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Bug #55035 pcre_exec() deadlock causing Segmentation fault (11)
Submitted: 2011-06-11 15:52 UTC Modified: 2011-06-11 17:10 UTC
From: jimmy dot axenhus at gmail dot com Assigned:
Status: Not a bug Package: PCRE related
PHP Version: 5.3.6 OS: Ubuntu 11.04 and Trisquel 4.5
Private report: No CVE-ID: None
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 [2011-06-11 15:52 UTC] jimmy dot axenhus at gmail dot com 
Description:
------------
It appears that PHP can deadlock in pcre_exec(), repeatingly calling a function(itself?).

Was converting a vBulletin forum to phpBB, therefore might be hard to reproduce. Despite that I managed to reproduce it on three different computers.

I spent several hours debugging this, and will dig deeper into the code that caused this problem to find the specific string causing this. Expect more debug data soon.

Test script:
---------------
phpBB 3.0.8, converting from vBulletin 3.8.x, with code attached to http://www.phpbb.com/community/viewtopic.php?f=65&t=1722325#p10391895
You also need a database to convert.

Expected result:
----------------
Normal phpBB progress when converting (php deliving an HTML page)

Actual result:
--------------
PHP delivered a blank php script file to the browser and apache logged a segfault (11). After a very long session trying to debug this I finally managed to generate a stacktrace with gdb. The resource below will be accessible as long as this bug is unresolved.
http://jimmy.axenhus.com/gdb.txt

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 [2011-06-11 16:52 UTC] felipe@php.net
-Status: Open +Status: Bogus
 [2011-06-11 16:52 UTC] felipe@php.net 
Try setting a bigger pcre.backtrack_limit and pcre.recursion_limit.

See http://docs.php.net/manual/en/pcre.configuration.php
 [2011-06-11 17:10 UTC] jimmy dot axenhus at gmail dot com 
That does not solve the problem, still get a segfault :(
 
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