From mboxrd@z Thu Jan 1 00:00:00 1970 From: Wei Liu Subject: [PATCH 2/6] xen-netfront: reduce gso_max_size to account for ethernet header Date: Mon, 25 Mar 2013 11:08:18 +0000 Message-ID: <1364209702-12437-3-git-send-email-wei.liu2@citrix.com> References: <1364209702-12437-1-git-send-email-wei.liu2@citrix.com> Mime-Version: 1.0 Content-Type: text/plain Cc: , , , , Wei Liu To: , Return-path: Received: from smtp.citrix.com ([66.165.176.89]:64946 "EHLO SMTP.CITRIX.COM" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1756560Ab3CYLJE (ORCPT ); Mon, 25 Mar 2013 07:09:04 -0400 In-Reply-To: <1364209702-12437-1-git-send-email-wei.liu2@citrix.com> Sender: netdev-owner@vger.kernel.org List-ID: The maximum packet including ethernet header that can be handled by netfront / netback wire format is 65535. Reduce gso_max_size accordingly. Drop skb and print warning when skb->len > 65535. This can 1) save the effort to send malformed packet to netback, 2) help spotting misconfiguration of netfront in the future. Signed-off-by: Wei Liu --- drivers/net/xen-netfront.c | 14 ++++++++++++++ 1 file changed, 14 insertions(+) diff --git a/drivers/net/xen-netfront.c b/drivers/net/xen-netfront.c index 5527663..3ae9dc1 100644 --- a/drivers/net/xen-netfront.c +++ b/drivers/net/xen-netfront.c @@ -547,6 +547,18 @@ static int xennet_start_xmit(struct sk_buff *skb, struct net_device *dev) unsigned int len = skb_headlen(skb); unsigned long flags; + /* Wire format of xen_netif_tx_request only supports skb->len + * < 64K, because size field in xen_netif_tx_request is + * uint16_t. If skb->len is too big, drop it and alert user about + * misconfiguration. + */ + if (unlikely(skb->len >= (uint16_t)(~0))) { + net_alert_ratelimited( + "xennet: skb->len = %u, too big for wire format\n", + skb->len); + goto drop; + } + slots = DIV_ROUND_UP(offset + len, PAGE_SIZE) + xennet_count_skb_frag_slots(skb); if (unlikely(slots > MAX_SKB_FRAGS + 1)) { @@ -1362,6 +1374,8 @@ static struct net_device *xennet_create_dev(struct xenbus_device *dev) SET_ETHTOOL_OPS(netdev, &xennet_ethtool_ops); SET_NETDEV_DEV(netdev, &dev->dev); + netif_set_gso_max_size(netdev, 65535 - ETH_HLEN); + np->netdev = netdev; netif_carrier_off(netdev); -- 1.7.10.4