From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Cyrus-Session-Id: sloti22d1t05-49867-1516894259-2-9413302014468134768 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=1516894259; b=tXQYHdP6Quvhh7sQzl8M6lbyZgrpN/9AHXSpBxLGtFDjNkG EAtbSEXe1tWMZxDc2VwHbwEKN3vfrbK/Q8sCxBWAqEwdeySVreYyiZeUdApCuQNh t2qPU8u2Gi8pAwf8HL+GK9CmB8Tcc16fRoENKB+h/bC+7XCgsBYb/K4FaMZQOKrb LfVuBmOXfhA1R8XY1Gw1Aic2dKxZEbktFGmgi3hGmKjk4vq6r+0Sv+Hm3aZQ+qaT Ze0H3W6BZtfN+yHdE4T3Cai1lAf3wmNPEw/mdVr6Walr8lkG8VETUmMGLOSFTeto alcO/GCIlfiaUzTHjYWUr7nAqv69eN7Na9wLRrA== 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=1516894259; bh=yQ6H1TZreDDhkIuFoT4VeQatVr 8vIh/x0jqZq6R320k=; b=ssCJlSvgEFmOjals0jdlMOe08or17Rnjwu8Nz14QZa y/lCiJ/coMNZaGq5ymvPReto18vOv+xEwor73FJ+qvZlmZwfAIwp4EcaVWlhdKew ZTXCduN8XAD1bn2b3M52dzMXsBV8znCAmkD4VAD6UfhwtNSVo21R43M5fUhbtC2E Mr5k/sPxbHGgootgLYDX+yCKhX70Tv3zD0P38FY+DcjZ7Rio0/oOKuqskawlyiLq sOjoLKkCCGChuWT3iQStjKnBi+tr33I9lYrOx+j2WahR3H3NrN+wkt1/lEsYFPch 92IvMRsP2rgjeyNO5sQ/UAkaShC1e5MLnRELW+nk3kIA== ARC-Authentication-Results: i=1; mx2.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=X7MgIzya 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: mx2.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=X7MgIzya 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 S1751199AbeAYPa5 (ORCPT ); Thu, 25 Jan 2018 10:30:57 -0500 Received: from bombadil.infradead.org ([65.50.211.133]:57715 "EHLO bombadil.infradead.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751170AbeAYPa4 (ORCPT ); Thu, 25 Jan 2018 10:30:56 -0500 Date: Thu, 25 Jan 2018 16:30:45 +0100 From: Peter Zijlstra To: Jiri Slaby Cc: Greg Kroah-Hartman , Thomas Gleixner , linux-kernel@vger.kernel.org, stable@vger.kernel.org, Li Jinyue , dvhart@infradead.org, "torvalds@linux-foundation.org" Subject: Re: [PATCH 4.14 17/89] futex: Prevent overflow by strengthen input validation Message-ID: <20180125153045.GL2269@hirez.programming.kicks-ass.net> 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/1.9.2 (2017-12-15) 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: > > The same reason it was applied upstream, it fixes a reported > > issue. > > > > Does that mean that all UBSAN overflow error reports are not valid > > because of how we build the kernel? > > IMO yes, because with the option, signed overflow is not undefined. > > In the long term, it would be nice to get rid of *all* signed integer > overflows and kill the compiler option from Makefile. Therefore the > fixes are indeed very valid in upstream. I actually think the option is unconditionally good. Undefined behaviour in a language is bad. Sadly C has lots of it, but any reduction we can have we must take.