From mboxrd@z Thu Jan 1 00:00:00 1970 From: "Jan Beulich" Subject: Re: [PATCH] xen-netfront: drop skb when skb->len > 65535 Date: Fri, 01 Mar 2013 16:48:06 +0000 Message-ID: <5130E9D602000078000C27CC@nat28.tlf.novell.com> References: <1362155488-24316-1-git-send-email-wei.liu2@citrix.com> Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Return-path: In-Reply-To: <1362155488-24316-1-git-send-email-wei.liu2@citrix.com> Content-Disposition: inline List-Unsubscribe: , List-Post: List-Help: List-Subscribe: , Sender: xen-devel-bounces@lists.xen.org Errors-To: xen-devel-bounces@lists.xen.org To: Wei Liu Cc: ij@2013.bluespice.org, ian.campbell@citrix.com, konrad.wilk@citrix.com, npegg@linode.com, xen-devel@lists.xen.org, annie.li@oracle.com List-Id: xen-devel@lists.xenproject.org >>> On 01.03.13 at 17:31, Wei Liu wrote: > The `size' field of Xen network wired format is uint16_t, anything bigger > than > 65535 will cause overflow. > > The punishment introduced by XSA-39 is quite harsh - DomU is disconnected when > it's discovered to be sending corrupted skbs. However, it looks like Linux > kernel will generate some bad skbs sometimes, so drop those skbs before > sending to over netback to avoid being disconnected. While fixing the frontend is certainly desirable, we can't expect everyone to deploy fixed netfronts in all their VMs - some OS versions used in there may even be out of service. So we ought to find a way to also more gracefully deal with the situation in netback, without re-opening the security issue that prompted those changes. Jan