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Date: Thu, 7 Aug 2008 14:24:04 +0200
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Message-ID: <200808071424.04620.arnaud.lb@gmail.com>
Subject: PCRE and recursion: NO_RECURSE flag
From: arnaud.lb@gmail.com (Arnaud Le Blanc)

Hi,

PCRE can be highly recursive [1] and this can cause segmentation faults [2]. 
This is a known problem and the pcre ini settings avoids the segfaults, but 
the execution of the expression will fail anyway.

PCRE has a NO_RECURSE flag which makes the match() internal function no 
recursive and avoids this problem. The configure switch for this option is --
disable-stack-for-recursion. NO_RECURSE is documented in pcre_exec.c.

This can be easily enabled [3] for the bundled PCRE. It seems to be safe to 
enable that. Actually the PCRE test suite pass with NO_RECURSE enabled, and 
segfaults without. Can this be enabled ?

[1] http://manpages.courier-mta.org/htmlman3/pcrestack.3.html
[2] http://bugs.php.net/bug.php?id=45735
[3] http://arnaud.lb.s3.amazonaws.com/pcre_no_recurse.patch

Regards,

Arnaud