From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Cyrus-Session-Id: sloti22d1t05-727558-1516916555-2-17334509443238788439 X-Sieve: CMU Sieve 3.0 X-Spam-known-sender: no X-Spam-score: 0.0 X-Spam-hits: BAYES_00 -1.9, HEADER_FROM_DIFFERENT_DOMAINS 0.25, RCVD_IN_DNSWL_HI -5, T_RP_MATCHES_RCVD -0.01, LANGUAGES en, BAYES_USED global, SA_VERSION 3.4.0 X-Spam-source: IP='209.132.180.67', Host='vger.kernel.org', Country='US', FromHeader='org', MailFrom='org' X-Spam-charsets: plain='us-ascii' X-Resolved-to: greg@kroah.com X-Delivered-to: greg@kroah.com X-Mail-from: stable-owner@vger.kernel.org ARC-Seal: i=1; a=rsa-sha256; cv=none; d=messagingengine.com; s=arctest; t=1516916554; b=dQ8RHKEZWb8wvx7RLtfU9ACkJC8+5XDt7gh4X3zQ6qqiGjM MdYkkb22rOKUmBUeQz17M/+NaEGexT78bAoHzAbkETlGsULmUx+SySxPcEXkhQ5B rLa9ZEUCNlR0ITGsGiOItKKvjdmZAOyg/un2d6caWY4ApmxJfzEWk+Jzd48kzP4b 9L7RtxAJ6mmSZzoCrrLhwVT5Fb3UoW8ib3e0U+kSsZjeE+lVdAceq0QjGClsrm1t 2+o3wxgg7S6X3cz8PJ0VadTpAF771PwOc9PE1o0q9lA4Vhmoj+pVMh1nYkWXZU1r e8ad0rH/JDZzt3CySkvoh+CJtJUD8CaA15XiIGQ== ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d= messagingengine.com; h=date:from:to:cc:subject:message-id :references:mime-version:content-type:in-reply-to:sender :list-id; s=arctest; t=1516916554; bh=RDvBOFSMBCntCWOlAWOqSBOGJD YW8tTGesdD6U8hIIQ=; b=v+n8dlqr+l1UkJxHjrphLuB/wkQsGFCnPbFgZzx2/V U4eYZleIZoEZBebMo9zH0d0JKKlqnd4HbxWS9rAEAljIA7EDnjv5EB6k0lQF4pkF eFH6Job6QdmQemCy7uY2R959kEwwLLFp3nRAfCdRj089MtM8XgYkO3fle87i0gWO mtLehmBsocqYq1JCCuFFBghYOJ7eyvTWLwSNcHzq7ElgeifvzqZWMlIaNFRrpgKh LQtq5jbB8j54EQL3bROk7NCvP2DLoOahOfoV0c6eUq+QU2sTtilNLSnjIy7lmsZ/ YOmE/vdVTr7BkDVYXRTlWixDqAGMBfBCyUYMhfZuJqCg== ARC-Authentication-Results: i=1; mx4.messagingengine.com; arc=none (no signatures found); dkim=fail (message has been altered; 2048-bit rsa key sha256) header.d=infradead.org header.i=@infradead.org header.b=COEbJhlm x-bits=2048 x-keytype=rsa x-algorithm=sha256 x-selector=bombadil.20170209; dmarc=none (p=none,has-list-id=yes,d=none) header.from=infradead.org; iprev=pass policy.iprev=209.132.180.67 (vger.kernel.org); spf=none smtp.mailfrom=stable-owner@vger.kernel.org smtp.helo=vger.kernel.org; x-aligned-from=fail; x-ptr=pass x-ptr-helo=vger.kernel.org x-ptr-lookup=vger.kernel.org; x-return-mx=pass smtp.domain=vger.kernel.org smtp.result=pass smtp_org.domain=kernel.org smtp_org.result=pass smtp_is_org_domain=no header.domain=infradead.org header.result=pass header_is_org_domain=yes Authentication-Results: mx4.messagingengine.com; arc=none (no signatures found); dkim=fail (message has been altered; 2048-bit rsa key sha256) header.d=infradead.org header.i=@infradead.org header.b=COEbJhlm x-bits=2048 x-keytype=rsa x-algorithm=sha256 x-selector=bombadil.20170209; dmarc=none (p=none,has-list-id=yes,d=none) header.from=infradead.org; iprev=pass policy.iprev=209.132.180.67 (vger.kernel.org); spf=none smtp.mailfrom=stable-owner@vger.kernel.org