Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S932105AbbERNCX (ORCPT ); Mon, 18 May 2015 09:02:23 -0400 Received: from atrey.karlin.mff.cuni.cz ([195.113.26.193]:33076 "EHLO atrey.karlin.mff.cuni.cz" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752028AbbERNCR (ORCPT ); Mon, 18 May 2015 09:02:17 -0400 Date: Mon, 18 May 2015 15:02:13 +0200 From: Pavel Machek To: Anisse Astier Cc: Andrew Morton , Mel Gorman , "Kirill A. Shutemov" , David Rientjes , Alan Cox , Linus Torvalds , Peter Zijlstra , PaX Team , Brad Spengler , Kees Cook , Andi Kleen , "Rafael J. Wysocki" , Len Brown , linux-mm@kvack.org, Linux PM list , Linux Kernel Mailing List Subject: Re: [PATCH v4 2/3] mm/page_alloc.c: add config option to sanitize freed pages Message-ID: <20150518130213.GA771@amd> References: <1431613188-4511-1-git-send-email-anisse@astier.eu> <1431613188-4511-3-git-send-email-anisse@astier.eu> <20150518112152.GA16999@amd> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: User-Agent: Mutt/1.5.23 (2014-03-12) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1674 Lines: 37 On Mon 2015-05-18 14:41:19, Anisse Astier wrote: > On Mon, May 18, 2015 at 1:21 PM, Pavel Machek wrote: > > On Thu 2015-05-14 16:19:47, Anisse Astier wrote: > >> This new config option will sanitize all freed pages. This is a pretty > >> low-level change useful to track some cases of use-after-free, help > >> kernel same-page merging in VM environments, and counter a few info > >> leaks. > > > > Could you document the "few info leaks"? We may want to fix them for > > !SANTIZE_FREED_PAGES case, too... > > > > I wish I could; I'd be sending patches for those info leaks, too. > > What I meant is that this feature can also be used as a general > protection mechanism against a certain class of info leaks; for > example, some drivers allocating pages that were previously used by > other subsystems, and then sending structures to userspace that > contain padding or uninitialized fields, leaking kernel pointers. > Having all pages cleared unconditionally can help a bit in some cases > (hence "a few"), but it's of course not an end-all solution. Ok. So there is class of errors where this helps, but you are not aware of any such errors in kernel, so you can't fix them... Right? > I'll edit the commit and kconfig messages to be more precise. Thanks, 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/