net: rtnetlink: Don't export empty RTAX_FEATURES

Since the features bit field has bits for internal only use as well, it
may happen that the kernel exports RTAX_FEATURES attribute with zero
value which is pointless.

Fix this by making sure the attribute is added only if the exported
value is non-zero.

Signed-off-by: Phil Sutter <phil@nwl.cc>
Signed-off-by: David S. Miller <davem@davemloft.net>

diff --git a/net/core/rtnetlink.c b/net/core/rtnetlink.c
index 189cc78..318fc52 100644 (file)
--- a/net/core/rtnetlink.c
+++ b/net/core/rtnetlink.c
@@ -704,6 +704,8 @@ int rtnetlink_put_metrics(struct sk_buff *skb, u32 *metrics)
                        } else if (i == RTAX_FEATURES - 1) {
                                u32 user_features = metrics[i] & RTAX_FEATURE_MASK;
 
+                               if (!user_features)
+                                       continue;
                                BUILD_BUG_ON(RTAX_FEATURE_MASK & DST_FEATURE_MASK);
                                if (nla_put_u32(skb, i + 1, user_features))
                                        goto nla_put_failure;