From: Ulrich Mueller <ulm@gentoo.org>
To: Stefan Monnier <monnier@IRO.UMontreal.CA>
Cc: Chong Yidong <cyd@stupidchicken.com>, emacs-devel@gnu.org
Subject: Re: "Local variables" denial-of-service attack
Date: Fri, 23 Jan 2009 09:54:18 +0100 [thread overview]
Message-ID: <18809.34234.351588.762167@a1ihome1.kph.uni-mainz.de> (raw)
In-Reply-To: <jwvvdsoifbp.fsf-monnier+emacs@gnu.org>
>>>>> On Fri, 09 Jan 2009, Stefan Monnier wrote:
>> Local Variab*les:
>> byte-compile-warnings: #1=("circular" "object" . #1#)
>> End:
> Hmm... that's not good. It's not the end of the world since it's "only"
> a DoS, but we should try and fix it. I see two ways:
> 1 - don't allow (in file-local vars and .dir-local.el) the # escapes
> that permit creation of those circular objects.
> 2 - be more careful about circularities in the
> safe-local-variable predicates.
> Nb 1 is easier and will solve it "for all cases", so it's probably
> a better choice.
But for 1 you would have to communicate to "read1" that it's reading
local variables? It's not obvious to me how one would do this in a
clean way. (I'm not very familiar with that code though).
Whereas for 2, adding a simple check like (nthcdr (safe-length foo) foo)
being nil should be sufficient in most (all?) cases.
Ulrich
next prev parent reply other threads:[~2009-01-23 8:54 UTC|newest]
Thread overview: 7+ messages / expand[flat|nested] mbox.gz Atom feed top
[not found] <18791.27439.738299.220433@a1i15.kph.uni-mainz.de>
2009-01-09 17:07 ` "Local variables" denial-of-service attack Stefan Monnier
2009-01-23 8:54 ` Ulrich Mueller [this message]
2009-02-02 3:14 ` Stefan Monnier
2009-04-02 8:15 ` Ulrich Mueller
2009-04-23 17:49 ` Ulrich Mueller
2009-04-28 2:02 ` Chong Yidong
2009-04-29 3:15 ` Chong Yidong
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