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, 14 insertions, 5 deletions

diff --git a/net/batman-adv/icmp_socket.c b/net/batman-adv/icmp_socket.c
index 49079c254476..fa22ba2bb832 100644
--- a/net/batman-adv/icmp_socket.c
+++ b/net/batman-adv/icmp_socket.c
@@ -153,6 +153,7 @@ static ssize_t bat_socket_write(struct file *file, const char __user *buff,
 {
         struct socket_client *socket_client = file->private_data;
         struct bat_priv *bat_priv = socket_client->bat_priv;
+        struct hard_iface *primary_if = NULL;
         struct sk_buff *skb;
         struct icmp_packet_rr *icmp_packet;
 
@@ -167,15 +168,21 @@ static ssize_t bat_socket_write(struct file *file, const char __user *buff,
                 return -EINVAL;
         }
 
-        if (!bat_priv->primary_if)
-                return -EFAULT;
+        primary_if = primary_if_get_selected(bat_priv);
+
+        if (!primary_if) {
+                len = -EFAULT;
+                goto out;
+        }
 
         if (len >= sizeof(struct icmp_packet_rr))
                 packet_len = sizeof(struct icmp_packet_rr);
 
         skb = dev_alloc_skb(packet_len + sizeof(struct ethhdr));
-        if (!skb)
-                return -ENOMEM;
+        if (!skb) {
+                len = -ENOMEM;
+                goto out;
+        }
 
         skb_reserve(skb, sizeof(struct ethhdr));
         icmp_packet = (struct icmp_packet_rr *)skb_put(skb, packet_len);
@@ -233,7 +240,7 @@ static ssize_t bat_socket_write(struct file *file, const char __user *buff,
                 goto dst_unreach;
 
         memcpy(icmp_packet->orig,
-               bat_priv->primary_if->net_dev->dev_addr, ETH_ALEN);
+               primary_if->net_dev->dev_addr, ETH_ALEN);
 
         if (packet_len == sizeof(struct icmp_packet_rr))
                 memcpy(icmp_packet->rr,
@@ -248,6 +255,8 @@ dst_unreach:
 free_skb:
         kfree_skb(skb);
 out:
+        if (primary_if)
+                hardif_free_ref(primary_if);
         if (neigh_node)
                 neigh_node_free_ref(neigh_node);
         if (orig_node)