2019-05-14, 12:05:16 +0200, Nicolas Dichtel wrote:
> Le 14/05/2019 à 10:01, Sabrina Dubroca a écrit :
> > 2019-05-14, 09:32:32 +0200, Nicolas Dichtel wrote:
> [snip]
> >> What about this one?
> >> Fixes: d8a5ec672768 ("[NET]: netlink support for moving devices between
> >> network
> >> namespaces.")
> >
> > Nice. Now I think the bug can't really trigger unless one of these
> > commits are present:
> >
> > aa79e66eee5d ("net: Make ifindex generation per-net namespace")
> > 9c7dafbfab15 ("net: Allow to create links with given ifindex")
> >
> I don't think so.
>
> Please have a look to commit ce286d327341 ("[NET]: Implement network device
> movement between namespaces").
> In dev_change_net_namespace(), there is the following code:
>
> /* If there is an ifindex conflict assign a new one */
> if (__dev_get_by_index(net, dev->ifindex)) {
> int iflink = (dev->iflink == dev->ifindex);
> dev->ifindex = dev_new_index(net);
> if (iflink)
> dev->iflink = dev->ifindex;
> }
>
> This code may change the ifindex of an interface when this interface moves to
> another netns. This may happen even before the commits you propose, because
> the
> global ifindex counter can wrap around.
Yes, that's possible although quite unlikely. I'll go with d8a5ec672768.
--
Sabrina
