batman-adv: Make bat_priv->primary_if an rcu protected pointer

The rcu protected macros rcu_dereference() and rcu_assign_pointer()
for the bat_priv->primary_if need to be used, as well as spin/rcu locking.

Otherwise we might end up using a primary_if pointer pointing to already
freed memory.

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

1 files changed, 13 insertions, 4 deletions

diff --git a/net/batman-adv/send.c b/net/batman-adv/send.c
index 7650e2bf187d..02b541a6dfef 100644
--- a/net/batman-adv/send.c
+++ b/net/batman-adv/send.c
@@ -244,6 +244,7 @@ static void rebuild_batman_packet(struct bat_priv *bat_priv,
 void schedule_own_packet(struct hard_iface *hard_iface)
 {
         struct bat_priv *bat_priv = netdev_priv(hard_iface->soft_iface);
+        struct hard_iface *primary_if;
         unsigned long send_time;
         struct batman_packet *batman_packet;
         int vis_server;
@@ -253,6 +254,7 @@ void schedule_own_packet(struct hard_iface *hard_iface)
                 return;
 
         vis_server = atomic_read(&bat_priv->vis_mode);
+        primary_if = primary_if_get_selected(bat_priv);
 
         /**
          * the interface gets activated here to avoid race conditions between
@@ -266,7 +268,7 @@ void schedule_own_packet(struct hard_iface *hard_iface)
 
         /* if local hna has changed and interface is a primary interface */
         if ((atomic_read(&bat_priv->hna_local_changed)) &&
-            (hard_iface == bat_priv->primary_if))
+            (hard_iface == primary_if))
                 rebuild_batman_packet(bat_priv, hard_iface);
 
         /**
@@ -284,7 +286,7 @@ void schedule_own_packet(struct hard_iface *hard_iface)
         else
                 batman_packet->flags &= ~VIS_SERVER;
 
-        if ((hard_iface == bat_priv->primary_if) &&
+        if ((hard_iface == primary_if) &&
             (atomic_read(&bat_priv->gw_mode) == GW_MODE_SERVER))
                 batman_packet->gw_flags =
                                 (uint8_t)atomic_read(&bat_priv->gw_bandwidth);
@@ -299,6 +301,9 @@ void schedule_own_packet(struct hard_iface *hard_iface)
                                hard_iface->packet_buff,
                                hard_iface->packet_len,
                                hard_iface, 1, send_time);
+
+        if (primary_if)
+                hardif_free_ref(primary_if);
 }
 
 void schedule_forward_packet(struct orig_node *orig_node,
@@ -403,6 +408,7 @@ static void _add_bcast_packet_to_list(struct bat_priv *bat_priv,
  * skb is freed. */
 int add_bcast_packet_to_list(struct bat_priv *bat_priv, struct sk_buff *skb)
 {
+        struct hard_iface *primary_if = NULL;
         struct forw_packet *forw_packet;
         struct bcast_packet *bcast_packet;
 
@@ -411,7 +417,8 @@ int add_bcast_packet_to_list(struct bat_priv *bat_priv, struct sk_buff *skb)
                 goto out;
         }
 
-        if (!bat_priv->primary_if)
+        primary_if = primary_if_get_selected(bat_priv);
+        if (!primary_if)
                 goto out;
 
         forw_packet = kmalloc(sizeof(struct forw_packet), GFP_ATOMIC);
@@ -430,7 +437,7 @@ int add_bcast_packet_to_list(struct bat_priv *bat_priv, struct sk_buff *skb)
         skb_reset_mac_header(skb);
 
         forw_packet->skb = skb;
-        forw_packet->if_incoming = bat_priv->primary_if;
+        forw_packet->if_incoming = primary_if;
 
         /* how often did we send the bcast packet ? */
         forw_packet->num_packets = 0;
@@ -443,6 +450,8 @@ packet_free:
 out_and_inc:
         atomic_inc(&bat_priv->bcast_queue_left);
 out:
+        if (primary_if)
+                hardif_free_ref(primary_if);
         return NETDEV_TX_BUSY;
 }