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=-10.8 required=3.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_CR_TRAILER, MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS 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 C3C63C433E9 for ; Fri, 8 Jan 2021 07:35:17 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 7BE0523435 for ; Fri, 8 Jan 2021 07:35:17 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1725793AbhAHHfB (ORCPT ); Fri, 8 Jan 2021 02:35:01 -0500 Received: from mail.kernel.org ([198.145.29.99]:49080 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1725791AbhAHHfA (ORCPT ); Fri, 8 Jan 2021 02:35:00 -0500 Received: by mail.kernel.org (Postfix) with ESMTPSA id 4562523403; Fri, 8 Jan 2021 07:34:19 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1610091260; bh=ET7EZ4mvypeXbGjc6I95Szrku1HDtcYcljZd497LRCk=; h=Date:From:To:Cc:Subject:References:In-Reply-To:From; b=1AKdmLGWNoFs4I4RUZUXI4nRu4Gvzplk5OuaUSq0tUYrXaWfobwlD+AfAQf1fWVy/ lA2NuiuqvqUnQQTSh9BEgb+St3vMr7BT/djoUSnbub56JhCkBkUBdt7Lw45zsrBRiy VqVTG7vGlC+79EUir++sxgYHPw9UhIacV/onh0vs= Date: Fri, 8 Jan 2021 08:34:16 +0100 From: Greg KH To: Your Real Name Cc: David Miller , sashal@kernel.org, edumazet@google.com, vvs@virtuozzo.com, netdev@vger.kernel.org, stable@vger.kernel.org, linux-kernel@vger.kernel.org Subject: Re: [PATCH] neighbour: Disregard DEAD dst in neigh_update Message-ID: References: <20201230225415.GA490@ucf43ac461c9a53.ant.amazon.com> <20210105.160521.1279064249478522010.davem@davemloft.net> <20210108023637.GA31904@ucf43ac461c9a53.ant.amazon.com> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline Content-Transfer-Encoding: 8bit In-Reply-To: <20210108023637.GA31904@ucf43ac461c9a53.ant.amazon.com> Precedence: bulk List-ID: X-Mailing-List: stable@vger.kernel.org On Thu, Jan 07, 2021 at 09:36:37PM -0500, Your Real Name wrote: > On Tue, Jan 05, 2021 at 04:05:21PM -0800, David Miller wrote: > > > > > > From: Tong Zhu > > Date: Wed, 30 Dec 2020 17:54:23 -0500 > > > > > In 4.x kernel a dst in DST_OBSOLETE_DEAD state is associated > > > with loopback net_device and leads to loopback neighbour. It > > > leads to an ethernet header with all zero addresses. > > > > > > A very troubling case is working with mac80211 and ath9k. > > > A packet with all zero source MAC address to mac80211 will > > > eventually fail ieee80211_find_sta_by_ifaddr in ath9k (xmit.c). > > > As result, ath9k flushes tx queue (ath_tx_complete_aggr) without > > > updating baw (block ack window), damages baw logic and disables > > > transmission. > > > > > > Signed-off-by: Tong Zhu > > > > Please repost with an appropriate Fixes: tag. > > > > Thanks. > > I had a second thought on this. This fix should go mainline too. This is a > case we are sending out queued packets when arp reply from the neighbour > comes in. With 5.x kernel, a dst in DST_OBSOLETE_DEAD state leads to dropping > of this packet. It is not as bad as with 4.x kernel that may end up with an > all-zero mac address packet out to ethernet or choking up ath9k when using > block ack. Dropping the packet is still wrong. I’ll repost as a fix to > mainline and target backport to 4.x LTS releases. That's how kernel development works, please read https://www.kernel.org/doc/html/latest/process/stable-kernel-rules.html for how stable kernels are allowed to accept patches. good luck! greg k-h