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 32FA3C433F5 for ; Fri, 26 Nov 2021 17:04:40 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S238830AbhKZRHw (ORCPT ); Fri, 26 Nov 2021 12:07:52 -0500 Received: from ams.source.kernel.org ([145.40.68.75]:41546 "EHLO ams.source.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S231339AbhKZRFv (ORCPT ); Fri, 26 Nov 2021 12:05:51 -0500 X-Greylist: delayed 6451 seconds by postgrey-1.27 at vger.kernel.org; Fri, 26 Nov 2021 12:05:50 EST 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 ams.source.kernel.org (Postfix) with ESMTPS id 33CA0B82857 for ; Fri, 26 Nov 2021 17:02:31 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id 46BDBC93056; Fri, 26 Nov 2021 17:02:29 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1637946149; bh=yuE+BreTQT02yvn8X1u7k+Z03tC9pJONhbHdFlU5fDw=; h=Date:From:To:Cc:Subject:References:In-Reply-To:From; b=GFLbnAlBGzqnesySG38WMS+nG1yJXFvLI/1+fMGUeZqqUIr0EIeDBFs/WIj8Z26dP 6RQEXrEF46kuRe4u9SD0Z5PIxUVKoIsXDGoMe/0L0DswGLOB+/8AlZnTc/J3JWiMfI TEBS/ZopFOFZvVOIj5Q+G3Mmtr8gPDV4b3jgSJ9U= Date: Fri, 26 Nov 2021 18:02:27 +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 v2] w1: Misuse of get_user()/put_user() reported by sparse Message-ID: References: <926b572075a26835f4e39d05710cd1b75fd4d5a4.1637945194.git.christophe.leroy@csgroup.eu> <8e5493ac-dd05-9bad-c9ae-169114e0fdcf@csgroup.eu> MIME-Version: 1.0 Content-Type: text/plain; charset=iso-8859-1 Content-Disposition: inline Content-Transfer-Encoding: 8bit In-Reply-To: <8e5493ac-dd05-9bad-c9ae-169114e0fdcf@csgroup.eu> Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Fri, Nov 26, 2021 at 05:57:58PM +0100, Christophe Leroy wrote: > > > Le 26/11/2021 à 17:54, Greg Kroah-Hartman a écrit : > > On Fri, Nov 26, 2021 at 05:47:58PM +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 > > > --- > > > v2: Use sysfs_emit() and kstrtobool() > > > --- > > > drivers/w1/slaves/w1_ds28e04.c | 25 +++---------------------- > > > 1 file changed, 3 insertions(+), 22 deletions(-) > > > > > > diff --git a/drivers/w1/slaves/w1_ds28e04.c b/drivers/w1/slaves/w1_ds28e04.c > > > index e4f336111edc..98f80f412cfd 100644 > > > --- a/drivers/w1/slaves/w1_ds28e04.c > > > +++ b/drivers/w1/slaves/w1_ds28e04.c > > > @@ -32,7 +32,7 @@ static int w1_strong_pullup = 1; > > > module_param_named(strong_pullup, w1_strong_pullup, int, 0); > > > /* enable/disable CRC checking on DS28E04-100 memory accesses */ > > > -static char w1_enable_crccheck = 1; > > > +static bool w1_enable_crccheck = true; > > > #define W1_EEPROM_SIZE 512 > > > #define W1_PAGE_COUNT 16 > > > @@ -339,32 +339,13 @@ 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 sysfs_emit(buf, "%d\n", w1_enable_crccheck); > > > } > > > static ssize_t crccheck_store(struct device *dev, struct device_attribute *attr, > > > const char *buf, size_t count) > > > { > > > - char val; > > > - > > > - if (count != 1 || !buf) > > > - return -EINVAL; > > > - > > > - if (get_user(val, buf)) > > > - return -EFAULT; > > > - > > > - /* convert to decimal */ > > > - val = val - 0x30; > > > - if (val != 0 && val != 1) > > > - return -EINVAL; > > > - > > > - /* set the new value */ > > > - w1_enable_crccheck = val; > > > - > > > - return sizeof(w1_enable_crccheck); > > > + return kstrtobool(buf, &w1_enable_crccheck) ? : count; > > > > Please spell this line out, using ? : is unreadable at times. > > > > You prefer something like: > > int err = kstrtobool(buf, &w1_enable_crccheck); > > return err ? err : count; > > > Or > > int err = kstrtobool(buf, &w1_enable_crccheck); > > if (err) > return err; > > return count; This one. Write code for people to read first, compiler second. thanks, greg k-h