From mboxrd@z Thu Jan 1 00:00:00 1970 From: Ben Hutchings Subject: Re: [PATCH] net: clear heap allocations for privileged ethtool actions Date: Thu, 07 Oct 2010 22:34:44 +0100 Message-ID: <1286487284.2271.37.camel@achroite.uk.solarflarecom.com> References: <20101007211004.GA20267@outflux.net> Mime-Version: 1.0 Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: 7bit Cc: linux-kernel@vger.kernel.org, "David S. Miller" , Jeff Garzik , Jeff Kirsher , Peter P Waskiewicz Jr , netdev@vger.kernel.org To: Kees Cook Return-path: Received: from mail.solarflare.com ([216.237.3.220]:53116 "EHLO exchange.solarflare.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1750826Ab0JGVet (ORCPT ); Thu, 7 Oct 2010 17:34:49 -0400 In-Reply-To: <20101007211004.GA20267@outflux.net> Sender: netdev-owner@vger.kernel.org List-ID: On Thu, 2010-10-07 at 14:10 -0700, Kees Cook wrote: > Several other ethtool functions leave heap uncleared (potentially) by > drivers. Some interfaces appear safe (eeprom, etc), in that the sizes > are well controlled. In some situations (e.g. unchecked error conditions), > the heap will remain unchanged in areas before copying back to userspace. > Note that these are less of an issue since these all require CAP_NET_ADMIN. > > Cc: stable@kernel.org > Signed-off-by: Kees Cook > --- > net/core/ethtool.c | 6 +++--- > 1 files changed, 3 insertions(+), 3 deletions(-) > > diff --git a/net/core/ethtool.c b/net/core/ethtool.c > index 7a85367..fb9cf30 100644 > --- a/net/core/ethtool.c > +++ b/net/core/ethtool.c > @@ -397,7 +397,7 @@ static noinline_for_stack int ethtool_get_rxfh_indir(struct net_device *dev, > (KMALLOC_MAX_SIZE - sizeof(*indir)) / sizeof(*indir->ring_index)) > return -ENOMEM; > full_size = sizeof(*indir) + sizeof(*indir->ring_index) * table_size; > - indir = kmalloc(full_size, GFP_USER); > + indir = kzalloc(full_size, GFP_USER); > if (!indir) > return -ENOMEM; > [...] Acked-by: Ben Hutchings You could alternately recalculate full_size before copying back to the user buffer: full_size = sizeof(*indir) + sizeof(*indir->ring_index) * indir->size; but kzalloc() is more obviously safe. Ben. -- Ben Hutchings, Senior Software Engineer, Solarflare Communications Not speaking for my employer; that's the marketing department's job. They asked us to note that Solarflare product names are trademarked.