From patchwork Fri Oct 7 08:32:31 2016 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Paul Durrant X-Patchwork-Id: 679176 X-Patchwork-Delegate: davem@davemloft.net Return-Path: X-Original-To: patchwork-incoming@ozlabs.org Delivered-To: patchwork-incoming@ozlabs.org Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by ozlabs.org (Postfix) with ESMTP id 3sr3GM3wKNz9s2Q for ; Fri, 7 Oct 2016 19:53:47 +1100 (AEDT) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754208AbcJGIxn (ORCPT ); Fri, 7 Oct 2016 04:53:43 -0400 Received: from smtp02.citrix.com ([66.165.176.63]:54752 "EHLO SMTP02.CITRIX.COM" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1756231AbcJGIxk (ORCPT ); Fri, 7 Oct 2016 04:53:40 -0400 X-IronPort-AV: E=Sophos;i="5.31,308,1473120000"; d="scan'208";a="391244821" From: Paul Durrant To: , CC: Paul Durrant , Wei Liu Subject: [PATCH v2 net] xen-netback: make sure that hashes are not send to unaware frontends Date: Fri, 7 Oct 2016 09:32:31 +0100 Message-ID: <1475829151-3707-1-git-send-email-paul.durrant@citrix.com> X-Mailer: git-send-email 2.1.4 MIME-Version: 1.0 X-DLP: MIA1 Sender: netdev-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: netdev@vger.kernel.org In the case when a frontend only negotiates a single queue with xen- netback it is possible for a skbuff with a s/w hash to result in a hash extra_info segment being sent to the frontend even when no hash algorithm has been configured. (The ndo_select_queue() entry point makes sure the hash is not set if no algorithm is configured, but this entry point is not called when there is only a single queue). This can result in a frontend that is unable to handle extra_info segments being given such a segment, causing it to crash. This patch fixes the problem by clearing the hash in ndo_start_xmit() instead, which is clearly guaranteed to be called irrespective of the number of queues. Signed-off-by: Paul Durrant Cc: Wei Liu Acked-by: Wei Liu --- v2: - Simplified and re-based onto re-factored net branch --- drivers/net/xen-netback/interface.c | 20 +++++++++----------- 1 file changed, 9 insertions(+), 11 deletions(-) diff --git a/drivers/net/xen-netback/interface.c b/drivers/net/xen-netback/interface.c index 4af532a..74dc2bf 100644 --- a/drivers/net/xen-netback/interface.c +++ b/drivers/net/xen-netback/interface.c @@ -149,17 +149,8 @@ static u16 xenvif_select_queue(struct net_device *dev, struct sk_buff *skb, struct xenvif *vif = netdev_priv(dev); unsigned int size = vif->hash.size; - if (vif->hash.alg == XEN_NETIF_CTRL_HASH_ALGORITHM_NONE) { - u16 index = fallback(dev, skb) % dev->real_num_tx_queues; - - /* Make sure there is no hash information in the socket - * buffer otherwise it would be incorrectly forwarded - * to the frontend. - */ - skb_clear_hash(skb); - - return index; - } + if (vif->hash.alg == XEN_NETIF_CTRL_HASH_ALGORITHM_NONE) + return fallback(dev, skb) % dev->real_num_tx_queues; xenvif_set_skb_hash(vif, skb); @@ -208,6 +199,13 @@ static int xenvif_start_xmit(struct sk_buff *skb, struct net_device *dev) cb = XENVIF_RX_CB(skb); cb->expires = jiffies + vif->drain_timeout; + /* If there is no hash algorithm configured then make sure there + * is no hash information in the socket buffer otherwise it + * would be incorrectly forwarded to the frontend. + */ + if (vif->hash.alg == XEN_NETIF_CTRL_HASH_ALGORITHM_NONE) + skb_clear_hash(skb); + xenvif_rx_queue_tail(queue, skb); xenvif_kick_thread(queue);