[poppler] Do we need to remove the internal DCT and JPX decoders

Carlos Garcia Campos carlosgc at gnome.org
Thu May 18 15:51:54 UTC 2017

Albert Astals Cid <aacid at kde.org> writes:

> El dimarts, 16 de maig de 2017, a les 19:40:31 CEST, jose.aliste at gmail.com va 
> escriure:
>> Hey List,
>> very recently, Thalos(CISCO) has encountered some overflows that could
>> potentially lead to security risks. One of this is in the DCT decoder and
>> the other in the JPX decoder. The question is what to do? Do we fix these
>> overflows or just remove the decoders from poppler since they are not being
>> mantained. One of the problems is that Ubuntu is compiled by default to use
>> the JPX decoder while most distributions do include libjpeg support.
>> The bugs as I understand are still private, so if any of the developers of
>> poppler wants to see the reports, please contact me directly (off list) and
>> I will send it to you together with a minimal pdf sample.
> Right now we "almost silently" fall back to the unsupported code, yes we put a 
> warning at the very end of the configure/cmake process but i guess hardly 
> anyone reads those.
> My suggestion would be change the configure/cmake process so it behaves like 
> this (process explained for libjpeg but same would apply for libopenjpeg)
>  * You have libjpeg -> all is good
>  * You don't have it, configure fails
>     * Unless you pass one of these two options
>          * --dct-decoder=unmaintained
>          * --dct-decoder=none
> Which would give you either the unmaintained decoder or none at all.

Sounds good to me.

> At least this way we can totally pass the blame for distros for using either 
> the unmaintained or the none flags.
> I am suggesting this instead of removing it because for some controlled 
> reasons it may be actually better to be able to use the unmaintained decoders 
> than nothing (e.g. you're running pdftotext inside a virtual machine, doesn't 
> matter if you get "rooted" inside the virtual machine).
> Cheers,
>   Albert
>> Kind regards
>> José
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Carlos Garcia Campos
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