net: ncsi: fix a missing check for nla_nest_start

nla_nest_start may fail and thus deserves a check.

The fix returns -EMSGSIZE in case it fails.
Signed-off-by: Kangjie Lu <kjlu@umn.edu>
Signed-off-by: David S. Miller <davem@davemloft.net>

net/ncsi/ncsi-netlink.c

@@ -251,6 +251,10 @@ static int ncsi_pkg_info_all_nl(struct sk_buff *skb,
 	}
 
 	attr = nla_nest_start(skb, NCSI_ATTR_PACKAGE_LIST);
+	if (!attr) {
+		rc = -EMSGSIZE;
+		goto err;
+	}
 	rc = ncsi_write_package_info(skb, ndp, package->id);
 	if (rc) {
 		nla_nest_cancel(skb, attr);