From mboxrd@z Thu Jan 1 00:00:00 1970 From: David Miller Subject: [PATCH 4/15] l2tp: Fix locking in l2tp_core.c Date: Sun, 08 May 2011 15:37:27 -0700 (PDT) Message-ID: <20110508.153727.112619158.davem@davemloft.net> Mime-Version: 1.0 Content-Type: Text/Plain; charset=us-ascii Content-Transfer-Encoding: 7bit To: netdev@vger.kernel.org Return-path: Received: from 74-93-104-97-Washington.hfc.comcastbusiness.net ([74.93.104.97]:42638 "EHLO sunset.davemloft.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1755698Ab1EHWh7 (ORCPT ); Sun, 8 May 2011 18:37:59 -0400 Received: from localhost (localhost [127.0.0.1]) by sunset.davemloft.net (Postfix) with ESMTP id 5977624C087 for ; Sun, 8 May 2011 15:37:27 -0700 (PDT) Sender: netdev-owner@vger.kernel.org List-ID: l2tp_xmit_skb() must take the socket lock. It makes use of ip_queue_xmit() which expects to execute in a socket atomic context. Since we execute this function in software interrupts, we cannot use the usual lock_sock()/release_sock() sequence, instead we have to use bh_lock_sock() and see if a user has the socket locked, and if so drop the packet. Signed-off-by: David S. Miller --- net/l2tp/l2tp_core.c | 8 ++++++++ 1 files changed, 8 insertions(+), 0 deletions(-) diff --git a/net/l2tp/l2tp_core.c b/net/l2tp/l2tp_core.c index c64ce0a..7853029 100644 --- a/net/l2tp/l2tp_core.c +++ b/net/l2tp/l2tp_core.c @@ -1060,6 +1060,12 @@ int l2tp_xmit_skb(struct l2tp_session *session, struct sk_buff *skb, int hdr_len IPSKB_REROUTED); nf_reset(skb); + bh_lock_sock(sk); + if (sock_owned_by_user(sk)) { + dev_kfree_skb(skb); + goto out_unlock; + } + /* Get routing info from the tunnel socket */ skb_dst_drop(skb); skb_dst_set(skb, dst_clone(__sk_dst_get(sk))); @@ -1106,6 +1112,8 @@ int l2tp_xmit_skb(struct l2tp_session *session, struct sk_buff *skb, int hdr_len l2tp_skb_set_owner_w(skb, sk); l2tp_xmit_core(session, skb, data_len); +out_unlock: + bh_unlock_sock(sk); abort: return 0; -- 1.7.5.1