From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1755043AbbIXQsg (ORCPT ); Thu, 24 Sep 2015 12:48:36 -0400 Received: from mail.skyhub.de ([78.46.96.112]:52625 "EHLO mail.skyhub.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752805AbbIXQse (ORCPT ); Thu, 24 Sep 2015 12:48:34 -0400 Date: Thu, 24 Sep 2015 18:48:30 +0200 From: Borislav Petkov To: Toshi Kani Cc: mchehab@osg.samsung.com, dougthompson@xmission.com, linux-edac@vger.kernel.org, linux-kernel@vger.kernel.org, elliott@hpe.com, tony.luck@intel.com Subject: Re: [PATCH v2 2/2] EDAC: Fix sysfs dimm_label store operation Message-ID: <20150924164830.GF3774@pd.tnic> References: <1442933883-21587-1-git-send-email-toshi.kani@hpe.com> <1442933883-21587-3-git-send-email-toshi.kani@hpe.com> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline In-Reply-To: <1442933883-21587-3-git-send-email-toshi.kani@hpe.com> User-Agent: Mutt/1.5.23 (2014-03-12) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Tue, Sep 22, 2015 at 08:58:03AM -0600, Toshi Kani wrote: > Sysfs "dimm_label" and "chX_dimm_label" have the following issues > in their store operation. > > 1) A newline-terminated input string causes redundant newlines > > # echo "test" > /sys/bus/mc0/devices/dimm0/dimm_label > # cat /sys/bus/mc0/devices/dimm0/dimm_label > test > > # od -bc /sys/bus/mc0/devices/dimm0/dimm_label > 0000000 164 145 163 164 012 012 > t e s t \n \n > 0000006 > > 2) The original label string (31 characters) cannot be stored due to > an improper size check > > # echo "CPU_SrcID#0_Ha#0_Chan#0_DIMM#0" \ > > /sys/bus/mc0/devices/dimm0/dimm_label > # cat /sys/bus/mc0/devices/dimm0/dimm_label > > > # od -bc /sys/bus/mc0/devices/dimm0/dimm_label > 0000000 012 012 > \n \n > 0000002 > > 3) An input string longer than the buffer size results a wrong label > info as it allows a retry with the remaining string. > > # echo "CPU_SrcID#0_Ha#0_Chan#0_DIMM#0_TEST" \ > > /sys/bus/mc0/devices/dimm0/dimm_label > # cat /sys/bus/mc0/devices/dimm0/dimm_label > _TEST > > Fix these issues by making the following changes: > 1) Replace a newline charactor at the end by setting a null. It also > assures that the string is null-terminated within the size. > 2) Check the label buffer size with 'sizeof(dimm->label)'. > 3) Fail a request if its string exceeds the label buffer size. > > Signed-off-by: Toshi Kani > Acked-by: Tony Luck > Cc: Mauro Carvalho Chehab > Cc: Borislav Petkov > Cc: Doug Thompson > Cc: Robert Elliott > Cc: Tony Luck > --- > drivers/edac/edac_mc_sysfs.c | 20 ++++++++++---------- > 1 file changed, 10 insertions(+), 10 deletions(-) ... > @@ -495,13 +495,13 @@ static ssize_t dimmdev_label_store(struct device *dev, > { > struct dimm_info *dimm = to_dimm(dev); > > - ssize_t max_size = 0; > + if (count == 0 || count > sizeof(dimm->label)) > + return -EINVAL; $ echo "" > /sys/bus/mc0/devices/dimm0/dimm_label $ od -bc /sys/bus/mc0/devices/dimm0/dimm_label 0000000 $ cat /sys/bus/mc0/devices/dimm0/dimm_label $ I don't think we want to allow empty labels. I guess something like this (2 because there's also the additional "\n"): diff --git a/drivers/edac/edac_mc_sysfs.c b/drivers/edac/edac_mc_sysfs.c index d4e0bff268d8..e52ba338334b 100644 --- a/drivers/edac/edac_mc_sysfs.c +++ b/drivers/edac/edac_mc_sysfs.c @@ -241,7 +241,7 @@ static ssize_t channel_dimm_label_store(struct device *dev, unsigned chan = to_channel(mattr); struct rank_info *rank = csrow->channels[chan]; - if (count == 0 || count > sizeof(rank->dimm->label)) + if (count < 2 || count > sizeof(rank->dimm->label)) return -EINVAL; strncpy(rank->dimm->label, data, count); @@ -495,7 +495,7 @@ static ssize_t dimmdev_label_store(struct device *dev, { struct dimm_info *dimm = to_dimm(dev); - if (count == 0 || count > sizeof(dimm->label)) + if (count < 2 || count > sizeof(dimm->label)) return -EINVAL; strncpy(dimm->label, data, count); -- Regards/Gruss, Boris. ECO tip #101: Trim your mails when you reply.