From mboxrd@z Thu Jan 1 00:00:00 1970 From: Konrad Rzeszutek Wilk Subject: Re: [PATCH 2/6] xen-netfront: reduce gso_max_size to account for ethernet header Date: Mon, 25 Mar 2013 12:56:37 -0400 Message-ID: <20130325165637.GA25740@phenom.dumpdata.com> References: <1364209702-12437-1-git-send-email-wei.liu2@citrix.com> <1364209702-12437-3-git-send-email-wei.liu2@citrix.com> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Cc: xen-devel@lists.xen.org, netdev@vger.kernel.org, ian.campbell@citrix.com, annie.li@oracle.com, david.vrabel@citrix.com To: Wei Liu Return-path: Received: from aserp1040.oracle.com ([141.146.126.69]:17429 "EHLO aserp1040.oracle.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S932748Ab3CYQ4q (ORCPT ); Mon, 25 Mar 2013 12:56:46 -0400 Content-Disposition: inline In-Reply-To: <1364209702-12437-3-git-send-email-wei.liu2@citrix.com> Sender: netdev-owner@vger.kernel.org List-ID: On Mon, Mar 25, 2013 at 11:08:18AM +0000, Wei Liu wrote: > 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. > Should it also CC stable@vger.kernel.org? > 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 >