From mboxrd@z Thu Jan 1 00:00:00 1970 From: Ian Campbell Subject: Re: [Xen-devel] [PATCH 2/4] xen-netfront: drop skb when skb->len > 65535 Date: Mon, 18 Mar 2013 13:48:20 +0000 Message-ID: <1363614500.30193.47.camel@zakaz.uk.xensource.com> References: <1363602955-24790-1-git-send-email-wei.liu2@citrix.com> <1363602955-24790-3-git-send-email-wei.liu2@citrix.com> <51471AAC.2050509@citrix.com> Mime-Version: 1.0 Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: 7bit Cc: Wei Liu , "netdev@vger.kernel.org" , "xen-devel@lists.xen.org" , "annie.li@oracle.com" , "konrad.wilk@oracle.com" To: David Vrabel Return-path: Received: from smtp.eu.citrix.com ([46.33.159.39]:60549 "EHLO SMTP.EU.CITRIX.COM" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753015Ab3CRNsX (ORCPT ); Mon, 18 Mar 2013 09:48:23 -0400 In-Reply-To: <51471AAC.2050509@citrix.com> Sender: netdev-owner@vger.kernel.org List-ID: On Mon, 2013-03-18 at 13:46 +0000, David Vrabel wrote: > On 18/03/13 10:35, Wei Liu wrote: > > The `size' field of Xen network wire format is uint16_t, anything bigger than > > 65535 will cause overflow. > > The backend needs to be able to handle these bad packets without > disconnecting the VIF -- we can't fix all the frontend drivers. Agreed, although that doesn't imply that we shouldn't fix the frontend where we can -- such as upstream as Wei does here. Ian. > > David > > > Signed-off-by: Wei Liu > > --- > > drivers/net/xen-netfront.c | 12 ++++++++++++ > > 1 file changed, 12 insertions(+) > > > > diff --git a/drivers/net/xen-netfront.c b/drivers/net/xen-netfront.c > > index 5527663..8c3d065 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 (unlikely(skb->len > (uint16_t)(~0))) { > > + net_alert_ratelimited( > > + "xennet: skb->len = %d, 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)) { >