fib:fix BUG_ON in fib_nl_newrule when add new fib rule

add new fib rule can cause BUG_ON happen
the reproduce shell is
ip rule add pref 38
ip rule add pref 38
ip rule add to 192.168.3.0/24 goto 38
ip rule del pref 38
ip rule add to 192.168.3.0/24 goto 38
ip rule add pref 38

then the BUG_ON will happen
del BUG_ON and use (ctarget == NULL) identify whether this rule is unresolved

Signed-off-by: Gao feng <gaofeng@cn.fujitsu.com>
Signed-off-by: Eric Dumazet <eric.dumazet@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

1 files changed, 2 insertions, 2 deletions

diff --git a/net/core/fib_rules.c b/net/core/fib_rules.c
index e7ab0c0285b5..3231b468bb72 100644
--- a/net/core/fib_rules.c
+++ b/net/core/fib_rules.c
@@ -384,8 +384,8 @@ static int fib_nl_newrule(struct sk_buff *skb, struct nlmsghdr* nlh, void *arg)
                  */
                 list_for_each_entry(r, &ops->rules_list, list) {
                         if (r->action == FR_ACT_GOTO &&
-                            r->target == rule->pref) {
-                                BUG_ON(rtnl_dereference(r->ctarget) != NULL);
+                            r->target == rule->pref &&
+                            rtnl_dereference(r->ctarget) == NULL) {
                                 rcu_assign_pointer(r->ctarget, rule);
                                 if (--ops->unresolved_rules == 0)
                                         break;