[pcre-dev] [Bug 2293] Dos attack via control regex

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Author: admin
Date:  
To: pcre-dev
Subject: [pcre-dev] [Bug 2293] Dos attack via control regex
https://bugs.exim.org/show_bug.cgi?id=2293

Philip Hazel <ph10@???> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
         Resolution|---                         |INVALID
             Status|NEW                         |RESOLVED


--- Comment #1 from Philip Hazel <ph10@???> ---
Your example is clearly using PCRE1, because it calls pcre_compile() and
pcre_study() and you mention libpcre. It would not compile with 10.31 as you
have stated. You must actually be using a release in the 8.xx series. Since
release 10.30 PCRE2 has been refactored so as not to use the stack in the way
PCRE1 does. Instead, the heap is used.

Having said that, there are many ways of writing patterns that have in effect
to search a very large tree, and this can cause stack overflow in PCRE1. There
are several limits that the programmer can apply to stop this. Programs that
accept patterns from unknown sources should always set some limits. Please see
the pcrestack man page and other parts of the PCRE1 documentation.

PCRE2, as I said above, no longer uses the stack in this way, but limits are
still available to control how much heap it uses.

This is not a bug.

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