DomainKey-Signature: a=rsa-sha1; c=nofws;
        d=gmail.com; s=gamma;
        h=mime-version:in-reply-to:references:from:date:message-id:subject:to
         :cc:content-type;
        b=Z4v5Wpgue3EOVVxClfVN1nUQirMAO7OSJEhWXX/E10lpYFOq9PNMn4hswh5nntYaYu
         Oa6rXP1D0W+cMXkjqBnVFqTU7RZb9YQa1XraRoMmOEkhnHeZApU42ZpZGyG78ppoJIJz
         w5wXAR9Argc0+jLscAOjjkJaV3WQmy0Crnu80=
MIME-Version: 1.0
In-Reply-To: <20091111093258.GE560@1wt.eu>
References: <4AF9D8E2.7050205@zytor.com> <4AF9E61B.5090407@zytor.com> 
	<20091110222031.GA22911@elte.hu> <20091110224222.GA28648@1wt.eu> 
	<4AF9ED78.3000106@zytor.com> <20091111055220.GA560@1wt.eu> 
	<4AFA569E.9040206@zytor.com> <20091111063617.GD560@1wt.eu> 
	<4AFA6E50.7030808@zytor.com> <20091111093258.GE560@1wt.eu>
From: Matt Thrailkill <matt.thrailkill@gmail.com>
Date: Wed, 11 Nov 2009 18:23:14 -0800
Message-ID: <a91053ef0911111823v52669d18p7e5812076a63f03e@mail.gmail.com>
Subject: Re: i686 quirk for AMD Geode
To: Willy Tarreau <w@1wt.eu>
Cc: "H. Peter Anvin" <hpa@zytor.com>, Ingo Molnar <mingo@elte.hu>,
       Pavel Machek <pavel@ucw.cz>, Avi Kivity <avi@redhat.com>,
       Alan Cox <alan@lxorguk.ukuu.org.uk>,
       Matteo Croce <technoboy85@gmail.com>,
       Sven-Haegar Koch <haegar@sdinet.de>, linux-kernel@vger.kernel.org
Content-Type: text/plain; charset=ISO-8859-1
Sender: linux-kernel-owner@vger.kernel.org
Content-Length: 1019
Lines: 19

On Wed, Nov 11, 2009 at 1:32 AM, Willy Tarreau <w@1wt.eu> wrote:
> All I can say is that executing a NOP results in no state change in
> the processor except the instruction pointer which points to the
> next instruction after execution. Since a NOP changes nothing, it
> cannot be used alone to provide any privilege, access to data or
> any such thing. Since it does not perform any jump, it cannot either
> be used to take back control of the execution flow. And it is certain
> that the next instruction after it will be executed, so if the NOP
> crosses a page boundary and completes on a non-executable one, the
> next instruction will trigger the PF.
>
> So I can't see how a NOP can be used to circumvent any protection.

So a nop(l) sled won't be a problem, right?
--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@vger.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/