batman-adv: Increase orig_node refcount before releasing rcu read lock

When unicast_send_skb() is increasing the orig_node's refcount another
thread might have been freeing this orig_node already. We need to
increase the refcount in the rcu read lock protected area to avoid that.

Signed-off-by: Linus Lüssing <linus.luessing@ascom.ch>
Signed-off-by: Marek Lindner <lindner_marek@yahoo.de>

2 files changed, 5 insertions, 3 deletions

diff --git a/net/batman-adv/gateway_client.c b/net/batman-adv/gateway_client.c
index a3e842fd0f9c..41eba8a660f5 100644
--- a/net/batman-adv/gateway_client.c
+++ b/net/batman-adv/gateway_client.c
@@ -54,6 +54,9 @@ void *gw_get_selected(struct bat_priv *bat_priv)
 
         orig_node = curr_gateway_tmp->orig_node;
 
+        if (orig_node)
+                kref_get(&orig_node->refcount);
+
 out:
         rcu_read_unlock();
         return orig_node;
diff --git a/net/batman-adv/unicast.c b/net/batman-adv/unicast.c
index 7ca994ccac1d..0603ceaeef62 100644
--- a/net/batman-adv/unicast.c
+++ b/net/batman-adv/unicast.c
@@ -293,10 +293,9 @@ int unicast_send_skb(struct sk_buff *skb, struct bat_priv *bat_priv)
         spin_lock_bh(&bat_priv->orig_hash_lock);
 
         /* get routing information */
-        if (is_multicast_ether_addr(ethhdr->h_dest))
+        if (is_multicast_ether_addr(ethhdr->h_dest)) {
                 orig_node = (struct orig_node *)gw_get_selected(bat_priv);
-                if (orig_node) {
-                        kref_get(&orig_node->refcount);
+                if (orig_node)
                         goto find_router;
         }