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=-3.7 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 A6125C35242 for ; Sat, 8 Feb 2020 18:32:09 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 2F061217BA for ; Sat, 8 Feb 2020 18:32:09 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1728420AbgBHScI (ORCPT ); Sat, 8 Feb 2020 13:32:08 -0500 Received: from shadbolt.e.decadent.org.uk ([88.96.1.126]:34694 "EHLO shadbolt.e.decadent.org.uk" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1727961AbgBHS3t (ORCPT ); Sat, 8 Feb 2020 13:29:49 -0500 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 1j0UrO-0003ir-4k; Sat, 08 Feb 2020 18:29:42 +0000 Received: from ben by deadeye with local (Exim 4.93) (envelope-from ) id 1j0UrN-000CXG-59; Sat, 08 Feb 2020 18:29:41 +0000 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 , "Greg Kroah-Hartman" , "Eric Dumazet" , "David S. Miller" , "Guillaume Nault" Date: Sat, 08 Feb 2020 18:21:22 +0000 Message-ID: X-Mailer: LinuxStableQueue (scripts by bwh) X-Patchwork-Hint: ignore Subject: [PATCH 3.16 143/148] tcp: Protect accesses to .ts_recent_stamp with {READ,WRITE}_ONCE() 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: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org 3.16.82-rc1 review patch. If anyone has any objections, please let me know. ------------------ From: Guillaume Nault commit 721c8dafad26ccfa90ff659ee19755e3377b829d upstream. Syncookies borrow the ->rx_opt.ts_recent_stamp field to store the timestamp of the last synflood. Protect them with READ_ONCE() and WRITE_ONCE() since reads and writes aren't serialised. Use of .rx_opt.ts_recent_stamp for storing the synflood timestamp was introduced by a0f82f64e269 ("syncookies: remove last_synq_overflow from struct tcp_sock"). But unprotected accesses were already there when timestamp was stored in .last_synq_overflow. Fixes: 1da177e4c3f4 ("Linux-2.6.12-rc2") Signed-off-by: Guillaume Nault Signed-off-by: Eric Dumazet Signed-off-by: David S. Miller Signed-off-by: Greg Kroah-Hartman [bwh: Backported to 3.16: Use ACCESS_ONCE() instead of {READ,WRITE}_ONCE()] Signed-off-by: Ben Hutchings --- include/net/tcp.h | 6 +++--- 1 file changed, 3 insertions(+), 3 deletions(-) --- a/include/net/tcp.h +++ b/include/net/tcp.h @@ -482,17 +482,17 @@ struct sock *cookie_v4_check(struct sock */ static inline void tcp_synq_overflow(struct sock *sk) { - unsigned long last_overflow = tcp_sk(sk)->rx_opt.ts_recent_stamp; + unsigned long last_overflow = ACCESS_ONCE(tcp_sk(sk)->rx_opt.ts_recent_stamp); unsigned long now = jiffies; if (!time_between32(now, last_overflow, last_overflow + HZ)) - tcp_sk(sk)->rx_opt.ts_recent_stamp = now; + ACCESS_ONCE(tcp_sk(sk)->rx_opt.ts_recent_stamp) = now; } /* syncookies: no recent synqueue overflow on this listening socket? */ static inline bool tcp_synq_no_recent_overflow(const struct sock *sk) { - unsigned long last_overflow = tcp_sk(sk)->rx_opt.ts_recent_stamp; + unsigned long last_overflow = ACCESS_ONCE(tcp_sk(sk)->rx_opt.ts_recent_stamp); return time_after(jiffies, last_overflow + TCP_SYNCOOKIE_VALID); }