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 9DEC7C433F5 for ; Fri, 26 Nov 2021 16:26:15 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S239747AbhKZQ31 (ORCPT ); Fri, 26 Nov 2021 11:29:27 -0500 Received: from dfw.source.kernel.org ([139.178.84.217]:39036 "EHLO dfw.source.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S234731AbhKZQ10 (ORCPT ); Fri, 26 Nov 2021 11:27:26 -0500 Received: from smtp.kernel.org (relay.kernel.org [52.25.139.140]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by dfw.source.kernel.org (Postfix) with ESMTPS id 3A5FA622E2 for ; Fri, 26 Nov 2021 16:24:13 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id 11490C93056; Fri, 26 Nov 2021 16:24:11 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1637943852; bh=Vgi66QN9GrkmxWdokZZIUkz1w8SHaCVhZ2xKywc0LJk=; h=Date:From:To:Cc:Subject:References:In-Reply-To:From; b=t4bsyMz9sZ5SdNFbi8Lg+l0uMiN0ey9VkB0gZ4ewsPhDJKphrgo30OqgVl+Ib/hSy EnbF/tBud01uOKhBFfvaP88G5aI3yq4HPJp0GGxo5Vtv1vKTxg1DuYkD9aCYf+8qDc rMmxt6KmHuJFNfdoWl/FJDeKrEaiClZLjGWxbUyk= Date: Fri, 26 Nov 2021 17:24:09 +0100 From: Greg Kroah-Hartman To: Christophe Leroy Cc: Evgeniy Polyakov , linux-kernel@vger.kernel.org, linuxppc-dev@lists.ozlabs.org, kernel test robot Subject: Re: [PATCH] w1: Misuse of get_user()/put_user() reported by sparse Message-ID: References: <2163689da6544c289254b3c69848acc36db998f5.1637313047.git.christophe.leroy@csgroup.eu> <39ec092d-428c-7fce-7291-a88a4caf8b9f@csgroup.eu> MIME-Version: 1.0 Content-Type: text/plain; charset=iso-8859-1 Content-Disposition: inline Content-Transfer-Encoding: 8bit In-Reply-To: <39ec092d-428c-7fce-7291-a88a4caf8b9f@csgroup.eu> Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Fri, Nov 26, 2021 at 05:10:46PM +0100, Christophe Leroy wrote: > > > 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 ? Yes we do, please use kstrtobool(). thanks, greg k-h