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=-6.8 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS 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 1CB5AC31E46 for ; Wed, 12 Jun 2019 14:33:47 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id F186D2082C for ; Wed, 12 Jun 2019 14:33:46 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726881AbfFLOdq (ORCPT ); Wed, 12 Jun 2019 10:33:46 -0400 Received: from foss.arm.com ([217.140.110.172]:54532 "EHLO foss.arm.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726840AbfFLOdq (ORCPT ); Wed, 12 Jun 2019 10:33:46 -0400 Received: from usa-sjc-imap-foss1.foss.arm.com (unknown [10.121.207.14]) by usa-sjc-mx-foss1.foss.arm.com (Postfix) with ESMTP id 38A462B; Wed, 12 Jun 2019 07:33:45 -0700 (PDT) Received: from [10.1.196.72] (e119884-lin.cambridge.arm.com [10.1.196.72]) by usa-sjc-imap-foss1.foss.arm.com (Postfix) with ESMTPSA id C1F953F557; Wed, 12 Jun 2019 07:33:39 -0700 (PDT) Subject: Re: [PATCH v17 05/15] mm, arm64: untag user pointers in mm/gup.c To: Andrey Konovalov , 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 Cc: Catalin Marinas , Will Deacon , Mark Rutland , Andrew Morton , Greg Kroah-Hartman , Kees Cook , Yishai Hadas , Felix Kuehling , Alexander Deucher , Christian Koenig , Mauro Carvalho Chehab , Jens Wiklander , Alex Williamson , Leon Romanovsky , Luc Van Oostenryck , Dave Martin , Khalid Aziz , enh , Jason Gunthorpe , Christoph Hellwig , Dmitry Vyukov , Kostya Serebryany , Evgeniy Stepanov , Lee Smith , Ramana Radhakrishnan , Jacob Bramley , Ruben Ayrapetyan , Robin Murphy , Kevin Brodsky , Szabolcs Nagy References: <8f65548bef8544d49980a92d221b74440d544c1e.1560339705.git.andreyknvl@google.com> From: Vincenzo Frascino Message-ID: <8b74a24e-4fe0-3fdd-e66a-d04c359b6104@arm.com> Date: Wed, 12 Jun 2019 15:33:38 +0100 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:60.0) Gecko/20100101 Thunderbird/60.6.1 MIME-Version: 1.0 In-Reply-To: <8f65548bef8544d49980a92d221b74440d544c1e.1560339705.git.andreyknvl@google.com> Content-Type: text/plain; charset=utf-8 Content-Language: en-US Content-Transfer-Encoding: 7bit Sender: linux-kselftest-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kselftest@vger.kernel.org On 12/06/2019 12:43, 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. > > mm/gup.c provides a kernel interface that accepts user addresses and > manipulates user pages directly (for example get_user_pages, that is used > by the futex syscall). Since a user can provided tagged addresses, we need > to handle this case. > > Add untagging to gup.c functions that use user addresses for vma lookups. > > Reviewed-by: Kees Cook > Reviewed-by: Catalin Marinas > Signed-off-by: Andrey Konovalov Reviewed-by: Vincenzo Frascino > --- > mm/gup.c | 4 ++++ > 1 file changed, 4 insertions(+) > > diff --git a/mm/gup.c b/mm/gup.c > index ddde097cf9e4..c37df3d455a2 100644 > --- a/mm/gup.c > +++ b/mm/gup.c > @@ -802,6 +802,8 @@ static long __get_user_pages(struct task_struct *tsk, struct mm_struct *mm, > if (!nr_pages) > return 0; > > + start = untagged_addr(start); > + > VM_BUG_ON(!!pages != !!(gup_flags & FOLL_GET)); > > /* > @@ -964,6 +966,8 @@ int fixup_user_fault(struct task_struct *tsk, struct mm_struct *mm, > struct vm_area_struct *vma; > vm_fault_t ret, major = 0; > > + address = untagged_addr(address); > + > if (unlocked) > fault_flags |= FAULT_FLAG_ALLOW_RETRY; > > -- Regards, Vincenzo