batman-adv: Fix broadcast packet CRC calculation

So far the crc16 checksum for a batman-adv broadcast data packet, received
on a batman-adv hard interface, was calculated over zero bytes of its
content leading to many incoming broadcast data packets wrongly being
dropped (60-80% packet loss).

This patch fixes this issue by calculating the crc16 over the actual,
complete broadcast payload.

The issue is a regression introduced by
("batman-adv: add broadcast duplicate check").

Signed-off-by: Linus Lüssing <linus.luessing@web.de>
Acked-by: Simon Wunderlich <siwu@hrz.tu-chemnitz.de>
Signed-off-by: Marek Lindner <lindner_marek@yahoo.de>

diff --git a/net/batman-adv/bridge_loop_avoidance.c b/net/batman-adv/bridge_loop_avoidance.c
index 0a9084ad19a60f71a2f9f70a8879e7ada24ccf6c..eebab20c7478c1d2e694ec37ec79b2ab1a8129e5 100644 (file)
--- a/net/batman-adv/bridge_loop_avoidance.c
+++ b/net/batman-adv/bridge_loop_avoidance.c
@@ -1210,8 +1210,8 @@ int batadv_bla_init(struct batadv_priv *bat_priv)
 /**
  * batadv_bla_check_bcast_duplist
  * @bat_priv: the bat priv with all the soft interface information
- * @bcast_packet: originator mac address
- * @hdr_size: maximum length of the frame
+ * @bcast_packet: encapsulated broadcast frame plus batman header
+ * @bcast_packet_len: length of encapsulated broadcast frame plus batman header
  *
  * check if it is on our broadcast list. Another gateway might
  * have sent the same packet because it is connected to the same backbone,
@@ -1224,14 +1224,14 @@ int batadv_bla_init(struct batadv_priv *bat_priv)
  */
 int batadv_bla_check_bcast_duplist(struct batadv_priv *bat_priv,
                                   struct batadv_bcast_packet *bcast_packet,
-                                  int hdr_size)
+                                  int bcast_packet_len)
 {
        int i, length, curr;
        uint8_t *content;
        uint16_t crc;
        struct batadv_bcast_duplist_entry *entry;
 
-       length = hdr_size - sizeof(*bcast_packet);
+       length = bcast_packet_len - sizeof(*bcast_packet);
        content = (uint8_t *)bcast_packet;
        content += sizeof(*bcast_packet);
 

diff --git a/net/batman-adv/routing.c b/net/batman-adv/routing.c
index 939fc01371dff0c209665b297b69ec6502887b1a..376b4cc6ca821ffb4279e2b4df81e61899be038f 100644 (file)
--- a/net/batman-adv/routing.c
+++ b/net/batman-adv/routing.c
@@ -1124,8 +1124,14 @@ int batadv_recv_bcast_packet(struct sk_buff *skb,
 
        spin_unlock_bh(&orig_node->bcast_seqno_lock);
 
+       /* keep skb linear for crc calculation */
+       if (skb_linearize(skb) < 0)
+               goto out;
+
+       bcast_packet = (struct batadv_bcast_packet *)skb->data;
+
        /* check whether this has been sent by another originator before */
-       if (batadv_bla_check_bcast_duplist(bat_priv, bcast_packet, hdr_size))
+       if (batadv_bla_check_bcast_duplist(bat_priv, bcast_packet, skb->len))
                goto out;
 
        /* rebroadcast packet */