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>

3 files changed, 27 insertions, 10 deletions

diff --git a/net/batman-adv/bridge_loop_avoidance.c b/net/batman-adv/bridge_loop_avoidance.c
index 0a9084ad19a6..fd8d5afec0dd 100644
--- a/net/batman-adv/bridge_loop_avoidance.c
+++ b/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;
 }
 
 
diff --git a/net/batman-adv/routing.c b/net/batman-adv/routing.c
index 939fc01371df..376b4cc6ca82 100644
--- 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 */
diff --git a/net/batman-adv/types.h b/net/batman-adv/types.h
index 2ed82caacdca..ac1e07a80454 100644
--- a/net/batman-adv/types.h
+++ b/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;
 };