[FFmpeg-devel] [PATCH] Fix issue when invalid nb_index_entries value is read - SPONSORED BY INA (Institut National de l'Audiovisuel)
Cédric Le Barz
clebarz at ektacom.com
Fri Mar 24 12:22:23 EET 2023
Hi Marton,
The previous link was not OK, sorry. The good link that will make you
possible to download the sample is the following :
https://estendirectapi.ektacom.com/download/ffmpeg/Sample.mxf
Regards,
Cédric
Le 24/03/2023 à 10:13, Cédric Le Barz a écrit :
> Hi Marton,
>
> A sample can be downloaded from here :
> https://estendirectapi.ektacom.com/download/ffmpeg/
>
> Regards,
>
> Cédric
>
>
> Le 20/03/2023 à 21:03, Marton Balint a écrit :
>>
>>
>> On Mon, 20 Mar 2023, Cédric Le Barz wrote:
>>
>>> We have several samples but these are big files: about 7 GB. Is it
>>> OK to
>>> share such a file size ?
>>
>> I kind of hoped you have access to the broken muxer and can remux a
>> small file which can be made public.
>>
>> If not, then simply upload it somewhere so I can take a look. If the
>> sample can't be made public, just share it with me privately.
>>
>> Thanks,
>> Marton
>>
>>>
>>> Thanks for you answer,
>>>
>>> Regards,
>>>
>>> Cédric
>>>
>>> Le 16/03/2023 à 21:28, Marton Balint a écrit :
>>>>
>>>>
>>>> On Thu, 16 Mar 2023, Cédric Le Barz wrote:
>>>>
>>>>> Hi,
>>>>>
>>>>> By "invalid", I mean that the written nb_index_entries value does
>>>>> not
>>>>> match with the real number of entries in the table. The number of
>>>>> entries in the table is lower than the specified one. This is a
>>>>> bug in
>>>>> commercial MXFTk software (at least version V 2.8.0.0.1). It
>>>>> exists a
>>>>> lot a MXF files with this problem.
>>>>
>>>> Please share a sample. Or better yet, open a ticket for this issue
>>>> and
>>>> attach a sample there for future reference.
>>>>
>>>> Thanks,
>>>> Marton
>>>>
>>>>>
>>>>> Best regards,
>>>>>
>>>>> Cédric
>>>>>
>>>>> -----Message d'origine-----
>>>>> De : ffmpeg-devel <ffmpeg-devel-bounces at ffmpeg.org> De la part de
>>>>> Marton
>>>>> Balint
>>>>> Envoyé : mercredi 8 mars 2023 23:06
>>>>> À : FFmpeg development discussions and patches
>>>>> <ffmpeg-devel at ffmpeg.org>
>>>>> Objet : Re: [FFmpeg-devel] [PATCH] Fix issue when invalid
>>>>> nb_index_entries value is read - SPONSORED BY INA (Institut
>>>>> National de
>>>>> l'Audiovisuel)
>>>>>
>>>>>
>>>>>
>>>>> On Wed, 8 Mar 2023, Cédric Le Barz wrote:
>>>>>
>>>>>>
>>>>>> Fix issue when invalid nb_index_entries value is read : in case of
>>>>>> false nb_index_entries value, ffmpeg exit. This patch fix this
>>>>>> problem.
>>>>>
>>>>> What do you mean invalid? Is the value wrong, or is the file
>>>>> truncated in
>>>>> the middle of the index segment? From the patch it looks like the
>>>>> latter.
>>>>>
>>>>> Is there a single unluckily truncated file that you want to fix
>>>>> with this
>>>>> patch, or multiple files can be affected by this fix because e.g.
>>>>> they
>>>>> are written by the same broken muxer?
>>>>>
>>>>> Overall I am not sure if we want this applied, the user can also
>>>>> opt to
>>>>> avoid parsing all partitions with -seekable 0 and read / remux
>>>>> the file
>>>>> sequentially ignoring any index, so if somebody wants to rescue
>>>>> the data,
>>>>> it can be done as is.
>>>>>
>>>>> Regards,
>>>>> Marton
>>>>>
>>>>>>
>>>>>>
>>>>>> Signed-off-by: Cedric Le Barz <clebarz at ektacom.com>
>>>>>> ---
>>>>>> ffmpeg/libavformat/mxfdec.c | 14 ++++++++++++--
>>>>>> 1 file changed, 12 insertions(+), 2 deletions(-)
>>>>>>
>>>>>> diff --git a/ffmpeg/libavformat/mxfdec.c
>>>>>> b/ffmpeg/libavformat/mxfdec.c
>>>>>> index 4530617..ffc8987 100644
>>>>>> --- a/ffmpeg/libavformat/mxfdec.c
>>>>>> +++ b/ffmpeg/libavformat/mxfdec.c
>>>>>> @@ -1221,8 +1221,18 @@ static int
>>>>>> mxf_read_index_entry_array(AVIOContext *pb, MXFIndexTableSegment
>>>>>> *seg
>>>>>> }
>>>>>> for (i = 0; i < segment->nb_index_entries; i++) {
>>>>>> - if(avio_feof(pb))
>>>>>> - return AVERROR_INVALIDDATA;
>>>>>> +
>>>>>> + if(avio_feof(pb)) {
>>>>>> + if (i == 0) {
>>>>>> + return AVERROR_INVALIDDATA;
>>>>>> + } else {
>>>>>> + /* To be more robust to invalid
>>>>>> nb_index_entries value,
>>>>>> + fix the index entry number according to read
>>>>>> entries
>>>>>> */
>>>>>> + segment->nb_index_entries = i;
>>>>>> + return 0;
>>>>>> + }
>>>>>> + }
>>>>>> +
>>>>>> segment->temporal_offset_entries[i] = avio_r8(pb);
>>>>>> avio_r8(pb); /*
>>>>>> KeyFrameOffset */
>>>>>> segment->flag_entries[i] = avio_r8(pb);
>>>>>> --
>>>>>> 2.34.1
>>>>>>
>>>>>> _______________________________________________
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>>>>>>
>>>>>>
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