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=-19.0 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=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 3A1B9C433F7 for ; Mon, 29 Mar 2021 08:24:50 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 00E6D619D9 for ; Mon, 29 Mar 2021 08:24:49 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S233045AbhC2IYX (ORCPT ); Mon, 29 Mar 2021 04:24:23 -0400 Received: from mail.kernel.org ([198.145.29.99]:57848 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S233046AbhC2IPt (ORCPT ); Mon, 29 Mar 2021 04:15:49 -0400 Received: by mail.kernel.org (Postfix) with ESMTPSA id D59546196D; Mon, 29 Mar 2021 08:15:26 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1617005727; bh=43SFuyqFDg25OjiCtBvWthzGUpSNIkUtCbK5kUNqPKU=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=0AxwziBZNUNTd8RDABUV3XIGFKno5el/5F+HRbPrcpROmKC/kaI8Gc8s4u0V6Dkis i6PF7BuRNOGhY741AhJ5xXN8JSNdr1FZ5fLKBMkiP9pqhIwMPA7Vgw8v0VO5o1zYMz FHLcNKgXqVhNjOozYMv3muDFEKnGiJUIoHGZRTsk= 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 5.4 095/111] netfilter: x_tables: Use correct memory barriers. Date: Mon, 29 Mar 2021 09:58:43 +0200 Message-Id: <20210329075618.372991371@linuxfoundation.org> X-Mailer: git-send-email 2.31.1 In-Reply-To: <20210329075615.186199980@linuxfoundation.org> References: <20210329075615.186199980@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 [ 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 1b261c51b3a3..04e7f5630509 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 ef6d51a3798b..5c35d64d1f34 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 -- 2.30.1