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 X-Spam-Level: X-Spam-Status: No, score=-8.5 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_PASS,USER_AGENT_MUTT autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id CD7D5C43219 for ; Fri, 3 May 2019 16:56:58 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 9C926206C3 for ; Fri, 3 May 2019 16:56:58 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1728660AbfECQ45 (ORCPT ); Fri, 3 May 2019 12:56:57 -0400 Received: from usa-sjc-mx-foss1.foss.arm.com ([217.140.101.70]:37192 "EHLO foss.arm.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1728637AbfECQ45 (ORCPT ); Fri, 3 May 2019 12:56:57 -0400 Received: from usa-sjc-imap-foss1.foss.arm.com (unknown [10.72.51.249]) by usa-sjc-mx-foss1.foss.arm.com (Postfix) with ESMTP id 091DE15A2; Fri, 3 May 2019 09:56:56 -0700 (PDT) Received: from arrakis.emea.arm.com (arrakis.cambridge.arm.com [10.1.196.78]) by usa-sjc-imap-foss1.foss.arm.com (Postfix) with ESMTPSA id 7F2813F557; Fri, 3 May 2019 09:56:49 -0700 (PDT) Date: Fri, 3 May 2019 17:56:46 +0100 From: Catalin Marinas To: Andrey Konovalov Cc: linux-arm-kernel@lists.infradead.org, linux-mm@kvack.org, linux-kernel@vger.kernel.org, amd-gfx@lists.freedesktop.org, dri-devel@lists.freedesktop.org, linux-rdma@vger.kernel.org, linux-media@vger.kernel.org, kvm@vger.kernel.org, linux-kselftest@vger.kernel.org, Vincenzo Frascino , Will Deacon , Mark Rutland , Andrew Morton , Greg Kroah-Hartman , Kees Cook , Yishai Hadas , Kuehling@google.com, Felix , Deucher@google.com, Alexander , Koenig@google.com, Christian , Mauro Carvalho Chehab , Jens Wiklander , Alex Williamson , Leon Romanovsky , Dmitry Vyukov , Kostya Serebryany , Evgeniy Stepanov , Lee Smith , Ramana Radhakrishnan , Jacob Bramley , Ruben Ayrapetyan , Robin Murphy , Chintan Pandya , Luc Van Oostenryck , Dave Martin , Kevin Brodsky , Szabolcs Nagy Subject: Re: [PATCH v14 10/17] fs, arm64: untag user pointers in fs/userfaultfd.c Message-ID: <20190503165646.GK55449@arrakis.emea.arm.com> References: <7d3b28689d47c0fa1b80628f248dbf78548da25f.1556630205.git.andreyknvl@google.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <7d3b28689d47c0fa1b80628f248dbf78548da25f.1556630205.git.andreyknvl@google.com> User-Agent: Mutt/1.10.1 (2018-07-13) Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Tue, Apr 30, 2019 at 03:25:06PM +0200, Andrey Konovalov wrote: > This patch is a part of a series that extends arm64 kernel ABI to allow to > pass tagged user pointers (with the top byte set to something else other > than 0x00) as syscall arguments. > > userfaultfd_register() and userfaultfd_unregister() use provided user > pointers for vma lookups, which can only by done with untagged pointers. > > Untag user pointers in these functions. > > Signed-off-by: Andrey Konovalov > --- > fs/userfaultfd.c | 5 +++++ > 1 file changed, 5 insertions(+) > > diff --git a/fs/userfaultfd.c b/fs/userfaultfd.c > index f5de1e726356..fdee0db0e847 100644 > --- a/fs/userfaultfd.c > +++ b/fs/userfaultfd.c > @@ -1325,6 +1325,9 @@ static int userfaultfd_register(struct userfaultfd_ctx *ctx, > goto out; > } > > + uffdio_register.range.start = > + untagged_addr(uffdio_register.range.start); > + > ret = validate_range(mm, uffdio_register.range.start, > uffdio_register.range.len); > if (ret) > @@ -1514,6 +1517,8 @@ static int userfaultfd_unregister(struct userfaultfd_ctx *ctx, > if (copy_from_user(&uffdio_unregister, buf, sizeof(uffdio_unregister))) > goto out; > > + uffdio_unregister.start = untagged_addr(uffdio_unregister.start); > + > ret = validate_range(mm, uffdio_unregister.start, > uffdio_unregister.len); > if (ret) Wouldn't it be easier to do this in validate_range()? There are a few more calls in this file, though I didn't check whether a tagged address would cause issues. -- Catalin