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=-11.5 required=3.0 tests=BAYES_00, HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY, SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED,USER_AGENT_SANE_1 autolearn=unavailable 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 ECA4CC433E2 for ; Thu, 3 Sep 2020 15:57:18 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id D79A0208B3 for ; Thu, 3 Sep 2020 15:57:18 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1728344AbgICP5C (ORCPT ); Thu, 3 Sep 2020 11:57:02 -0400 Received: from verein.lst.de ([213.95.11.211]:38410 "EHLO verein.lst.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1728354AbgICP4s (ORCPT ); Thu, 3 Sep 2020 11:56:48 -0400 Received: by verein.lst.de (Postfix, from userid 2407) id 953B667357; Thu, 3 Sep 2020 17:56:44 +0200 (CEST) Date: Thu, 3 Sep 2020 17:56:44 +0200 From: Christoph Hellwig To: Christophe Leroy Cc: Christoph Hellwig , Linus Torvalds , Al Viro , Michael Ellerman , x86@kernel.org, linux-arch@vger.kernel.org, Kees Cook , linux-kernel@vger.kernel.org, Luis Chamberlain , linux-fsdevel@vger.kernel.org, linuxppc-dev@lists.ozlabs.org, Alexey Dobriyan Subject: Re: [PATCH 14/14] powerpc: remove address space overrides using set_fs() Message-ID: <20200903155644.GA23521@lst.de> References: <20200903142242.925828-1-hch@lst.de> <20200903142242.925828-15-hch@lst.de> <20200903154909.GA23023@lst.de> MIME-Version: 1.0 Content-Type: text/plain; charset=iso-8859-1 Content-Disposition: inline Content-Transfer-Encoding: 8bit In-Reply-To: <20200903154909.GA23023@lst.de> User-Agent: Mutt/1.5.17 (2007-11-01) Sender: linux-fsdevel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-fsdevel@vger.kernel.org On Thu, Sep 03, 2020 at 05:49:09PM +0200, Christoph Hellwig wrote: > On Thu, Sep 03, 2020 at 05:43:25PM +0200, Christophe Leroy wrote: > > > > > > Le 03/09/2020 à 16:22, Christoph Hellwig a écrit : > >> Stop providing the possibility to override the address space using > >> set_fs() now that there is no need for that any more. > >> > >> Signed-off-by: Christoph Hellwig > >> --- > > > > > >> -static inline int __access_ok(unsigned long addr, unsigned long size, > >> - mm_segment_t seg) > >> +static inline bool __access_ok(unsigned long addr, unsigned long size) > >> { > >> - if (addr > seg.seg) > >> - return 0; > >> - return (size == 0 || size - 1 <= seg.seg - addr); > >> + if (addr >= TASK_SIZE_MAX) > >> + return false; > >> + return size == 0 || size <= TASK_SIZE_MAX - addr; > >> } > > > > You don't need to test size == 0 anymore. It used to be necessary because > > of the 'size - 1', as size is unsigned. > > > > Now you can directly do > > > > return size <= TASK_SIZE_MAX - addr; > > > > If size is 0, this will always be true (because you already know that addr > > is not >= TASK_SIZE_MAX > > True. What do you think of Linus' comment about always using the > ppc32 version on ppc64 as well with this? i.e. something like this folded in: diff --git a/arch/powerpc/include/asm/uaccess.h b/arch/powerpc/include/asm/uaccess.h index 5363f7fc6dd06c..be070254e50943 100644 --- a/arch/powerpc/include/asm/uaccess.h +++ b/arch/powerpc/include/asm/uaccess.h @@ -11,26 +11,14 @@ #ifdef __powerpc64__ /* We use TASK_SIZE_USER64 as TASK_SIZE is not constant */ #define TASK_SIZE_MAX TASK_SIZE_USER64 - -/* - * This check is sufficient because there is a large enough gap between user - * addresses and the kernel addresses. - */ -static inline bool __access_ok(unsigned long addr, unsigned long size) -{ - return addr < TASK_SIZE_MAX && size < TASK_SIZE_MAX; -} - #else #define TASK_SIZE_MAX TASK_SIZE +#endif static inline bool __access_ok(unsigned long addr, unsigned long size) { - if (addr >= TASK_SIZE_MAX) - return false; - return size == 0 || size <= TASK_SIZE_MAX - addr; + return addr < TASK_SIZE_MAX && size <= TASK_SIZE_MAX - addr; } -#endif /* __powerpc64__ */ #define access_ok(addr, size) \ (__chk_user_ptr(addr), \