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 3AD4DC433EF for ; Fri, 26 Nov 2021 16:12:54 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1378387AbhKZQQF (ORCPT ); Fri, 26 Nov 2021 11:16:05 -0500 Received: from pegase2.c-s.fr ([93.17.235.10]:53781 "EHLO pegase2.c-s.fr" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1354425AbhKZQOB (ORCPT ); Fri, 26 Nov 2021 11:14:01 -0500 Received: from localhost (mailhub3.si.c-s.fr [172.26.127.67]) by localhost (Postfix) with ESMTP id 4J108l2YfHz9sSM; Fri, 26 Nov 2021 17:10:47 +0100 (CET) X-Virus-Scanned: amavisd-new at c-s.fr Received: from pegase2.c-s.fr ([172.26.127.65]) by localhost (pegase2.c-s.fr [127.0.0.1]) (amavisd-new, port 10024) with ESMTP id k7gFLdaq-XHi; Fri, 26 Nov 2021 17:10:47 +0100 (CET) Received: from messagerie.si.c-s.fr (messagerie.si.c-s.fr [192.168.25.192]) by pegase2.c-s.fr (Postfix) with ESMTP id 4J108l1pGXz9sSL; Fri, 26 Nov 2021 17:10:47 +0100 (CET) Received: from localhost (localhost [127.0.0.1]) by messagerie.si.c-s.fr (Postfix) with ESMTP id 2EFE28B781; Fri, 26 Nov 2021 17:10:47 +0100 (CET) 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 ttGKRtCaua7U; Fri, 26 Nov 2021 17:10:47 +0100 (CET) Received: from [192.168.204.6] (unknown [192.168.204.6]) by messagerie.si.c-s.fr (Postfix) with ESMTP id ABD9E8B763; Fri, 26 Nov 2021 17:10:46 +0100 (CET) Message-ID: <39ec092d-428c-7fce-7291-a88a4caf8b9f@csgroup.eu> Date: Fri, 26 Nov 2021 17:10:46 +0100 MIME-Version: 1.0 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:91.0) Gecko/20100101 Thunderbird/91.3.0 Subject: Re: [PATCH] w1: Misuse of get_user()/put_user() reported by sparse Content-Language: fr-FR To: Greg Kroah-Hartman Cc: Evgeniy Polyakov , linux-kernel@vger.kernel.org, linuxppc-dev@lists.ozlabs.org, kernel test robot References: <2163689da6544c289254b3c69848acc36db998f5.1637313047.git.christophe.leroy@csgroup.eu> From: Christophe Leroy In-Reply-To: Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 8bit Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Le 26/11/2021 à 17:00, Greg Kroah-Hartman a écrit : > On Fri, Nov 19, 2021 at 10:15:09AM +0100, Christophe Leroy wrote: >> sparse warnings: (new ones prefixed by >>) >>>> drivers/w1/slaves/w1_ds28e04.c:342:13: sparse: sparse: incorrect type in initializer (different address spaces) @@ expected char [noderef] __user *_pu_addr @@ got char *buf @@ >> drivers/w1/slaves/w1_ds28e04.c:342:13: sparse: expected char [noderef] __user *_pu_addr >> drivers/w1/slaves/w1_ds28e04.c:342:13: sparse: got char *buf >>>> drivers/w1/slaves/w1_ds28e04.c:356:13: sparse: sparse: incorrect type in initializer (different address spaces) @@ expected char const [noderef] __user *_gu_addr @@ got char const *buf @@ >> drivers/w1/slaves/w1_ds28e04.c:356:13: sparse: expected char const [noderef] __user *_gu_addr >> drivers/w1/slaves/w1_ds28e04.c:356:13: sparse: got char const *buf >> >> The buffer buf is a failsafe buffer in kernel space, it's not user >> memory hence doesn't deserve the use of get_user() or put_user(). >> >> Access 'buf' content directly. >> >> Reported-by: kernel test robot >> Link: https://lore.kernel.org/lkml/202111190526.K5vb7NWC-lkp@intel.com/T/ >> Signed-off-by: Christophe Leroy >> --- >> drivers/w1/slaves/w1_ds28e04.c | 10 ++-------- >> 1 file changed, 2 insertions(+), 8 deletions(-) >> >> diff --git a/drivers/w1/slaves/w1_ds28e04.c b/drivers/w1/slaves/w1_ds28e04.c >> index e4f336111edc..d75bb16fb7a1 100644 >> --- a/drivers/w1/slaves/w1_ds28e04.c >> +++ b/drivers/w1/slaves/w1_ds28e04.c >> @@ -339,10 +339,7 @@ static BIN_ATTR_RW(pio, 1); >> static ssize_t crccheck_show(struct device *dev, struct device_attribute *attr, >> char *buf) >> { >> - if (put_user(w1_enable_crccheck + 0x30, buf)) >> - return -EFAULT; >> - >> - return sizeof(w1_enable_crccheck); >> + return sprintf(buf, "%d", w1_enable_crccheck); > > This should be sysfs_emit(), right? Ok > >> } >> >> static ssize_t crccheck_store(struct device *dev, struct device_attribute *attr, >> @@ -353,11 +350,8 @@ static ssize_t crccheck_store(struct device *dev, struct device_attribute *attr, >> if (count != 1 || !buf) >> return -EINVAL; >> >> - if (get_user(val, buf)) >> - return -EFAULT; >> - >> /* convert to decimal */ >> - val = val - 0x30; >> + val = *buf - 0x30; > > Why not use a proper function that can parse a string and turn it into a > number? I wanted to keep the change minimal. But I can also replace it with some scanf. But don't we have any generic function to read and store a bool after all ? Thanks Christophe