From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751897Ab3J3HbL (ORCPT ); Wed, 30 Oct 2013 03:31:11 -0400 Received: from mga14.intel.com ([143.182.124.37]:65264 "EHLO mga14.intel.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751287Ab3J3HbK convert rfc822-to-8bit (ORCPT ); Wed, 30 Oct 2013 03:31:10 -0400 X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="4.93,599,1378882800"; d="scan'208";a="419555665" From: "Winkler, Tomas" To: Greg KH CC: "arnd@arndb.de" , "linux-kernel@vger.kernel.org" Subject: RE: [char-misc-next 2/8] mei: hbm: validate client index is not exceeding allocated array size Thread-Topic: [char-misc-next 2/8] mei: hbm: validate client index is not exceeding allocated array size Thread-Index: AQHO1P1fK4LeAfMsSUaVHro4fls3UJoM14aw Date: Wed, 30 Oct 2013 07:31:06 +0000 Message-ID: <5B8DA87D05A7694D9FA63FD143655C1B1AEFB95D@HASMSX106.ger.corp.intel.com> References: <1382382343-12066-1-git-send-email-tomas.winkler@intel.com> <1382382343-12066-3-git-send-email-tomas.winkler@intel.com> <20131029231945.GB30410@kroah.com> In-Reply-To: <20131029231945.GB30410@kroah.com> Accept-Language: en-US Content-Language: en-US X-MS-Has-Attach: X-MS-TNEF-Correlator: x-originating-ip: [10.184.70.12] Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 8BIT MIME-Version: 1.0 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org > > --- > > drivers/misc/mei/hbm.c | 6 ++++-- > > 1 file changed, 4 insertions(+), 2 deletions(-) > > > > diff --git a/drivers/misc/mei/hbm.c b/drivers/misc/mei/hbm.c > > index 9b3a0fb..0f5e8ca 100644 > > --- a/drivers/misc/mei/hbm.c > > +++ b/drivers/misc/mei/hbm.c > > @@ -228,8 +228,6 @@ static int mei_hbm_prop_req(struct mei_device *dev) > > unsigned long client_num; > > > > > > - client_num = dev->me_client_presentation_num; > > - > > next_client_index = find_next_bit(dev->me_clients_map, > MEI_CLIENTS_MAX, > > dev->me_client_index); > > > > @@ -241,6 +239,10 @@ static int mei_hbm_prop_req(struct mei_device *dev) > > return 0; > > } > > > > + client_num = dev->me_client_presentation_num; > > + if (WARN_ON(dev->me_clients_num <= client_num)) > > + return -EIO; > > How can this happen? Why is spitting out a huge warning in the syslog > going to help anything? If a user can do this, then great, now you can > DoS your syslog :( > > If a user can't do this, then why tell them, it's your driver's bug that > you should just fix. This somehow should guard buffer overflow allocated of size dev->me_clients_num In theory this can happen only if something go wrong in hardware initialization or there is some other security hole that can change client_num. After this happen you probably won't be able to use the driver anyhow so I do not expect DoS on the syslog, but we can drop the WARN_ON but I would stick with the check Thanks Tomas