batman-adv: update data pointers after skb_cow()

batadv_check_unicast_ttvn() calls skb_cow(), so pointers into the SKB data
must be (re)set after calling it. The ethhdr variable is dropped
altogether.

Fixes: 7cdcf6dddc42 ("batman-adv: add UNICAST_4ADDR packet type")
Signed-off-by: Matthias Schiffer <mschiffer@universe-factory.net>
Signed-off-by: Sven Eckelmann <sven@narfation.org>
Signed-off-by: Simon Wunderlich <sw@simonwunderlich.de>

diff --git a/net/batman-adv/routing.c b/net/batman-adv/routing.c
index b6891e8b741c424496c58a21944f5bf30cff02ff..6a9242658c8d59c1cedac04f65f086149e5ebafe 100644 (file)
--- a/net/batman-adv/routing.c
+++ b/net/batman-adv/routing.c
@@ -968,14 +968,10 @@ int batadv_recv_unicast_packet(struct sk_buff *skb,
        struct batadv_orig_node *orig_node = NULL, *orig_node_gw = NULL;
        int check, hdr_size = sizeof(*unicast_packet);
        enum batadv_subtype subtype;
-       struct ethhdr *ethhdr;
        int ret = NET_RX_DROP;
        bool is4addr, is_gw;
 
        unicast_packet = (struct batadv_unicast_packet *)skb->data;
-       unicast_4addr_packet = (struct batadv_unicast_4addr_packet *)skb->data;
-       ethhdr = eth_hdr(skb);
-
        is4addr = unicast_packet->packet_type == BATADV_UNICAST_4ADDR;
        /* the caller function should have already pulled 2 bytes */
        if (is4addr)
@@ -995,12 +991,14 @@ int batadv_recv_unicast_packet(struct sk_buff *skb,
        if (!batadv_check_unicast_ttvn(bat_priv, skb, hdr_size))
                goto free_skb;
 
+       unicast_packet = (struct batadv_unicast_packet *)skb->data;
+
        /* packet for me */
        if (batadv_is_my_mac(bat_priv, unicast_packet->dest)) {
                /* If this is a unicast packet from another backgone gw,
                 * drop it.
                 */
-               orig_addr_gw = ethhdr->h_source;
+               orig_addr_gw = eth_hdr(skb)->h_source;
                orig_node_gw = batadv_orig_hash_find(bat_priv, orig_addr_gw);
                if (orig_node_gw) {
                        is_gw = batadv_bla_is_backbone_gw(skb, orig_node_gw,
@@ -1015,6 +1013,8 @@ int batadv_recv_unicast_packet(struct sk_buff *skb,
                }
 
                if (is4addr) {
+                       unicast_4addr_packet =
+                               (struct batadv_unicast_4addr_packet *)skb->data;
                        subtype = unicast_4addr_packet->subtype;
                        batadv_dat_inc_counter(bat_priv, subtype);