From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S262352AbVEMMrm (ORCPT ); Fri, 13 May 2005 08:47:42 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S262353AbVEMMrm (ORCPT ); Fri, 13 May 2005 08:47:42 -0400 Received: from orb.pobox.com ([207.8.226.5]:36498 "EHLO orb.pobox.com") by vger.kernel.org with ESMTP id S262352AbVEMMrj (ORCPT ); Fri, 13 May 2005 08:47:39 -0400 Date: Fri, 13 May 2005 05:47:35 -0700 From: "Barry K. Nathan" To: Gabor MICSKO Cc: linux-kernel@vger.kernel.org Subject: Re: Hyper-Threading Vulnerability Message-ID: <20050513124735.GA7436@ip68-225-251-162.oc.oc.cox.net> References: <1115963481.1723.3.camel@alderaan.trey.hu> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <1115963481.1723.3.camel@alderaan.trey.hu> User-Agent: Mutt/1.5.6i Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org On Fri, May 13, 2005 at 07:51:20AM +0200, Gabor MICSKO wrote: > Is this flaw affects the current stable Linux kernels? Workaround? > Patch? Some pages with relevant information: http://www.ussg.iu.edu/hypermail/linux/kernel/0403.2/0920.html http://bugzilla.kernel.org/show_bug.cgi?id=2317 AFAICT, the workaround is something like this: 1. If possible, disable HyperThreading in BIOS. 2. If you have only one CPU, boot a UP kernel rather than SMP. 3. If you have 2 or more CPU's and you can't disable HT in the BIOS, boot with "maxcpus=n", where "n" is the number of physical CPU's in the computer (e.g. "maxcpus=2"). If you are running a kernel earlier than 2.6.5 or 2.4.26, this probably isn't going to work. If you try this, check dmesg afterward to make sure it worked properly (see the bugzilla.kernel.org URL for details). 4. If you would try #3 except you are running a 2.4.xx *vendor* kernel (not mainline), where xx < 26, try "noht". 5. If #3 and #4 don't work, try "acpi=off". Option #3 ("maxcpus=2") is what I expect to be deploying in the next several hours, FWIW... -Barry K. Nathan