batman-adv: Make orig_node->router an rcu protected pointer

The rcu protected macros rcu_dereference() and rcu_assign_pointer()
for the orig_node->router need to be used, as well as spin/rcu locking.
Otherwise we might end up using a router pointer pointing to already
freed memory.

Therefore this commit introduces the safe getter method
orig_node_get_router().

Signed-off-by: Linus Lüssing <linus.luessing@web.de>
Signed-off-by: Marek Lindner <lindner_marek@yahoo.de>
Signed-off-by: Sven Eckelmann <sven@narfation.org>

1 files changed, 3 insertions, 15 deletions

diff --git a/net/batman-adv/icmp_socket.c b/net/batman-adv/icmp_socket.c
index 34ce56c358e5..49079c254476 100644
--- a/net/batman-adv/icmp_socket.c
+++ b/net/batman-adv/icmp_socket.c
@@ -218,23 +218,13 @@ static ssize_t bat_socket_write(struct file *file, const char __user *buff,
         if (atomic_read(&bat_priv->mesh_state) != MESH_ACTIVE)
                 goto dst_unreach;
 
-        rcu_read_lock();
         orig_node = orig_hash_find(bat_priv, icmp_packet->dst);
-
         if (!orig_node)
-                goto unlock;
-
-        neigh_node = orig_node->router;
+                goto dst_unreach;
 
+        neigh_node = orig_node_get_router(orig_node);
         if (!neigh_node)
-                goto unlock;
-
-        if (!atomic_inc_not_zero(&neigh_node->refcount)) {
-                neigh_node = NULL;
-                goto unlock;
-        }
-
-        rcu_read_unlock();
+                goto dst_unreach;
 
         if (!neigh_node->if_incoming)
                 goto dst_unreach;
@@ -252,8 +242,6 @@ static ssize_t bat_socket_write(struct file *file, const char __user *buff,
         send_skb_packet(skb, neigh_node->if_incoming, neigh_node->addr);
         goto out;
 
-unlock:
-        rcu_read_unlock();
 dst_unreach:
         icmp_packet->msg_type = DESTINATION_UNREACHABLE;
         bat_socket_add_packet(socket_client, icmp_packet, packet_len);