Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S261172AbVA0Ufl (ORCPT ); Thu, 27 Jan 2005 15:35:41 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S261176AbVA0Ufl (ORCPT ); Thu, 27 Jan 2005 15:35:41 -0500 Received: from canuck.infradead.org ([205.233.218.70]:44048 "EHLO canuck.infradead.org") by vger.kernel.org with ESMTP id S261172AbVA0Ufc (ORCPT ); Thu, 27 Jan 2005 15:35:32 -0500 Subject: Re: Patch 4/6 randomize the stack pointer From: Arjan van de Ven To: Christoph Hellwig Cc: linux-kernel@vger.kernel.org, akpm@osdl.org, torvalds@osdl.org In-Reply-To: <20050127203206.GA2180@infradead.org> References: <20050127101117.GA9760@infradead.org> <20050127101322.GE9760@infradead.org> <20050127202335.GA2033@infradead.org> <20050127202720.GA12390@infradead.org> <20050127203206.GA2180@infradead.org> Content-Type: text/plain Date: Thu, 27 Jan 2005 21:35:26 +0100 Message-Id: <1106858127.5624.136.camel@laptopd505.fenrus.org> Mime-Version: 1.0 X-Mailer: Evolution 2.0.2 (2.0.2-3) Content-Transfer-Encoding: 7bit X-Spam-Score: 4.1 (++++) X-Spam-Report: SpamAssassin version 2.63 on canuck.infradead.org summary: Content analysis details: (4.1 points, 5.0 required) pts rule name description ---- ---------------------- -------------------------------------------------- 0.3 RCVD_NUMERIC_HELO Received: contains a numeric HELO 1.1 RCVD_IN_DSBL RBL: Received via a relay in list.dsbl.org [] 2.5 RCVD_IN_DYNABLOCK RBL: Sent directly from dynamic IP address [80.57.133.107 listed in dnsbl.sorbs.net] 0.1 RCVD_IN_SORBS RBL: SORBS: sender is listed in SORBS [80.57.133.107 listed in dnsbl.sorbs.net] X-SRS-Rewrite: SMTP reverse-path rewritten from by canuck.infradead.org See http://www.infradead.org/rpr.html Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1037 Lines: 27 On Thu, 2005-01-27 at 20:32 +0000, Christoph Hellwig wrote: > > The patch below replaces the existing 8Kb randomisation of the userspace > > stack pointer (which is currently only done for Hyperthreaded P-IVs) with a > > more general randomisation over a 64Kb range. 64Kb is not a lot, but it's a > > start and once the dust settles we can increase this value to a more > > agressive value. > > Why are we doing this for x86 only, btw? > > > +unsigned long arch_align_stack(unsigned long sp) > > +{ > > + if (randomize_va_space) > > + sp -= ((get_random_int() % 4096) << 4); > > + return sp & ~0xf; > > +} > > this looks like it'd work nicely on all architectures. the problem is that the <<4 is the minimum x86 stack pointer alignment. That value differs per architecture afaics..... - 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/