smtp.helo=vger.kernel.org; x-aligned-from=fail; x-ptr=pass x-ptr-helo=vger.kernel.org x-ptr-lookup=vger.kernel.org; x-return-mx=pass smtp.domain=vger.kernel.org smtp.result=pass smtp_org.domain=kernel.org smtp_org.result=pass smtp_is_org_domain=no header.domain=infradead.org header.result=pass header_is_org_domain=yes Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751213AbeAYVmc (ORCPT ); Thu, 25 Jan 2018 16:42:32 -0500 Received: from bombadil.infradead.org ([65.50.211.133]:53425 "EHLO bombadil.infradead.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751181AbeAYVmb (ORCPT ); Thu, 25 Jan 2018 16:42:31 -0500 Date: Thu, 25 Jan 2018 13:42:25 -0800 From: Darren Hart To: Jiri Slaby Cc: Greg Kroah-Hartman , Thomas Gleixner , linux-kernel@vger.kernel.org, stable@vger.kernel.org, Li Jinyue , peterz@infradead.org, "torvalds@linux-foundation.org" Subject: Re: [PATCH 4.14 17/89] futex: Prevent overflow by strengthen input validation Message-ID: <20180125214225.GA24122@fury> References: <20180122083954.683903493@linuxfoundation.org> <20180122083956.427607580@linuxfoundation.org> <20567b49-e0a3-e9e0-d520-74bbfc20d414@suse.cz> <20180125151219.GA16752@kroah.com> <99cabcaa-8829-d50e-afbc-920d9dbbe903@suse.cz> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <99cabcaa-8829-d50e-afbc-920d9dbbe903@suse.cz> User-Agent: Mutt/1.8.0 (2017-02-23) Sender: stable-owner@vger.kernel.org X-Mailing-List: stable@vger.kernel.org X-getmail-retrieved-from-mailbox: INBOX X-Mailing-List: linux-kernel@vger.kernel.org List-ID: On Thu, Jan 25, 2018 at 04:21:51PM +0100, Jiri Slaby wrote: > On 01/25/2018, 04:12 PM, Greg Kroah-Hartman wrote: > > On Thu, Jan 25, 2018 at 03:47:32PM +0100, Jiri Slaby wrote: > >> On 01/25/2018, 03:30 PM, Thomas Gleixner wrote: > >>> So what's the problem? > >> > >> The problem I see is that every stable kernel now requires updated > >> strace with their commit from yesterday to build correctly. In > >> particular, the new stable kernels cause rpm build failures of strace in > >> all our distros (based on those stable kernels). Sure, we can patch > >> strace in every distro every nth kernel update, but it's mere > >> impractical. Kernel should not break userspace, right? > > > > Well, when userspace is doing something stupid... :) > > No doubt... But does that mean we no longer maintain the "no userspace > breakage even if it is stupid" rule? One of the reasons we have been adding these earlier input validation checks to futex has been to mitigate security exploits taking advantage of the complex nature of the system call. Granted we should have done this initially, but if we avoid some of these nasty exploits (and the real harm they enable), then yeah, this is worth fixing userspace which is relying on undefined behavior. I'd still like to out why various distros are sending garbage to uadd2 for network setup (but that's another topic). -- Darren Hart VMware Open Source Technology Center