Return-path: Received: from charlotte.tuxdriver.com ([70.61.120.58]:60831 "EHLO smtp.tuxdriver.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1756566Ab3FSOAL (ORCPT ); Wed, 19 Jun 2013 10:00:11 -0400 Date: Wed, 19 Jun 2013 09:51:35 -0400 From: "John W. Linville" To: David Miller Cc: johannes@sipsolutions.net, torvalds@linux-foundation.org, linux-wireless@vger.kernel.org, netdev@vger.kernel.org Subject: Re: [PATCH] nl80211: fix attrbuf access race by allocating a separate one Message-ID: <20130619135134.GA12079@tuxdriver.com> (sfid-20130619_160017_277953_C9E08A37) References: <1371628488.8349.3.camel@jlt4.sipsolutions.net> <1371630238.8349.6.camel@jlt4.sipsolutions.net> <20130619.013900.786603036908799505.davem@davemloft.net> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii In-Reply-To: <20130619.013900.786603036908799505.davem@davemloft.net> Sender: linux-wireless-owner@vger.kernel.org List-ID: On Wed, Jun 19, 2013 at 01:39:00AM -0700, David Miller wrote: > From: Johannes Berg > Date: Wed, 19 Jun 2013 10:23:58 +0200 > > > From: Johannes Berg > > > > Since my commit 3713b4e364, nl80211_dump_wiphy() uses the global > > nl80211_fam.attrbuf for parsing the incoming data. This wouldn't > > be a problem if it only did so on the first dump iteration which > > is locked against other commands in generic netlink, but due to > > space constraints in cb->args (the needed state doesn't fit) I > > decided to always parse the original message. That's racy though > > since nl80211_fam.attrbuf could be used by some other parsing in > > generic netlink concurrently. > > > > For now, fix this by allocating a separate parse buffer (it's a > > bit too big for the stack, currently 1448 bytes on 64-bit). For > > -next, I'll change the code to parse into the global buffer in > > the first round only and then allocate a smaller buffer to keep > > the state in cb->args. > > > > Reported-by: Linus Torvalds > > Signed-off-by: Johannes Berg > > Acked-by: David S. Miller Acked-by: John W. Linville -- John W. Linville Someday the world will need a hero, and you linville@tuxdriver.com might be all we have. Be ready.