linux-kernel - Re: [PATCH v2] kexec: add sysctl to disable kexec

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Message-ID: <52A76348.5080803@zytor.com>
Date:	Tue, 10 Dec 2013 10:54:00 -0800
From:	"H. Peter Anvin" <hpa@...or.com>
To:	Vivek Goyal <vgoyal@...hat.com>
CC:	Kees Cook <keescook@...omium.org>,
	LKML <linux-kernel@...r.kernel.org>,
	Rik van Riel <riel@...hat.com>,
	Andrew Morton <akpm@...ux-foundation.org>,
	Matthew Garrett <matthew.garrett@...ula.com>,
	Rob Landley <rob@...dley.net>,
	Eric Biederman <ebiederm@...ssion.com>,
	Ingo Molnar <mingo@...nel.org>,
	Peter Zijlstra <peterz@...radead.org>,
	Mel Gorman <mgorman@...e.de>,
	"linux-doc@...r.kernel.org" <linux-doc@...r.kernel.org>,
	kexec@...ts.infradead.org
Subject: Re: [PATCH v2] kexec: add sysctl to disable kexec

On 12/10/2013 10:33 AM, Vivek Goyal wrote:
> On Tue, Dec 10, 2013 at 08:32:38AM -0800, H. Peter Anvin wrote:
>> Of course it isn't.
> 
> I am not sure what are you trying to say. This is too brief.
> 
> Thanks
> Vivek
> 

Of course it is not sufficient.  Once you can get arbitrary code into
kernel space (CPL 0) you can do anything, and "disabling jump back" is
just a speed bump.

	-hpa


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