From mboxrd@z Thu Jan  1 00:00:00 1970
From: Marius Bakke <mbakke@fastmail.com>
Subject: bug#27429: Stack clash (CVE-2017-1000366 etc); -fstack-check
Date: Sun, 25 Jun 2017 12:41:06 +0200
Message-ID: <87o9tcnyd9.fsf@fastmail.com>
References: <20170619222550.GA29289@jasmine.lan>
	<20170625113828.024a425f@scratchpost.org>
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To: Danny Milosavljevic <dannym@scratchpost.org>, 27429@debbugs.gnu.org

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Danny Milosavljevic <dannym@scratchpost.org> writes:

> Hi,
>
> what do you all think of rebuilding the world with "-fstack-check" (either now or later on) ?
>
> That would make gcc emit code to always grow the stack in a way that it certainly touches each 4 KiB (parametrizable by STACK_CHECK_PROBE_INTERVAL_EXP) page on the way.
>
> I think that would be the right and permanent fix - unlike the whack-a-mole approach where we patch programs not to do what they are supposed to do, if their stack allocation happens to grow.
>
> See also <https://www.qualys.com/2017/06/19/stack-clash/stack-clash.txt> and <https://gcc.gnu.org/onlinedocs/gccint/Stack-Checking.html>.

Red Hat investigated this during the embargo[0] and found that the
current implementation in GCC has problems[1]. We should wait until
those issues are resolved first, but sounds good to me.

[0] http://seclists.org/oss-sec/2017/q2/556
[1] http://seclists.org/oss-sec/2017/q2/505

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