rtnetlink: Fix error handling in do_setlink()

Commit c02db8c6290bb992442fec1407643c94cc414375:

	Author:  Chris Wright <chrisw@sous-sol.org>
	Date:    Sun May 16 01:05:45 2010 -0700
	Subject: rtnetlink: make SR-IOV VF interface symmetric

adds broken error handling to do_setlink() in net/core/rtnetlink.c.  The
problem is the following chunk of code:

	if (tb[IFLA_VFINFO_LIST]) {
		struct nlattr *attr;
		int rem;
		nla_for_each_nested(attr, tb[IFLA_VFINFO_LIST], rem) {
			if (nla_type(attr) != IFLA_VF_INFO)
  ---->				goto errout;
			err = do_setvfinfo(dev, attr);
			if (err < 0)
				goto errout;
			modified = 1;
		}
	}

which can get to errout without setting err, resulting in the following error:

net/core/rtnetlink.c: In function 'do_setlink':
net/core/rtnetlink.c:904: warning: 'err' may be used uninitialized in this function

Change the code to return -EINVAL in this case.  Note that this might not be
the appropriate error though.

Signed-off-by: David Howells <dhowells@redhat.com>
cc: Chris Wright <chrisw@sous-sol.org>
cc: David S. Miller <davem@davemloft.net>
Acked-by: Chris Wright <chrisw@sous-sol.org>
Signed-off-by: David S. Miller <davem@davemloft.net>

net/core/rtnetlink.c

@@ -1199,8 +1199,10 @@ static int do_setlink(struct net_device *dev, struct ifinfomsg *ifm,
 		struct nlattr *attr;
 		int rem;
 		nla_for_each_nested(attr, tb[IFLA_VFINFO_LIST], rem) {
-			if (nla_type(attr) != IFLA_VF_INFO)
+			if (nla_type(attr) != IFLA_VF_INFO) {
+				err = -EINVAL;
 				goto errout;
+			}
 			err = do_setvfinfo(dev, attr);
 			if (err < 0)
 				goto errout;