Return-path: Received: from bombadil.infradead.org ([65.50.211.133]:47522 "EHLO bombadil.infradead.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S932363AbeAHLzd (ORCPT ); Mon, 8 Jan 2018 06:55:33 -0500 Date: Mon, 8 Jan 2018 12:55:02 +0100 From: Peter Zijlstra To: Alan Cox Cc: Dan Williams , "Eric W. Biederman" , Linux Kernel Mailing List , Mark Rutland , Alan Cox , Srinivas Pandruvada , Will Deacon , Solomon Peachy , "H. Peter Anvin" , Christian Lamparter , Elena Reshetova , linux-arch@vger.kernel.org, Andi Kleen , "James E.J. Bottomley" , linux-scsi , Jonathan Corbet , X86 ML , Ingo Molnar , Alexey Kuznetsov , Zhang Rui , "Linux-media@vger.kernel.org" , Arnd Bergmann , Jan Kara , Eduardo Valentin , Al Viro , qla2xxx-upstream@qlogic.com, Thomas Gleixner , Mauro Carvalho Chehab , Arjan van de Ven , Kalle Valo , Alan Cox , "Martin K. Petersen" , Hideaki YOSHIFUJI , Greg KH , linux-wireless@vger.kernel.org, Netdev , Linus Torvalds , "David S. Miller" , Laurent Pinchart Subject: Re: [PATCH 00/18] prevent bounds-check bypass via speculative execution Message-ID: <20180108115502.GA6176@hirez.programming.kicks-ass.net> (sfid-20180108_125644_048765_EA3F656A) References: <151520099201.32271.4677179499894422956.stgit@dwillia2-desk3.amr.corp.intel.com> <87y3lbpvzp.fsf@xmission.com> <20180108100836.GF3040@hirez.programming.kicks-ass.net> <20180108114342.3b2d99fb@alans-desktop> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii In-Reply-To: <20180108114342.3b2d99fb@alans-desktop> Sender: linux-wireless-owner@vger.kernel.org List-ID: On Mon, Jan 08, 2018 at 11:43:42AM +0000, Alan Cox wrote: > On Mon, 8 Jan 2018 11:08:36 +0100 > Peter Zijlstra wrote: > > > On Fri, Jan 05, 2018 at 10:30:16PM -0800, Dan Williams wrote: > > > On Fri, Jan 5, 2018 at 6:22 PM, Eric W. Biederman wrote: > > > > In at least one place (mpls) you are patching a fast path. Compile out > > > > or don't load mpls by all means. But it is not acceptable to change the > > > > fast path without even considering performance. > > > > > > Performance matters greatly, but I need help to identify a workload > > > that is representative for this fast path to see what, if any, impact > > > is incurred. Even better is a review that says "nope, 'index' is not > > > subject to arbitrary userspace control at this point, drop the patch." > > > > I think we're focussing a little too much on pure userspace. That is, we > > should be saying under the attackers control. Inbound network packets > > could equally be under the attackers control. > > Inbound network packets don't come with a facility to read back and do > cache timimg. But could they not be used in conjunction with a local task to prime the stuff?