Subject: Re: [PATCH] wireless extensions: fix kernel heap content leak
From: Johannes Berg <johannes@sipsolutions.net>
To: Kees Cook <kees.cook@canonical.com>
Cc: "John W. Linville" <linville@tuxdriver.com>,
	linux-kernel@vger.kernel.org,
	"David S. Miller" <davem@davemloft.net>,
	Eric Dumazet <eric.dumazet@gmail.com>,
	Joe Perches <joe@perches.com>, Tejun Heo <tj@kernel.org>,
	linux-wireless@vger.kernel.org, netdev@vger.kernel.org,
	Jean Tourrilhes <jt@hpl.hp.com>
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	 <1283158704.3691.11.camel@jlt3.sipsolutions.net>
	 <1283162341.3691.45.camel@jlt3.sipsolutions.net>
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Date: Mon, 30 Aug 2010 20:06:30 +0200
Message-ID: <1283191590.3694.7.camel@jlt3.sipsolutions.net>
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Sender: linux-wireless-owner@vger.kernel.org

On Mon, 2010-08-30 at 11:03 -0700, Kees Cook wrote:
> Hi Johannes,
> 
> On Mon, Aug 30, 2010 at 12:24:54PM +0200, Johannes Berg wrote:
> > --- wireless-testing.orig/net/wireless/wext-compat.c	2010-08-30 12:04:57.000000000 +0200
> > +++ wireless-testing/net/wireless/wext-compat.c	2010-08-30 12:11:32.000000000 +0200
> > @@ -1420,6 +1420,9 @@ int cfg80211_wext_giwessid(struct net_de
> >  {
> >  	struct wireless_dev *wdev = dev->ieee80211_ptr;
> >  
> > +	data->flags = 0;
> > +	data->length = 0;
> > +
> >  	switch (wdev->iftype) {
> >  	case NL80211_IFTYPE_ADHOC:
> >  		return cfg80211_ibss_wext_giwessid(dev, info, data, ssid);
> 
> Thanks for all your work on this! Were you able to trigger the leak
> through cfg80211? If so, then this will need a CVE assigned and sent to
> stable too, I think.

Yes, I was, very easily, by doing an SIOCGIWESSID while unassociated,
with a large iwq->length set by userspace. I did CC stable on my patch,
but we can amend the commit by a CVE if so desired.

johannes