From mboxrd@z Thu Jan 1 00:00:00 1970 From: David Miller Subject: Re: [PATCH net] l2tp: fix use-after-free during module unload Date: Thu, 01 Sep 2016 16:34:16 -0700 (PDT) Message-ID: <20160901.163416.76744449780953103.davem@davemloft.net> References: Mime-Version: 1.0 Content-Type: Text/Plain; charset=us-ascii Content-Transfer-Encoding: 7bit Cc: netdev@vger.kernel.org To: sd@queasysnail.net Return-path: Received: from shards.monkeyblade.net ([184.105.139.130]:40660 "EHLO shards.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752151AbcIAXeR (ORCPT ); Thu, 1 Sep 2016 19:34:17 -0400 In-Reply-To: Sender: netdev-owner@vger.kernel.org List-ID: From: Sabrina Dubroca Date: Tue, 30 Aug 2016 16:05:16 +0200 > Tunnel deletion is delayed by both a workqueue (l2tp_tunnel_delete -> wq > -> l2tp_tunnel_del_work) and RCU (sk_destruct -> RCU -> > l2tp_tunnel_destruct). > > By the time l2tp_tunnel_destruct() runs to destroy the tunnel and finish > destroying the socket, the private data reserved via the net_generic > mechanism has already been freed, but l2tp_tunnel_destruct() actually > uses this data. > > Make sure tunnel deletion for the netns has completed before returning > from l2tp_net_exit() by first flushing the tunnel removal workqueue, and > then waiting for RCU callbacks to complete. > > Fixes: 167eb17e0b17 ("l2tp: create tunnel sockets in the right namespace") > Signed-off-by: Sabrina Dubroca Please resubmit this with Sergei's feedback addressed. Thanks.