From patchwork Mon Mar 29 07:58:57 2021 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Greg Kroah-Hartman X-Patchwork-Id: 411280 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=-19.0 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, USER_AGENT_GIT autolearn=ham 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 ABCE8C433E1 for ; Mon, 29 Mar 2021 08:40:14 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 887FA619B9 for ; Mon, 29 Mar 2021 08:40:14 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S234871AbhC2Ijs (ORCPT ); Mon, 29 Mar 2021 04:39:48 -0400 Received: from mail.kernel.org ([198.145.29.99]:60728 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S235199AbhC2IiV (ORCPT ); Mon, 29 Mar 2021 04:38:21 -0400 Received: by mail.kernel.org (Postfix) with ESMTPSA id CBF7161582; Mon, 29 Mar 2021 08:38:20 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1617007101; bh=sDBqcHPhIHDIZShWpfUiPbvZed99NKuOLc6eLpnFItw=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=O2u0FujA85wfhAkJQvFZu+s19BJ+RLaHg/D1DZ69KCpg8Hak+lYwbj2wD+fRSobXA AhAeYqJtN1J5eoB8zkM/yxEbqJBTyEafstsBOIzQTKEUlfsSqZciZDrO2L1pXTxZz+ Zpun9SKR31ovw5YW50NhZ71WvmUF0NzFtO6LGqFg= From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, Mark Tomlinson , Pablo Neira Ayuso , Sasha Levin Subject: [PATCH 5.11 221/254] netfilter: x_tables: Use correct memory barriers. Date: Mon, 29 Mar 2021 09:58:57 +0200 Message-Id: <20210329075640.359001827@linuxfoundation.org> X-Mailer: git-send-email 2.31.1 In-Reply-To: <20210329075633.135869143@linuxfoundation.org> References: <20210329075633.135869143@linuxfoundation.org> User-Agent: quilt/0.66 MIME-Version: 1.0 Precedence: bulk List-ID: X-Mailing-List: stable@vger.kernel.org From: Mark Tomlinson [ Upstream commit 175e476b8cdf2a4de7432583b49c871345e4f8a1 ] 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 Signed-off-by: Sasha Levin --- include/linux/netfilter/x_tables.h | 2 +- net/netfilter/x_tables.c | 2 +- 2 files changed, 2 insertions(+), 2 deletions(-) diff --git a/include/linux/netfilter/x_tables.h b/include/linux/netfilter/x_tables.h index 5deb099d156d..8ec48466410a 100644 --- a/include/linux/netfilter/x_tables.h +++ b/include/linux/netfilter/x_tables.h @@ -376,7 +376,7 @@ static inline unsigned int xt_write_recseq_begin(void) * since addend is most likely 1 */ __this_cpu_add(xt_recseq.sequence, addend); - smp_wmb(); + smp_mb(); return addend; } diff --git a/net/netfilter/x_tables.c b/net/netfilter/x_tables.c index 7df3aef39c5c..6bd31a7a27fc 100644 --- a/net/netfilter/x_tables.c +++ b/net/netfilter/x_tables.c @@ -1389,7 +1389,7 @@ xt_replace_table(struct xt_table *table, table->private = newinfo; /* make sure all cpus see new ->private value */ - smp_wmb(); + smp_mb(); /* * Even though table entries have now been swapped, other CPU's