[sword-devel] Segfault in LZSS code

[David Haslam]

Still unanswered is Bastian’s good question “Why is it the default then?”

David

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On Sun, Feb 28, 2021 at 03:06, Troy A. Griffitts <scribe at crosswire.org> wrote:

> While I agree we probably shouldn't segfault, this is a bit like
> renaming xyz.exe to xyz.doc and trying to open it in Word.
>
> Not that is matters, but the details are that the LZSS decompressor
> treats the entire block as uncompressed binary (because it doesn't
> encounter any compression block signatures, because the data is not LZSS
> data but instead ZIP encoded data) and does nothing with any of it,
> returning the zip compressed data as-is, resulting in binary gibberish
> when we reference it, so when we pull offset and size values from the
> "uncompressed" block (which really isn't uncompressed), we get
> essentially random numbers... which causes things to crash. Not sure
> what Word does when you give it a ".doc" file which is a binary, or
> MySQL does when you cat /dev/random > /var/data/mysql/ibdata1, but I
> would bet it doesn't behave very well.
>
> I would say the solution to this is don't give the LZSS filters ZIP
> compressed data. I can try to put some sanity checks in when I read the
> offset, size values from the "uncompressed" data and might be able to
> prevent a crash.
>
> Troy
>
> On 2/27/21 10:19 AM, Bastian Germann wrote:
>> Am 27.02.21 um 17:47 schrieb refdoc at gmx.net:
>>> Could you put a bug report into JIRA?
>>
>> https://tracker.crosswire.org/browse/API-247
>>
>>> As such the LZSS code is experimental and should not be relied upon.
>>>
>>
>> Why is it the default then? (according to
>> https://wiki.crosswire.org/DevTools:conf_Files#Required_Elements_with_defaults)
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