batman-adv: increase orig refcount when storing ref in gw_node

A pointer to the orig_node representing a bat-gateway is
stored in the gw_node->orig_node member, but the refcount
for such orig_node is never increased.
This leads to memory faults when gw_node->orig_node is accessed
and the originator has already been freed.

Fix this by increasing the refcount on gw_node creation
and decreasing it on gw_node free.

Signed-off-by: Antonio Quartulli <antonio@open-mesh.com>
Signed-off-by: Marek Lindner <mareklindner@neomailbox.ch>

1 files changed, 9 insertions, 2 deletions

diff --git a/net/batman-adv/gateway_client.c b/net/batman-adv/gateway_client.c
index c835e137423b..90cff585b37d 100644
--- a/net/batman-adv/gateway_client.c
+++ b/net/batman-adv/gateway_client.c
@@ -42,8 +42,10 @@
 
 static void batadv_gw_node_free_ref(struct batadv_gw_node *gw_node)
 {
-        if (atomic_dec_and_test(&gw_node->refcount))
+        if (atomic_dec_and_test(&gw_node->refcount)) {
+                batadv_orig_node_free_ref(gw_node->orig_node);
                 kfree_rcu(gw_node, rcu);
+        }
 }
 
 static struct batadv_gw_node *
@@ -406,9 +408,14 @@ static void batadv_gw_node_add(struct batadv_priv *bat_priv,
         if (gateway->bandwidth_down == 0)
                 return;
 
+        if (!atomic_inc_not_zero(&orig_node->refcount))
+                return;
+
         gw_node = kzalloc(sizeof(*gw_node), GFP_ATOMIC);
-        if (!gw_node)
+        if (!gw_node) {
+                batadv_orig_node_free_ref(orig_node);
                 return;
+        }
 
         INIT_HLIST_NODE(&gw_node->list);
         gw_node->orig_node = orig_node;