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=-19.1 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_CR_TRAILER,INCLUDES_PATCH,MAILING_LIST_MULTI,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 5D651C47080 for ; Mon, 31 May 2021 13:16:35 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 405D66108D for ; Mon, 31 May 2021 13:16:35 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S231601AbhEaNSM (ORCPT ); Mon, 31 May 2021 09:18:12 -0400 Received: from mail.kernel.org ([198.145.29.99]:53022 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S231330AbhEaNSA (ORCPT ); Mon, 31 May 2021 09:18:00 -0400 Received: by mail.kernel.org (Postfix) with ESMTPSA id AC37A6135D; Mon, 31 May 2021 13:16:19 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1622466980; bh=aEOG8s1btNRx6uC+MOC4W0QMUsNhnm6l0q2TlVN8zII=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=yuhzq2/EpGBpos75nlUcqc/lEIXlopOwG+d0vrUjQEkRDukD9JwFuw+bvEQVVa4my Ja0VLHrHcsT6vSjY/qC7HtdJHpP1LzYHTO9Xwck7um9QaHKEzs4V4T7e/qT71m4FAo Ox5kpBw63wRGfU4smMNtioZxATIL8j9W5bp1178I= From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, Mark Tomlinson , Pablo Neira Ayuso , "Pavel Machek (CIP)" , "Nobuhiro Iwamatsu (CIP)" Subject: [PATCH 4.4 02/54] netfilter: x_tables: Use correct memory barriers. Date: Mon, 31 May 2021 15:13:28 +0200 Message-Id: <20210531130635.154707451@linuxfoundation.org> X-Mailer: git-send-email 2.31.1 In-Reply-To: <20210531130635.070310929@linuxfoundation.org> References: <20210531130635.070310929@linuxfoundation.org> User-Agent: quilt/0.66 MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org From: Mark Tomlinson commit 175e476b8cdf2a4de7432583b49c871345e4f8a1 upstream. When a new table value was assigned, it was followed by a write memory barrier. This ensured that all writes before this point would complete before any writes after this point. However, to determine whether the rules are unused, the sequence counter is read. To ensure that all writes have been done before these reads, a full memory barrier is needed, not just a write memory barrier. The same argument applies when incrementing the counter, before the rules are read. Changing to using smp_mb() instead of smp_wmb() fixes the kernel panic reported in cc00bcaa5899 (which is still present), while still maintaining the same speed of replacing tables. The smb_mb() barriers potentially slow the packet path, however testing has shown no measurable change in performance on a 4-core MIPS64 platform. Fixes: 7f5c6d4f665b ("netfilter: get rid of atomic ops in fast path") Signed-off-by: Mark Tomlinson Signed-off-by: Pablo Neira Ayuso [Ported to stable, affected barrier is added by d3d40f237480abf3268956daf18cdc56edd32834 in mainline] Signed-off-by: Pavel Machek (CIP) Signed-off-by: Nobuhiro Iwamatsu (CIP) Signed-off-by: Greg Kroah-Hartman --- include/linux/netfilter/x_tables.h | 2 +- net/netfilter/x_tables.c | 3 +++ 2 files changed, 4 insertions(+), 1 deletion(-) --- a/include/linux/netfilter/x_tables.h +++ b/include/linux/netfilter/x_tables.h @@ -327,7 +327,7 @@ static inline unsigned int xt_write_recs * since addend is most likely 1 */ __this_cpu_add(xt_recseq.sequence, addend); - smp_wmb(); + smp_mb(); return addend; } --- a/net/netfilter/x_tables.c +++ b/net/netfilter/x_tables.c @@ -1140,6 +1140,9 @@ xt_replace_table(struct xt_table *table, smp_wmb(); table->private = newinfo; + /* make sure all cpus see new ->private value */ + smp_mb(); + /* * Even though table entries have now been swapped, other CPU's * may still be using the old entries. This is okay, because