[NET]: Fix fib_rules dump race

fib_rules_dump needs to use list_for_each_entry_rcu to protect against
concurrent changes to the rules list.

Signed-off-by: Patrick McHardy <kaber@trash.net>
diff --git a/net/core/fib_rules.c b/net/core/fib_rules.c
index 215f1bf..3aea4e8 100644
--- a/net/core/fib_rules.c
+++ b/net/core/fib_rules.c
@@ -374,7 +374,7 @@ int fib_rules_dump(struct sk_buff *skb, struct netlink_callback *cb, int family)
 		return -EAFNOSUPPORT;
 
 	rcu_read_lock();
-	list_for_each_entry(rule, ops->rules_list, list) {
+	list_for_each_entry_rcu(rule, ops->rules_list, list) {
 		if (idx < cb->args[0])
 			goto skip;