Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S938814AbXFHPMR (ORCPT ); Fri, 8 Jun 2007 11:12:17 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S938322AbXFHPLS (ORCPT ); Fri, 8 Jun 2007 11:11:18 -0400 Received: from gprs189-60.eurotel.cz ([160.218.189.60]:2730 "EHLO spitz.ucw.cz" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1756645AbXFHPLR (ORCPT ); Fri, 8 Jun 2007 11:11:17 -0400 Date: Thu, 7 Jun 2007 14:28:02 +0000 From: Pavel Machek To: "H. Peter Anvin" Cc: Eric Paris , Alan Cox , James Morris , linux-kernel@vger.kernel.org, selinux@tycho.nsa.gov, drepper@redhat.com, roland@redhat.com, arjan@infradead.org, mingo@elte.hu, viro@zeniv.linux.org.uk, chrisw@redhat.com, sds@tycho.nsa.gov, sgrubb@redhat.com Subject: Re: [PATCH] Protection for exploiting null dereference using mmap Message-ID: <20070607142802.GB9094@ucw.cz> References: <1180561713.3633.27.camel@dhcp231-215.rdu.redhat.com> <20070603205653.GE25869@devserv.devel.redhat.com> <1180964306.14220.34.camel@moss-spartans.epoch.ncsc.mil> <1181075666.3978.31.camel@localhost.localdomain> <20070605211616.GE23291@devserv.devel.redhat.com> <1181078927.3978.42.camel@localhost.localdomain> <4665E7CA.8030907@zytor.com> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <4665E7CA.8030907@zytor.com> User-Agent: Mutt/1.5.9i Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1278 Lines: 31 Hi! > > While I understand, there are a few users who will have problems with > > this default are we really better to not provide this defense in depth > > for the majority of users and let those with problems turn it off rather > > than provide no defense by default? I could even provide a different > > default for SELinux and non-SELinux if anyone saw value in that? But if > > others think that off default is best I'll send another patch shortly > > with the unsigned long fix and the default set to 0. My hope is then > > that distros will figure out to turn this on. > > > > I hope not. This breaks any hardware virtualizer. > > So yes, we're better off not having this on, and require it to be > explicitly enabled by the end user. You could do something like 4G+4G patches.... but performance penalty would be ugly. But no, we cant break userspace 'by default'. Pavel -- (english) http://www.livejournal.com/~pavelmachek (cesky, pictures) http://atrey.karlin.mff.cuni.cz/~pavel/picture/horses/blog.html - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/