The backport seems reasonable IMO.

Is this tested in a multihost environment?.

I ask, because given the Ian explanation (which probably I got wrong), the 
issue is in the  
NET->NIC->VM path while the patch fixes the path in the network node (this is 
ran in the
dhcp agent). dhcp->NIC->NET.


Best,
Miguel Ángel Ajo


On Tuesday, 2 de June de 2015 at 9:32, Ian Wells wrote:

> The fix should work fine.  It is technically a workaround for the way 
> checksums work in virtualised systems, and the unfortunate fact that some 
> DHCP clients check checksums on packets where the hardware has checksum 
> offload enabled.  (This doesn't work due to an optimisation in the way QEMU 
> treats packet checksums.  You'll see the problem if your machine is running 
> the VM on the same host as its DHCP server and the VM has a vulnerable 
> client.)
>  
> I haven't tried it myself but I have confidence in it and would recommend a 
> backport.
> --  
> Ian.
>  
> On 1 June 2015 at 21:32, Kevin Benton <[email protected] 
> (mailto:[email protected])> wrote:
> > I would propose a back-port of it and then continue the discussion on the 
> > patch. I don't see any major blockers for back-porting it.
> >  
> > On Mon, Jun 1, 2015 at 7:01 PM, Tidwell, Ryan <[email protected] 
> > (mailto:[email protected])> wrote:
> > > Not seeing this on Kilo, we're seeing this on Juno builds (that's 
> > > expected).  I'm interested in a Juno backport, but mainly wanted to be 
> > > see if others had confidence in the fix.  The discussion in the bug 
> > > report also seemed to indicate there were other alternative solutions 
> > > others might be looking into that didn't involve an iptables rule.
> > >  
> > > -Ryan
> > >  
> > > -----Original Message-----
> > > From: Mark McClain [mailto:[email protected]]
> > > Sent: Monday, June 01, 2015 6:47 PM
> > > To: OpenStack Development Mailing List (not for usage questions)
> > > Subject: Re: [openstack-dev] [Neutron] virtual machine can not get DHCP 
> > > lease due packet has no checksum
> > >  
> > >  
> > > > On Jun 1, 2015, at 7:26 PM, Tidwell, Ryan <[email protected] 
> > > > (mailto:[email protected])> wrote:
> > > >
> > > > I see a fix for https://bugs.launchpad.net/neutron/+bug/1244589 merged 
> > > > during Kilo.  I'm wondering if we think we have identified a root cause 
> > > > and have merged an appropriate long-term fix, or if 
> > > > https://review.openstack.org/148718 was merged just so there's at least 
> > > > a fix available while we investigate other alternatives.  Does anyone 
> > > > have an update to provide?
> > > >
> > > > -Ryan
> > >  
> > > The fix works in environments we’ve tested in.  Are you still seeing 
> > > problems?
> > >  
> > > mark
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> >  
> > --  
> > Kevin Benton  
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