From mboxrd@z Thu Jan 1 00:00:00 1970 From: Stephen Hemminger Subject: Re: [PATCH 1/3] dev: Prevent creating network devices with negative ifindex Date: Fri, 16 Jun 2017 09:18:06 -0700 Message-ID: <20170616091806.2dd229e2@xeon-e3> References: Mime-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit Cc: netdev@vger.kernel.org To: Serhey Popovych Return-path: Received: from mail-pg0-f51.google.com ([74.125.83.51]:33821 "EHLO mail-pg0-f51.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751762AbdFPQSN (ORCPT ); Fri, 16 Jun 2017 12:18:13 -0400 Received: by mail-pg0-f51.google.com with SMTP id v18so22374762pgb.1 for ; Fri, 16 Jun 2017 09:18:13 -0700 (PDT) In-Reply-To: Sender: netdev-owner@vger.kernel.org List-ID: On Fri, 16 Jun 2017 17:23:51 +0300 Serhey Popovych 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 > --- > 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.