From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-3.8 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED autolearn=no autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 30780C32751 for ; Sat, 10 Aug 2019 20:51:09 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 110AE208C4 for ; Sat, 10 Aug 2019 20:51:09 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727621AbfHJUuq (ORCPT ); Sat, 10 Aug 2019 16:50:46 -0400 Received: from shadbolt.e.decadent.org.uk ([88.96.1.126]:54372 "EHLO shadbolt.e.decadent.org.uk" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726693AbfHJUnz (ORCPT ); Sat, 10 Aug 2019 16:43:55 -0400 Received: from [192.168.4.242] (helo=deadeye) by shadbolt.decadent.org.uk with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.89) (envelope-from ) id 1hwYDQ-00053q-5v; Sat, 10 Aug 2019 21:43:52 +0100 Received: from ben by deadeye with local (Exim 4.92) (envelope-from ) id 1hwYDN-0003hZ-89; Sat, 10 Aug 2019 21:43:49 +0100 Content-Type: text/plain; charset="UTF-8" Content-Disposition: inline Content-Transfer-Encoding: 8bit MIME-Version: 1.0 From: Ben Hutchings To: linux-kernel@vger.kernel.org, stable@vger.kernel.org CC: akpm@linux-foundation.org, Denis Kirjanov , "David S. Miller" , "Eric Dumazet" , "James Chapman" Date: Sat, 10 Aug 2019 21:40:07 +0100 Message-ID: X-Mailer: LinuxStableQueue (scripts by bwh) X-Patchwork-Hint: ignore Subject: [PATCH 3.16 111/157] l2tp: use rcu_dereference_sk_user_data() in l2tp_udp_encap_recv() In-Reply-To: X-SA-Exim-Connect-IP: 192.168.4.242 X-SA-Exim-Mail-From: ben@decadent.org.uk X-SA-Exim-Scanned: No (on shadbolt.decadent.org.uk); SAEximRunCond expanded to false Sender: stable-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: stable@vger.kernel.org 3.16.72-rc1 review patch. If anyone has any objections, please let me know. ------------------ From: Eric Dumazet commit c1c477217882c610a2ba0268f5faf36c9c092528 upstream. Canonical way to fetch sk_user_data from an encap_rcv() handler called from UDP stack in rcu protected section is to use rcu_dereference_sk_user_data(), otherwise compiler might read it multiple times. Fixes: d00fa9adc528 ("il2tp: fix races with tunnel socket close") Signed-off-by: Eric Dumazet Cc: James Chapman Signed-off-by: David S. Miller Signed-off-by: Ben Hutchings --- net/l2tp/l2tp_core.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) --- a/net/l2tp/l2tp_core.c +++ b/net/l2tp/l2tp_core.c @@ -997,7 +997,7 @@ int l2tp_udp_encap_recv(struct sock *sk, { struct l2tp_tunnel *tunnel; - tunnel = l2tp_tunnel(sk); + tunnel = rcu_dereference_sk_user_data(sk); if (tunnel == NULL) goto pass_up;