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Date: Sat, 26 Jan 2013 21:40:37 +0100
From: Frank Dittrich <frank_dittrich@...mail.com>
To: john-dev@...ts.openwall.com
Subject: Re: Segfault in Jumbo --stdout

On 01/26/2013 09:19 PM, magnum wrote:
> On 26 Jan, 2013, at 18:29 , Frank Dittrich <frank_dittrich@...mail.com> wrote:
>> On 01/26/2013 04:02 PM, Dhiru Kholia wrote:
>>> On Sat, Jan 26, 2013 at 7:01 PM, Costin Enache <e_costin@...oo.com> wrote:
>>>> ./john --rules --wordlist=password.lst --stdout
>>>>
>>>> Segmentation fault
>>>>
>>>> Something went wrong. The world list can exist or not, the segfault happens
>>>> earlier. Without using –stdout all is fine.
>>>
>>> Hi Costin,
>>>
>>> Thanks for the report.
>>>
>>> Disabling "if (!strncmp(database.format->params.label, "wpapsk", 6)"
>>> code-block in john.c (line 726) makes the problem go away.
>>>
>>> Hopefully someone familiar with this piece of code will take a look soon.
>>
>> A better fix is:
>>
>>
>> -		if (!strncmp(database.format->params.label, "wpapsk", 6) &&
>> +		if (database.format->params.label &&
>> +		    !strncmp(database.format->params.label, "wpapsk", 6) &&
>>
>>
>> But that the segfault didn't occur without --rules indicates that
>> magnum's intended fix do adjust min. length for wpapsk to 8 doesn't
>> always work.
> 
> He said without --stdout, not without --rules. So your proposed patch is the Right Fix[tm]. I will apply it.

Before I wrote the patch, I tried to reproduce the problem.
But my first attempt failed, because I used
$ ./john --wordlist=password.lst --stdout
instead of
$ ./john --rules --wordlist=password.lst --stdout

That's why I thought, when using --wordlist without --rules, the
adjustment to min-length 8 wouldn't work.
I didn't test this when I wrote my previous mail.
Now I tested it and realized that it works as expected even when using
--wordlist without --rules, provided the format tag starts with "wpapsk".

Frank

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