[ovs-dev] Kernel BUG on Xen

Jesse Gross jesse at nicira.com
Thu Apr 22 18:34:53 UTC 2010

On Thu, Apr 22, 2010 at 2:20 PM, Nick Couchman <Nick.Couchman at seakr.com>wrote:

> >
> > Were you able to verify that this was checksum related by turning off
> > checksum offloading in the guest kernel?
> >
> I booted Windows in Safe Mode, and disabled Checksum Offloading for the GPL
> PV drivers that I'm using.  Seems to be a lot happier, now - hasn't crashed,
> yet.  So, I'd say that, yes, the problem is checksum-related.

 It looks like we don't properly handle the case where the packet is shorter
than it should be, i.e. the length in the header indicates it is longer than
the actual data.

The interesting thing is that this should be checked in skb_pull_up_to(),
which we got directly from Xen, so at least some versions of Xen might have
the same issue.  Have you tried running without OVS?

Obviously, we should be handling all packets without crashing, valid or not,
but I'm a little surprised that Windows would generate such a packet.  Does
this happen consistently?  Is there anything interesting about the guest?
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