batman-adv: fix potential kernel paging errors for unicast transmissions

[cascardo/linux.git] / net / batman-adv / unicast.c

diff --git a/net/batman-adv/unicast.c b/net/batman-adv/unicast.c
index dc8b5d4..688a041 100644 (file)
--- a/net/batman-adv/unicast.c
+++ b/net/batman-adv/unicast.c
@@ -326,7 +326,9 @@ static bool batadv_unicast_push_and_fill_skb(struct sk_buff *skb, int hdr_size,
  * @skb: the skb containing the payload to encapsulate
  * @orig_node: the destination node
  *
- * Returns false if the payload could not be encapsulated or true otherwise
+ * Returns false if the payload could not be encapsulated or true otherwise.
+ *
+ * This call might reallocate skb data.
  */
 static bool batadv_unicast_prepare_skb(struct sk_buff *skb,
                                       struct batadv_orig_node *orig_node)
@@ -343,7 +345,9 @@ static bool batadv_unicast_prepare_skb(struct sk_buff *skb,
  * @orig_node: the destination node
  * @packet_subtype: the batman 4addr packet subtype to use
  *
- * Returns false if the payload could not be encapsulated or true otherwise
+ * Returns false if the payload could not be encapsulated or true otherwise.
+ *
+ * This call might reallocate skb data.
  */
 bool batadv_unicast_4addr_prepare_skb(struct batadv_priv *bat_priv,
                                      struct sk_buff *skb,
@@ -401,7 +405,7 @@ int batadv_unicast_generic_send_skb(struct batadv_priv *bat_priv,
        struct batadv_neigh_node *neigh_node;
        int data_len = skb->len;
        int ret = NET_RX_DROP;
-       unsigned int dev_mtu;
+       unsigned int dev_mtu, header_len;
 
        /* get routing information */
        if (is_multicast_ether_addr(ethhdr->h_dest)) {
@@ -429,10 +433,12 @@ find_router:
        switch (packet_type) {
        case BATADV_UNICAST:
                batadv_unicast_prepare_skb(skb, orig_node);
+               header_len = sizeof(struct batadv_unicast_packet);
                break;
        case BATADV_UNICAST_4ADDR:
                batadv_unicast_4addr_prepare_skb(bat_priv, skb, orig_node,
                                                 packet_subtype);
+               header_len = sizeof(struct batadv_unicast_4addr_packet);
                break;
        default:
                /* this function supports UNICAST and UNICAST_4ADDR only. It
@@ -441,6 +447,7 @@ find_router:
                goto out;
        }
 
+       ethhdr = (struct ethhdr *)(skb->data + header_len);
        unicast_packet = (struct batadv_unicast_packet *)skb->data;
 
        /* inform the destination node that we are still missing a correct route