> On Fri, 16 Jun 2017 17:23:51 +0300
> Serhey Popovych <serhe.popov...@gmail.com> wrote:
>
>> Interface index is signed integer, we can pass ifm->ifi_index
>> from userspace via netlink and create network device with
>> negative ifindex value.
>>
>> Fixes: 9c7dafbfab15 ("net: Allow to create links with given ifindex")
>> Signed-off-by: Serhey Popovych <serhe.popov...@gmail.com>
>> ---
>> net/core/dev.c | 2 +-
>> 1 file changed, 1 insertion(+), 1 deletion(-)
>>
>> diff --git a/net/core/dev.c b/net/core/dev.c
>> index 8658074..dae8010 100644
>> --- a/net/core/dev.c
>> +++ b/net/core/dev.c
>> @@ -7491,7 +7491,7 @@ int register_netdevice(struct net_device *dev)
>> }
>>
>> ret = -EBUSY;
>> - if (!dev->ifindex)
>> + if (dev->ifindex <= 0)
>> dev->ifindex = dev_new_index(net);
>> else if (__dev_get_by_index(net, dev->ifindex))
>> goto err_uninit;
>
> You should fix this by adding error check in the netlink portion
> that allows creating devices with given ifindex. Passing < 0
> should be an error.But should this break some setups if I add such check to
> netlink
portion? In my opinion it is better to choose silently different
ifindex rather than reporting failure. That's why I prefer doing
this in register_netdevice().
Also there is similar problem for drivers/net/veth.c, it might
happen that other places will be added later that setup
dev->ifindex and then call register_netdevice().
What do you think?
Thanks for quick review!
>
--
Thanks, Serhey
