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

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

Andreas Rheinhardt:
> 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.
> 
Will apply this patchset with EINVAL tonight.

- Andreas

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