[ovs-dev] Kernel BUG on Xen

Nick Couchman Nick.Couchman at seakr.com
Thu Apr 22 18:38:10 UTC 2010

>  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?

The system works fine when I'm using the native Linux bridge support, it's just with OVS that it crashes.  In Windows, I'm using James Harper's GPL PV drivers for Xen guests, so it's possible there is something in the GPL PV driver code that is generating a short packet.  Yes, this is extremely consistent - I tried several times in a row and always got just to the Windows login screen before I see the Kernel BUG message that I initially posted.  The kernel BUG message is very consistent, too - always to the same function with the same traceback.


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