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=-4.0 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_PASS 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 A9A53C43387 for ; Mon, 7 Jan 2019 17:10:34 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 71BAF2147C for ; Mon, 7 Jan 2019 17:10:34 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727139AbfAGRKd (ORCPT ); Mon, 7 Jan 2019 12:10:33 -0500 Received: from shards.monkeyblade.net ([23.128.96.9]:58676 "EHLO shards.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726893AbfAGRKd (ORCPT ); Mon, 7 Jan 2019 12:10:33 -0500 Received: from localhost (unknown [144.121.20.163]) (using TLSv1 with cipher AES256-SHA (256/256 bits)) (Client did not present a certificate) (Authenticated sender: davem-davemloft) by shards.monkeyblade.net (Postfix) with ESMTPSA id 5E99C1015DD06; Mon, 7 Jan 2019 09:10:32 -0800 (PST) Date: Mon, 07 Jan 2019 09:10:31 -0800 (PST) Message-Id: <20190107.091031.100384065611982323.davem@davemloft.net> To: kchen@synology.com Cc: nikolay@cumulusnetworks.com, netdev@vger.kernel.org, linux-kernel@vger.kernel.org Subject: Re: [PATCH 1/1] net: bridge: fix a bug on using a neighbour cache entry without checking its state From: David Miller In-Reply-To: <1546745293-5678-1-git-send-email-kchen@synology.com> References: <1546745293-5678-1-git-send-email-kchen@synology.com> X-Mailer: Mew version 6.8 on Emacs 26.1 Mime-Version: 1.0 Content-Type: Text/Plain; charset=us-ascii Content-Transfer-Encoding: 7bit X-Greylist: Sender succeeded SMTP AUTH, not delayed by milter-greylist-4.5.12 (shards.monkeyblade.net [149.20.54.216]); Mon, 07 Jan 2019 09:10:32 -0800 (PST) Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org From: kchen Date: Sun, 6 Jan 2019 11:28:13 +0800 > From: JianJhen Chen > > When handling DNAT'ed packets on a bridge device, the neighbour cache entry > from lookup was used without checking its state. It means that a cache entry > in the NUD_STALE state will be used directly instead of entering the NUD_DELAY > state to confirm the reachability of the neighbor. > > This problem becomes worse after commit 2724680bceee ("neigh: Keep neighbour > cache entries if number of them is small enough."), since all neighbour cache > entries in the NUD_STALE state will be kept in the neighbour table as long as > the number of cache entries does not exceed the value specified in gc_thresh1. > > This commit validates the state of a neighbour cache entry before using > the entry. > > Signed-off-by: JianJhen Chen > Reviewed-by: JinLin Chen Indeed, this looks correct. Applied and queued up for -stable, thanks.