batman-adv: Correct rcu refcounting for orig_node

It might be possible that 2 threads access the same data in the same
rcu grace period. The first thread calls call_rcu() to decrement the
refcount and free the data while the second thread increases the
refcount to use the data. To avoid this race condition all refcount
operations have to be atomic.

Reported-by: Sven Eckelmann <sven@narfation.org>
Signed-off-by: Marek Lindner <lindner_marek@yahoo.de>

1 files changed, 12 insertions, 12 deletions

diff --git a/net/batman-adv/routing.c b/net/batman-adv/routing.c
index fc4c12a049da..9863c03a2137 100644
--- a/net/batman-adv/routing.c
+++ b/net/batman-adv/routing.c
@@ -420,7 +420,7 @@ static void update_orig(struct bat_priv *bat_priv,
                 neigh_node = create_neighbor(orig_node, orig_tmp,
                                              ethhdr->h_source, if_incoming);
 
-                kref_put(&orig_tmp->refcount, orig_node_free_ref);
+                orig_node_free_ref(orig_tmp);
                 if (!neigh_node)
                         goto unlock;
 
@@ -604,7 +604,7 @@ static char count_real_packets(struct ethhdr *ethhdr,
 
 out:
         spin_unlock_bh(&orig_node->ogm_cnt_lock);
-        kref_put(&orig_node->refcount, orig_node_free_ref);
+        orig_node_free_ref(orig_node);
         return ret;
 }
 
@@ -730,7 +730,7 @@ void receive_bat_packet(struct ethhdr *ethhdr,
 
                 bat_dbg(DBG_BATMAN, bat_priv, "Drop packet: "
                         "originator packet from myself (via neighbor)\n");
-                kref_put(&orig_neigh_node->refcount, orig_node_free_ref);
+                orig_node_free_ref(orig_neigh_node);
                 return;
         }
 
@@ -835,10 +835,10 @@ void receive_bat_packet(struct ethhdr *ethhdr,
                                 0, hna_buff_len, if_incoming);
 
 out_neigh:
-        if (!is_single_hop_neigh)
-                kref_put(&orig_neigh_node->refcount, orig_node_free_ref);
+        if ((orig_neigh_node) && (!is_single_hop_neigh))
+                orig_node_free_ref(orig_neigh_node);
 out:
-        kref_put(&orig_node->refcount, orig_node_free_ref);
+        orig_node_free_ref(orig_node);
 }
 
 int recv_bat_packet(struct sk_buff *skb, struct batman_if *batman_if)
@@ -952,7 +952,7 @@ out:
         if (neigh_node)
                 neigh_node_free_ref(neigh_node);
         if (orig_node)
-                kref_put(&orig_node->refcount, orig_node_free_ref);
+                orig_node_free_ref(orig_node);
         return ret;
 }
 
@@ -1028,7 +1028,7 @@ out:
         if (neigh_node)
                 neigh_node_free_ref(neigh_node);
         if (orig_node)
-                kref_put(&orig_node->refcount, orig_node_free_ref);
+                orig_node_free_ref(orig_node);
         return ret;
 }
 
@@ -1134,7 +1134,7 @@ out:
         if (neigh_node)
                 neigh_node_free_ref(neigh_node);
         if (orig_node)
-                kref_put(&orig_node->refcount, orig_node_free_ref);
+                orig_node_free_ref(orig_node);
         return ret;
 }
 
@@ -1189,7 +1189,7 @@ struct neigh_node *find_router(struct bat_priv *bat_priv,
                 if (!primary_orig_node)
                         goto return_router;
 
-                kref_put(&primary_orig_node->refcount, orig_node_free_ref);
+                orig_node_free_ref(primary_orig_node);
         }
 
         /* with less than 2 candidates, we can't do any
@@ -1401,7 +1401,7 @@ out:
         if (neigh_node)
                 neigh_node_free_ref(neigh_node);
         if (orig_node)
-                kref_put(&orig_node->refcount, orig_node_free_ref);
+                orig_node_free_ref(orig_node);
         return ret;
 }
 
@@ -1543,7 +1543,7 @@ spin_unlock:
         spin_unlock_bh(&bat_priv->orig_hash_lock);
 out:
         if (orig_node)
-                kref_put(&orig_node->refcount, orig_node_free_ref);
+                orig_node_free_ref(orig_node);
         return ret;
 }