Merge tag 'batman-adv-fix-for-davem' of git://git.open-mesh.org/linux-merge

Included fixes:
- Fix broadcast packet CRC calculation which can lead to ~80% broadcast packet
  loss
- Fix a race condition in duplicate broadcast packet check

Signed-off-by: David S. Miller <davem@davemloft.net>

net/batman-adv/bridge_loop_avoidance.c

@@ -1167,6 +1167,8 @@ int batadv_bla_init(struct batadv_priv *bat_priv)
 	uint16_t crc;
 	unsigned long entrytime;
 
+	spin_lock_init(&bat_priv->bla.bcast_duplist_lock);
+
 	batadv_dbg(BATADV_DBG_BLA, bat_priv, "bla hash registering\n");
 
 	/* setting claim destination address */
@@ -1210,8 +1212,8 @@ 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,
@@ -1224,20 +1226,22 @@ 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;
+	int i, length, curr, ret = 0;
 	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);
 
 	/* calculate the crc ... */
 	crc = crc16(0, content, length);
 
+	spin_lock_bh(&bat_priv->bla.bcast_duplist_lock);
+
 	for (i = 0; i < BATADV_DUPLIST_SIZE; i++) {
 		curr = (bat_priv->bla.bcast_duplist_curr + i);
 		curr %= BATADV_DUPLIST_SIZE;
@@ -1259,9 +1263,12 @@ int batadv_bla_check_bcast_duplist(struct batadv_priv *bat_priv,
 		/* this entry seems to match: same crc, not too old,
 		 * and from another gw. therefore return 1 to forbid it.
 		 */
-		return 1;
+		ret = 1;
+		goto out;
 	}
-	/* not found, add a new entry (overwrite the oldest entry) */
+	/* not found, add a new entry (overwrite the oldest entry)
+	 * and allow it, its the first occurence.
+	 */
 	curr = (bat_priv->bla.bcast_duplist_curr + BATADV_DUPLIST_SIZE - 1);
 	curr %= BATADV_DUPLIST_SIZE;
 	entry = &bat_priv->bla.bcast_duplist[curr];
@@ -1270,8 +1277,10 @@ int batadv_bla_check_bcast_duplist(struct batadv_priv *bat_priv,
 	memcpy(entry->orig, bcast_packet->orig, ETH_ALEN);
 	bat_priv->bla.bcast_duplist_curr = curr;
 
-	/* allow it, its the first occurence. */
-	return 0;
+out:
+	spin_unlock_bh(&bat_priv->bla.bcast_duplist_lock);
+
+	return ret;
 }
 
 

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 */

net/batman-adv/types.h

@@ -205,6 +205,8 @@ struct batadv_priv_bla {
 	struct batadv_hashtable *backbone_hash;
 	struct batadv_bcast_duplist_entry bcast_duplist[BATADV_DUPLIST_SIZE];
 	int bcast_duplist_curr;
+	/* protects bcast_duplist and bcast_duplist_curr */
+	spinlock_t bcast_duplist_lock;
 	struct batadv_bla_claim_dst claim_dest;
 	struct delayed_work work;
 };