Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754127AbbEMJwL (ORCPT ); Wed, 13 May 2015 05:52:11 -0400 Received: from r00tworld.com ([212.85.137.150]:58375 "EHLO r00tworld.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751418AbbEMJwH (ORCPT ); Wed, 13 May 2015 05:52:07 -0400 From: "PaX Team" To: Pavel Machek , Anisse Astier Date: Wed, 13 May 2015 11:50:20 +0200 MIME-Version: 1.0 Subject: Re: [PATCH v3 2/4] PM / Hibernate: prepare for SANITIZE_FREED_PAGES Reply-to: pageexec@freemail.hu CC: Andrew Morton , Mel Gorman , "Kirill A. Shutemov" , David Rientjes , Alan Cox , Linus Torvalds , Peter Zijlstra , Brad Spengler , Kees Cook , Andi Kleen , "Rafael J. Wysocki" , Len Brown , linux-mm@kvack.org, Linux PM list , Linux Kernel Mailing List , Mathias Krause Message-ID: <55531E5C.32539.21B688F@pageexec.freemail.hu> In-reply-to: References: <1430980452-2767-1-git-send-email-anisse@astier.eu>, <20150509154455.GA32002@amd>, X-mailer: Pegasus Mail for Windows (4.70) Content-type: text/plain; charset=US-ASCII Content-transfer-encoding: 7BIT Content-description: Mail message body X-Greylist: Sender IP whitelisted, not delayed by milter-greylist-2.1.12 (r00tworld.com [212.85.137.150]); Wed, 13 May 2015 11:50:24 +0200 (CEST) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1397 Lines: 29 On 11 May 2015 at 9:59, Anisse Astier wrote: > > Otherwise it looks good to me... if the sanitization is considered > > useful. Did it catch some bugs in the past? > > > > I've read somewhere that users of grsecurity claim that it caught bugs > in some drivers, but I haven't verified that personally; it's probably > much less useful than kasan (or even the original grsec feature) as a > bug-catcher since it doesn't clear freed slab buffers. the PaX SANITIZE feature wasn't developed for catching use-after-free bugs but to help reduce data lifetime from the kernel while not killing too much performance (this is why i was reluctant to add a finer grained version to do slab object sanitization until Mathias Krause came up with a workable compromise). another reason page zeroing isn't good at catching these bugs is that the 0 fill value will produce NULL pointers which are often explicitly handled already. on the other hand changing the fill value would not allow the __GFP_ZERO performance optimization (the slab sanitization feature is a different story however, we have a non-0 fill value and it keeps triggering use-after-free bugs). -- 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/