From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 2C5CAC77B7E for ; Fri, 28 Apr 2023 18:28:09 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1346471AbjD1S2H (ORCPT ); Fri, 28 Apr 2023 14:28:07 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:53424 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1346363AbjD1S2F (ORCPT ); Fri, 28 Apr 2023 14:28:05 -0400 Received: from outgoing.mit.edu (outgoing-auth-1.mit.edu [18.9.28.11]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 7506FE7C for ; Fri, 28 Apr 2023 11:28:04 -0700 (PDT) Received: from letrec.thunk.org ([76.150.80.181]) (authenticated bits=0) (User authenticated as tytso@ATHENA.MIT.EDU) by outgoing.mit.edu (8.14.7/8.12.4) with ESMTP id 33SIPsvO024394 (version=TLSv1/SSLv3 cipher=DHE-RSA-AES256-GCM-SHA384 bits=256 verify=NOT); Fri, 28 Apr 2023 14:25:55 -0400 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=mit.edu; s=outgoing; t=1682706363; bh=+QeRTh3Q792/eFaJgfAgGyTYF+cryOwA6A0C+nRVDy8=; h=Date:From:To:Cc:Subject:References:In-Reply-To; b=AMh5xv+jG+n9laJ4e0qLg3l6ymmeae7bAXwqrq4kE8f9OTLDZec1GN/EZ4P11VjB7 r7tdp+zdX1OwYKlDp+K5fMVWj0mHfs68d3QH3Ak6FfD/zOf0HeAfsuD0nOiJBObAD9 oLIceXgN8fEn9ItUp1TEodH8IuHPQm/vCmstG89u0yJfAIVgz+nUoS5GMv0EvyLAy+ wWf7gGYeXDT2RGdrlTOO9RatuD0Rdhg4poRc4X7OvNvkL0Hjb/gtXj+quB83D9R8UX 4Y4y0g9DMWE0P4vfvb8BkRELNhxxIwazgFHVscRWZAnwkhiC8/6hz7tspIL09c5E2/ FI/r3M817jUPA== Received: by letrec.thunk.org (Postfix, from userid 15806) id 164EF8C01E0; Fri, 28 Apr 2023 14:25:53 -0400 (EDT) Date: Fri, 28 Apr 2023 14:25:53 -0400 From: "Theodore Ts'o" To: Jason Gunthorpe Cc: David Hildenbrand , Lorenzo Stoakes , linux-mm@kvack.org, linux-kernel@vger.kernel.org, Andrew Morton , Jens Axboe , Matthew Wilcox , Dennis Dalessandro , Leon Romanovsky , Christian Benvenuti , Nelson Escobar , Bernard Metzler , Peter Zijlstra , Ingo Molnar , Arnaldo Carvalho de Melo , Mark Rutland , Alexander Shishkin , Jiri Olsa , Namhyung Kim , Ian Rogers , Adrian Hunter , Bjorn Topel , Magnus Karlsson , Maciej Fijalkowski , Jonathan Lemon , "David S . Miller" , Eric Dumazet , Jakub Kicinski , Paolo Abeni , Christian Brauner , Richard Cochran , Alexei Starovoitov , Daniel Borkmann , Jesper Dangaard Brouer , John Fastabend , linux-fsdevel@vger.kernel.org, linux-perf-users@vger.kernel.org, netdev@vger.kernel.org, bpf@vger.kernel.org, Oleg Nesterov , John Hubbard , Jan Kara , "Kirill A . Shutemov" , Pavel Begunkov , Mika Penttila , David Howells , Christoph Hellwig Subject: Re: [PATCH v5] mm/gup: disallow GUP writing to file-backed mappings by default Message-ID: References: <6b73e692c2929dc4613af711bdf92e2ec1956a66.1682638385.git.lstoakes@gmail.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: Precedence: bulk List-ID: X-Mailing-List: netdev@vger.kernel.org On Fri, Apr 28, 2023 at 11:35:32AM -0300, Jason Gunthorpe wrote: > > It has been years now, I think we need to admit a fix is still years > away. Blocking the security problem may even motivate more people to > work on a fix. Do we think we can still trigger a kernel crash, or maybe even some more exciting like an arbitrary buffer overrun, via the process_vm_writev(2) system call into a file-backed mmap'ed region? Maybe if someone can come up with an easy-to-expliot security proof of aconcept, that doesn't require special RDMA hardware or some special libvirt setup, we could finally get motivation to get it fixed, or at least blocked? :-) We've only been talking about it for years, after all... - Ted > Security is the primary case where we have historically closed uAPI > items. > > Jason