From mboxrd@z Thu Jan 1 00:00:00 1970 From: annie li Subject: Re: [Xen-devel] [PATCH 2/4] xen-netfront: drop skb when skb->len > 65535 Date: Tue, 19 Mar 2013 09:35:05 +0800 Message-ID: <5147C0C9.3040601@oracle.com> References: <1363602955-24790-1-git-send-email-wei.liu2@citrix.com> <1363602955-24790-3-git-send-email-wei.liu2@citrix.com> Mime-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit Cc: netdev@vger.kernel.org, xen-devel@lists.xen.org, ian.campbell@citrix.com, konrad.wilk@oracle.com To: Wei Liu Return-path: Received: from userp1040.oracle.com ([156.151.31.81]:32988 "EHLO userp1040.oracle.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754564Ab3CSBfQ (ORCPT ); Mon, 18 Mar 2013 21:35:16 -0400 In-Reply-To: <1363602955-24790-3-git-send-email-wei.liu2@citrix.com> Sender: netdev-owner@vger.kernel.org List-ID: On 2013-3-18 18:35, Wei Liu wrote: > The `size' field of Xen network wire format is uint16_t, anything bigger than > 65535 will cause overflow. > > 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; > + } > + Maybe it is better to do some segmentation for packets(>15536) which support segments, and drop those which do not support segment. This can also be implemented in another patch(Just like what i did for packets which requires slots larger than SKB_MAX_FRAGS). Thanks Annie > slots = DIV_ROUND_UP(offset + len, PAGE_SIZE) + > xennet_count_skb_frag_slots(skb); > if (unlikely(slots > MAX_SKB_FRAGS + 1)) {