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=-10.3 required=3.0 tests=BAYES_00, HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_PATCH,MAILING_LIST_MULTI,NICE_REPLY_A, SPF_HELO_NONE,SPF_PASS,USER_AGENT_SANE_1 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 28B03C48BE5 for ; Tue, 15 Jun 2021 07:29:00 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 12221600CD for ; Tue, 15 Jun 2021 07:29:00 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S229788AbhFOHbD (ORCPT ); Tue, 15 Jun 2021 03:31:03 -0400 Received: from pegase1.c-s.fr ([93.17.236.30]:11663 "EHLO pegase1.c-s.fr" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229908AbhFOHbC (ORCPT ); Tue, 15 Jun 2021 03:31:02 -0400 Received: from localhost (mailhub3.si.c-s.fr [192.168.12.233]) by localhost (Postfix) with ESMTP id 4G40LK5WyBzBBQy; Tue, 15 Jun 2021 09:28:57 +0200 (CEST) X-Virus-Scanned: amavisd-new at c-s.fr Received: from pegase1.c-s.fr ([192.168.12.234]) by localhost (pegase1.c-s.fr [127.0.0.1]) (amavisd-new, port 10024) with ESMTP id utAMxQNL3e0X; Tue, 15 Jun 2021 09:28:57 +0200 (CEST) Received: from messagerie.si.c-s.fr (messagerie.si.c-s.fr [192.168.25.192]) by pegase1.c-s.fr (Postfix) with ESMTP id 4G40LK2Q82zBBDH; Tue, 15 Jun 2021 09:28:57 +0200 (CEST) Received: from localhost (localhost [127.0.0.1]) by messagerie.si.c-s.fr (Postfix) with ESMTP id 364218B7A3; Tue, 15 Jun 2021 09:28:57 +0200 (CEST) X-Virus-Scanned: amavisd-new at c-s.fr Received: from messagerie.si.c-s.fr ([127.0.0.1]) by localhost (messagerie.si.c-s.fr [127.0.0.1]) (amavisd-new, port 10023) with ESMTP id HMyoXwMPJYV4; Tue, 15 Jun 2021 09:28:57 +0200 (CEST) Received: from [192.168.4.90] (unknown [192.168.4.90]) by messagerie.si.c-s.fr (Postfix) with ESMTP id BFA318B7A2; Tue, 15 Jun 2021 09:28:56 +0200 (CEST) Subject: Re: [PATCH 5/7] signal: Add unsafe_copy_siginfo_to_user() To: Christoph Hellwig Cc: Benjamin Herrenschmidt , Paul Mackerras , Michael Ellerman , linux-arch@vger.kernel.org, linuxppc-dev@lists.ozlabs.org, linux-kernel@vger.kernel.org References: <684939dcfef612fac573d1b983a977215b71f64d.1623739212.git.christophe.leroy@csgroup.eu> <7061fbee-cc82-2699-cf12-e5a4ae46940f@csgroup.eu> From: Christophe Leroy Message-ID: Date: Tue, 15 Jun 2021 09:28:54 +0200 User-Agent: Mozilla/5.0 (Windows NT 6.1; Win64; x64; rv:78.0) Gecko/20100101 Thunderbird/78.11.0 MIME-Version: 1.0 In-Reply-To: Content-Type: text/plain; charset=utf-8; format=flowed Content-Language: fr Content-Transfer-Encoding: 8bit Precedence: bulk List-ID: X-Mailing-List: linux-arch@vger.kernel.org Le 15/06/2021 à 09:21, Christoph Hellwig a écrit : > On Tue, Jun 15, 2021 at 09:03:42AM +0200, Christophe Leroy wrote: >> >> >> Le 15/06/2021 ?? 08:52, Christoph Hellwig a ??crit??: >>> On Tue, Jun 15, 2021 at 06:41:01AM +0000, Christophe Leroy wrote: >>>> + unsafe_copy_to_user(__ucs_to, __ucs_from, \ >>>> + sizeof(struct kernel_siginfo), label); \ >>>> + unsafe_clear_user(__ucs_expansion, SI_EXPANSION_SIZE, label); \ >>>> +} while (0) >>> >>> unsafe_clear_user does not exist at this point, and even your later >>> patch only adds it for powerpc. >>> >> >> You missed below chunck I guess: >> >>> diff --git a/include/linux/uaccess.h b/include/linux/uaccess.h >>> index c05e903cef02..37073caac474 100644 >>> --- a/include/linux/uaccess.h >>> +++ b/include/linux/uaccess.h >>> @@ -398,6 +398,7 @@ long strnlen_user_nofault(const void __user *unsafe_addr, long count); >>> #define unsafe_put_user(x,p,e) unsafe_op_wrap(__put_user(x,p),e) >>> #define unsafe_copy_to_user(d,s,l,e) unsafe_op_wrap(__copy_to_user(d,s,l),e) >>> #define unsafe_copy_from_user(d,s,l,e) unsafe_op_wrap(__copy_from_user(d,s,l),e) >>> +#define unsafe_clear_user(d, l, e) unsafe_op_wrap(__clear_user(d, l), e) > > That doesn't help with architectures that define user_access_begin but > do not define unsafe_clear_user. (i.e. x86). > Yes, the day they want to use unsafe_copy_siginfo_to_user() they'll have to implement unsafe_clear_user(). Until that day, they don't need unsafe_clear_user() and I'm sure the result would be disastrous if a poor powerpc guy like me was trying to implement some low level x86 code. Similar to unsafe_get_compat_sigset(), an arch wanting to use it has to implement unsafe_copy_from_user().