>>  libavcodec/dvbsubenc.c | 3 +++
>>  1 file changed, 3 insertions(+)
>>
>> diff --git a/libavcodec/dvbsubenc.c b/libavcodec/dvbsubenc.c
>> index 822e3a5309..8eeac76855 100644
>> --- a/libavcodec/dvbsubenc.c
>> +++ b/libavcodec/dvbsubenc.c
>> @@ -284,6 +284,9 @@ static int dvbsub_encode(AVCodecContext *avctx, uint8_t *outbuf, int buf_size,
>>      if (h->num_rects && !h->rects)
>>          return AVERROR(EINVAL);
>>  
>> +    if (h->num_rects >= 256)
>> +        return AVERROR_INVALIDDATA;
> 
> should this not be AVERROR(EINVAL); ?
> 

I pondered this myself and it is not clear to me: It depends on whether
one considers num_rects data or a parameter. I'll change it.

- Andreas

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