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=-10.0 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI, SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED,USER_AGENT_GIT autolearn=unavailable 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 1E279C433E7 for ; Mon, 20 Jul 2020 15:49:52 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id DE44B2065E for ; Mon, 20 Jul 2020 15:49:51 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1595260192; bh=uORrc+8HBjJ7VP7+P3vFQQKH9HLm2dnB8CiN/Kk4KhI=; h=From:To:Cc:Subject:Date:In-Reply-To:References:List-ID:From; b=j2nWnhwiLtDAJVzv6lEW7vRScU/diheSCHY7PYOtAfNRFMPQOUIjvVIh40Q7npx19 uPo0lw0nAXQjxkB4TPXgrBw8H8ZWlzJ/OzfrNnLqH6spPS10apqYCzoDvsAvd7Zb1a yE5bH6xDyk7LAPK0siDW67HefDKmu9nCdNPRWmyo= Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1731045AbgGTPtu (ORCPT ); Mon, 20 Jul 2020 11:49:50 -0400 Received: from mail.kernel.org ([198.145.29.99]:45962 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1731036AbgGTPtq (ORCPT ); Mon, 20 Jul 2020 11:49:46 -0400 Received: from localhost (83-86-89-107.cable.dynamic.v4.ziggo.nl [83.86.89.107]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPSA id 6A07822482; Mon, 20 Jul 2020 15:49:45 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1595260185; bh=uORrc+8HBjJ7VP7+P3vFQQKH9HLm2dnB8CiN/Kk4KhI=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=qRpDf0WyL30YjGY6vxxljbOZoaJxzDATbAtOXlznVT6Wd7N362rD612BAXHzWhy2i MeLIDTSjtAmHcQBv69iJdmnpkJwA2H56wlZ1IaJ2gR95tV2UKVoYv1SNAIM8UjlcQ8 JBAqJDJgXgZRBUM7T0SJC4YfDd6JiLEdezOQfqjE= From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, Eric Dumazet , Mathieu Desnoyers , "David S. Miller" Subject: [PATCH 4.19 012/133] tcp: md5: add missing memory barriers in tcp_md5_do_add()/tcp_md5_hash_key() Date: Mon, 20 Jul 2020 17:35:59 +0200 Message-Id: <20200720152804.324509468@linuxfoundation.org> X-Mailer: git-send-email 2.27.0 In-Reply-To: <20200720152803.732195882@linuxfoundation.org> References: <20200720152803.732195882@linuxfoundation.org> User-Agent: quilt/0.66 MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org From: Eric Dumazet [ Upstream commit 6a2febec338df7e7699a52d00b2e1207dcf65b28 ] MD5 keys are read with RCU protection, and tcp_md5_do_add() might update in-place a prior key. Normally, typical RCU updates would allocate a new piece of memory. In this case only key->key and key->keylen might be updated, and we do not care if an incoming packet could see the old key, the new one, or some intermediate value, since changing the key on a live flow is known to be problematic anyway. We only want to make sure that in the case key->keylen is changed, cpus in tcp_md5_hash_key() wont try to use uninitialized data, or crash because key->keylen was read twice to feed sg_init_one() and ahash_request_set_crypt() Fixes: 9ea88a153001 ("tcp: md5: check md5 signature without socket lock") Signed-off-by: Eric Dumazet Cc: Mathieu Desnoyers Signed-off-by: David S. Miller Signed-off-by: Greg Kroah-Hartman --- net/ipv4/tcp.c | 7 +++++-- net/ipv4/tcp_ipv4.c | 3 +++ 2 files changed, 8 insertions(+), 2 deletions(-) --- a/net/ipv4/tcp.c +++ b/net/ipv4/tcp.c @@ -3756,10 +3756,13 @@ EXPORT_SYMBOL(tcp_md5_hash_skb_data); int tcp_md5_hash_key(struct tcp_md5sig_pool *hp, const struct tcp_md5sig_key *key) { + u8 keylen = key->keylen; struct scatterlist sg; - sg_init_one(&sg, key->key, key->keylen); - ahash_request_set_crypt(hp->md5_req, &sg, NULL, key->keylen); + smp_rmb(); /* paired with smp_wmb() in tcp_md5_do_add() */ + + sg_init_one(&sg, key->key, keylen); + ahash_request_set_crypt(hp->md5_req, &sg, NULL, keylen); return crypto_ahash_update(hp->md5_req); } EXPORT_SYMBOL(tcp_md5_hash_key); --- a/net/ipv4/tcp_ipv4.c +++ b/net/ipv4/tcp_ipv4.c @@ -1065,6 +1065,9 @@ int tcp_md5_do_add(struct sock *sk, cons if (key) { /* Pre-existing entry - just update that one. */ memcpy(key->key, newkey, newkeylen); + + smp_wmb(); /* pairs with smp_rmb() in tcp_md5_hash_key() */ + key->keylen = newkeylen; return 0; }