From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail203.messagelabs.com (mail203.messagelabs.com [216.82.254.243]) by kanga.kvack.org (Postfix) with ESMTP id 46AE36B0096 for ; Thu, 28 Jan 2010 18:27:58 -0500 (EST) Message-ID: <4B621D48.4090203@zytor.com> Date: Thu, 28 Jan 2010 15:27:04 -0800 From: "H. Peter Anvin" MIME-Version: 1.0 Subject: Re: [Security] DoS on x86_64 References: <144AC102-422A-4AA3-864D-F90183837EA3@googlemail.com> <20100128001802.8491e8c1.akpm@linux-foundation.org> <4B61B00D.7070202@zytor.com> <4B62141E.4050107@zytor.com> In-Reply-To: Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: 7bit Sender: owner-linux-mm@kvack.org To: Linus Torvalds Cc: Andrew Morton , security@kernel.org, "Luck, Tony" , James Morris , Mike Waychison , Michael Davidson , linux-mm@kvack.org, Ingo Molnar , Thomas Gleixner , Mathias Krause , Roland McGrath List-ID: On 01/28/2010 03:09 PM, Linus Torvalds wrote: > > > On Thu, 28 Jan 2010, H. Peter Anvin wrote: >> >> So this patch, *plus* removing any delayed side effects from >> SET_PERSONALITY() [e.g. the TIF_ABI_PENDING stuff in x86-64 which is >> intended to have a forward action from SET_PERSONALITY() to >> flush_thread()] might just work. I will try it out. > > Yeah, if you do that, then my "split up" patch isn't necessary. And it > would make the code a whole lot more straightforward, and remove that > whole crazy TIF_ABI_PENDING thing. > > Getting rid of the whole TIF_ABI_PENDING crap would be wonderful. It would > make SET_PERSONALITY() (and flush_thread()) way more obvious. > > So that would be much better than the untested "split up flush_old_exec" > patch I just sent out. So forget that patch, and let's go with your > further cleanup approach instead. > I think your splitup patch might still be a good idea in the sense that your flush_old_exec() is the parts that can fail. So I think the splitup patch, plus removing delayed effects, might be the right thing to do? Testing that approach now... -hpa -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@kvack.org. For more info on Linux MM, see: http://www.linux-mm.org/ . Don't email: email@kvack.org