Return-path: Received: from 74-93-104-97-Washington.hfc.comcastbusiness.net ([74.93.104.97]:50255 "EHLO sunset.davemloft.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752270AbZLOJnK (ORCPT ); Tue, 15 Dec 2009 04:43:10 -0500 Date: Tue, 15 Dec 2009 01:43:08 -0800 (PST) Message-Id: <20091215.014308.77044043.davem@davemloft.net> To: daniel@caiaq.de Cc: linux-kernel@vger.kernel.org, dcbw@redhat.com, m.hirsch@raumfeld.com, netdev@vger.kernel.org, libertas-dev@lists.infradead.org, stable@kernel.org, linux-wireless@vger.kernel.org Subject: Re: [PATCH] wireless: wext: allocate space for NULL-termination for 32byte SSIDs From: David Miller In-Reply-To: <1260650850-16163-1-git-send-email-daniel@caiaq.de> References: <1260650850-16163-1-git-send-email-daniel@caiaq.de> Mime-Version: 1.0 Content-Type: Text/Plain; charset=us-ascii Sender: linux-wireless-owner@vger.kernel.org List-ID: From: Daniel Mack Date: Sun, 13 Dec 2009 04:47:30 +0800 > We've experienced a long standing bug when quickly switching from > ad-hoc to managed mode on a hardware using a Libertas chipset. Can you please CC: linux-wireless for wireless patches? Thanks. > The effect is that after a number of mode transistions (sometimes as few > as two sufficed), the kernel will oops at very strange locations, mostly > in something like __kmem_alloc(). > > While the root cause turned out to be an issue with the wpa-supplicant > which feeds the kernel driver with garbage, this occasion pointed out a > bug in the wireless wext core when SSIDs with 32 byte lengths are passed > from userspace. In this case, the string is not properly NULL-terminated > which causes some other part to corrupt memory. > > (In the particular case I observed, an SIOCSIWESSID was issued with > bogus data in iwp->pointer but iwp->length=32). > > I admitedly couldn't find where the actual corruption itself happens, > but with this trivial fix, I can't reproduce the bug anymore. > > Signed-off-by: Daniel Mack > Cc: Dan Williams > Cc: Michael Hirsch > Cc: netdev@vger.kernel.org > Cc: libertas-dev@lists.infradead.org > Cc: stable@kernel.org > --- > net/wireless/wext.c | 4 ++-- > 1 files changed, 2 insertions(+), 2 deletions(-) > --- > net/wireless/wext-core.c | 4 ++-- > 1 files changed, 2 insertions(+), 2 deletions(-) > > diff --git a/net/wireless/wext-core.c b/net/wireless/wext-core.c > index 5e1656b..3d8f4b0 100644 > --- a/net/wireless/wext-core.c > +++ b/net/wireless/wext-core.c > @@ -759,8 +759,8 @@ static int ioctl_standard_iw_point(struct iw_point *iwp, unsigned int cmd, > } > } > > - /* kzalloc() ensures NULL-termination for essid_compat. */ > - extra = kzalloc(extra_size, GFP_KERNEL); > + /* kzalloc() +1 ensures NULL-termination for essid_compat. */ > + extra = kzalloc(extra_size + 1, GFP_KERNEL); > if (!extra) > return -ENOMEM; > > -- > 1.6.3.3 > > -- > To unsubscribe from this list: send the line "unsubscribe linux-kernel" in > the body of a message to majordomo@vger.kernel.org > More majordomo info at http://vger.kernel.org/majordomo-info.html > Please read the FAQ at http://www.tux.org/lkml/