From: Kees Cook <kees.cook@canonical.com>
To: "H. Peter Anvin" <hpa@zytor.com>
Cc: Arjan van de Ven <arjan@infradead.org>,
Thomas Gleixner <tglx@linutronix.de>,
Ingo Molnar <mingo@redhat.com>,
x86@kernel.org, Pekka Enberg <penberg@cs.helsinki.fi>,
Jan Beulich <jbeulich@novell.com>,
Vegard Nossum <vegardno@ifi.uio.no>,
Yinghai Lu <yinghai@kernel.org>,
Jeremy Fitzhardinge <jeremy.fitzhardinge@citrix.com>,
linux-kernel@vger.kernel.org
Subject: Re: [PATCH v4] [x86] detect and report lack of NX protections
Date: Tue, 10 Nov 2009 08:57:38 -0800 [thread overview]
Message-ID: <20091110165738.GH5129@outflux.net> (raw)
In-Reply-To: <4AF9991B.20400@zytor.com>
On Tue, Nov 10, 2009 at 08:47:23AM -0800, H. Peter Anvin wrote:
> On 11/10/2009 07:49 AM, Kees Cook wrote:
> >>
> >> The second clause can only get executed if CONFIG_X86_PAE is unset,
> >> which in turn means _PAGE_NX == 0... so that piece of code is meaningless.
> >
> > CONFIG_X86_PAE is unset for x86_64, where _PAGE_NX is valid. (This was
> > the main situation I was trying to address.) So that chunk runs for
> > non-pae 32bit, and all 64bit:
> >
>
> In reality, X86_PAE really should have been defined for 64 bits, since
> 64 bits really is PAE in most aspects.
>
> Anyway, for the 64-bit case it looks like the proper place for any of
> this is in check_efer() just below, not in this null routine.
64-bit does not set nx_enabled to "1" by default anywhere. And setting
the default to 1 in check_efer() seemed out of place to me.
-Kees
--
Kees Cook
Ubuntu Security Team
next prev parent reply other threads:[~2009-11-10 16:58 UTC|newest]
Thread overview: 23+ messages / expand[flat|nested] mbox.gz Atom feed top
2009-10-19 18:42 [PATCH] [x86] detect and report lack of NX protections Kees Cook
2009-10-19 23:43 ` Arjan van de Ven
2009-10-20 2:04 ` [PATCH v2] " Kees Cook
2009-10-20 2:18 ` H. Peter Anvin
2009-10-20 4:44 ` Kees Cook
2009-10-20 4:55 ` [PATCH v3] " Kees Cook
2009-11-09 22:10 ` [PATCH v4] " Kees Cook
2009-11-09 23:16 ` H. Peter Anvin
2009-11-10 15:49 ` Kees Cook
2009-11-10 16:47 ` H. Peter Anvin
2009-11-10 16:57 ` Kees Cook [this message]
2009-11-10 17:12 ` H. Peter Anvin
2009-11-10 17:46 ` Kees Cook
2009-11-10 18:53 ` H. Peter Anvin
2009-11-10 19:43 ` Kees Cook
2009-11-10 19:59 ` H. Peter Anvin
2009-11-10 20:55 ` Kees Cook
2009-11-10 21:22 ` H. Peter Anvin
2009-11-10 22:15 ` Kees Cook
2009-11-10 22:25 ` H. Peter Anvin
2009-11-12 18:01 ` Yuhong Bao
2009-11-10 20:25 ` H. Peter Anvin
2009-11-10 16:55 ` [PATCH v5] " Kees Cook
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=20091110165738.GH5129@outflux.net \
--to=kees.cook@canonical.com \
--cc=arjan@infradead.org \
--cc=hpa@zytor.com \
--cc=jbeulich@novell.com \
--cc=jeremy.fitzhardinge@citrix.com \
--cc=linux-kernel@vger.kernel.org \
--cc=mingo@redhat.com \
--cc=penberg@cs.helsinki.fi \
--cc=tglx@linutronix.de \
--cc=vegardno@ifi.uio.no \
--cc=x86@kernel.org \
--cc=yinghai@kernel.org \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is an external index of several public inboxes,
see mirroring instructions on how to clone and mirror
all data and code used by this external index.