From: "Demetrios Obenour" <demetriobenour@gmail.com>
To: "'Paul Eggert'" <eggert@cs.ucla.edu>,
"'Stefan Monnier'" <monnier@iro.umontreal.ca>
Cc: 18410@debbugs.gnu.org
Subject: bug#18410: Use SAFE_ALLOCA etc. to avoid unbounded stack allocation.
Date: Sun, 7 Sep 2014 23:17:30 -0400 [thread overview]
Message-ID: <020201cfcb13$6d851890$488f49b0$@gmail.com> (raw)
In-Reply-To: <540D1699.2030903@cs.ucla.edu>
This is crucial. Otherwise, a security vulnerability could result.
MAX_ALLOCA should not be larger than the page size for the target architecture.
Demetrios Obenour
-----Original Message-----
From: bug-gnu-emacs-bounces+demetriobenour=gmail.com@gnu.org [mailto:bug-gnu-emacs-bounces+demetriobenour=gmail.com@gnu.org] On Behalf Of Paul Eggert
Sent: Sunday, September 7, 2014 10:38 PM
To: Stefan Monnier
Cc: 18410@debbugs.gnu.org
Subject: bug#18410: Use SAFE_ALLOCA etc. to avoid unbounded stack allocation.
Stefan Monnier wrote:
> MAX_ALLOCA is chosen small so that we can allocate several/many
> objects of size MAX_ALLOCA.
That's one reason, but another is that stack-overflow checking often relies on guard pages. If we blindly increase MAX_ALLOCA (or some variant of it, just for call-process) Emacs could bypass stack-overflow checking, resulting in behavior that could be worse than simply dumping core.
If I understand things correctly, Dmitry's recent stack-overflow changes don't affect this, as they don't deal with the guard-page region size.
next prev parent reply other threads:[~2014-09-08 3:17 UTC|newest]
Thread overview: 23+ messages / expand[flat|nested] mbox.gz Atom feed top
2014-09-05 6:08 bug#18410: Use SAFE_ALLOCA etc. to avoid unbounded stack allocation Paul Eggert
2014-09-05 8:45 ` Dmitry Antipov
2014-09-05 15:01 ` Paul Eggert
2014-09-05 15:44 ` Stefan Monnier
2014-09-05 16:04 ` Andreas Schwab
2014-09-05 17:22 ` Stefan Monnier
2014-09-05 8:59 ` Dmitry Antipov
2014-09-05 15:03 ` Paul Eggert
2014-09-07 7:20 ` Paul Eggert
2014-09-07 17:09 ` Eli Zaretskii
2014-09-07 20:33 ` Paul Eggert
2014-09-08 2:22 ` Stefan Monnier
2014-09-08 2:35 ` Eli Zaretskii
2014-09-08 2:43 ` Stefan Monnier
2014-09-08 2:38 ` Paul Eggert
2014-09-08 3:17 ` Demetrios Obenour [this message]
2014-09-08 3:19 ` Daniel Colascione
2014-09-08 3:20 ` Demetrios Obenour
2014-09-08 7:26 ` Dmitry Antipov
2014-09-08 2:36 ` Eli Zaretskii
2014-09-08 12:48 ` Stefan Monnier
2014-09-09 13:17 ` Eli Zaretskii
2014-09-09 13:49 ` Stefan Monnier
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