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http://bugs.exim.org/show_bug.cgi?id=1062
--- Comment #2 from Andrey N. Oktyabrski <ano@???> 2011-01-13 07:28:22 ---
(In reply to comment #1)
> The only proponent is using recursion in ACL invocation based upon URLs
> encountered in a message body. Changing the maximum recursion depth just moves
> the problem around, it doesn't fix anything. But because the incident rate
> drops, people stop paying attention to the actual problem: with a sufficiently
> broken configuration, which pushes stack frames, with the number of those stack
> frames based upon content under attacker control, stack overflows will happen.
> Increasing the count permitted by Exim just increases the odds of encountering
> an OS ulimit.
What you think about the configuration option "acl_recursion_depth" with
hardcoded maximum value 200 and default 20? I can made this patch if it
pointful.
> Do not use recursion in ACLs based upon message body content.
Not all things can be made by the ${reduce ...}
How can I iterate through, for example, ${lookup dnsdb ...} result? Or
$recipients list?
I would not use recursion if something same as "while" cycle exists. But in
exim configuration I have not any cycle operator.
> The proponent's asked for other ways to do this and another mechanism was
> pointed out at the time. He has neglected to change his set-up but instead
> wants us to encourage bad practice.
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