Included changes:

- fix soft-interface MTU computation
 - fix bogus pointer mangling when parsing the TT-TVLV
   container. This bug led to a wrong memory access.
 - fix memory leak by properly releasing the VLAN object
   after CRC check
 - properly check pskb_may_pull() return value
 - avoid potential race condition while adding new neighbour
 - fix potential memory leak by removing all the references
   to the orig_node object in case of initialization failure
 - fix the TT CRC computation by ensuring that every node uses
   the same byte order when hosts with different endianess are
   part of the same network
 - fix severe memory leak by freeing skb after a successful
   TVLV parsing
 - avoid potential double free when orig_node initialization
   fails
 - fix potential kernel paging error caused by the usage of
   the old value of skb->data after skb reallocation
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Merge tag 'batman-adv-fix-for-davem' of git://git.open-mesh.org/linux-merge

Included changes:
- fix soft-interface MTU computation
- fix bogus pointer mangling when parsing the TT-TVLV
  container. This bug led to a wrong memory access.
- fix memory leak by properly releasing the VLAN object
  after CRC check
- properly check pskb_may_pull() return value
- avoid potential race condition while adding new neighbour
- fix potential memory leak by removing all the references
  to the orig_node object in case of initialization failure
- fix the TT CRC computation by ensuring that every node uses
  the same byte order when hosts with different endianess are
  part of the same network
- fix severe memory leak by freeing skb after a successful
  TVLV parsing
- avoid potential double free when orig_node initialization
  fails
- fix potential kernel paging error caused by the usage of
  the old value of skb->data after skb reallocation

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

net/batman-adv/bat_iv_ogm.c

@@ -241,19 +241,19 @@ batadv_iv_ogm_orig_get(struct batadv_priv *bat_priv, const uint8_t *addr)
 	size = bat_priv->num_ifaces * sizeof(uint8_t);
 	orig_node->bat_iv.bcast_own_sum = kzalloc(size, GFP_ATOMIC);
 	if (!orig_node->bat_iv.bcast_own_sum)
-		goto free_bcast_own;
+		goto free_orig_node;
 
 	hash_added = batadv_hash_add(bat_priv->orig_hash, batadv_compare_orig,
 				     batadv_choose_orig, orig_node,
 				     &orig_node->hash_entry);
 	if (hash_added != 0)
-		goto free_bcast_own;
+		goto free_orig_node;
 
 	return orig_node;
 
-free_bcast_own:
-	kfree(orig_node->bat_iv.bcast_own);
 free_orig_node:
+	/* free twice, as batadv_orig_node_new sets refcount to 2 */
+	batadv_orig_node_free_ref(orig_node);
 	batadv_orig_node_free_ref(orig_node);
 
 	return NULL;
@@ -266,7 +266,7 @@ batadv_iv_ogm_neigh_new(struct batadv_hard_iface *hard_iface,
 			struct batadv_orig_node *orig_neigh)
 {
 	struct batadv_priv *bat_priv = netdev_priv(hard_iface->soft_iface);
-	struct batadv_neigh_node *neigh_node;
+	struct batadv_neigh_node *neigh_node, *tmp_neigh_node;
 
 	neigh_node = batadv_neigh_node_new(hard_iface, neigh_addr, orig_node);
 	if (!neigh_node)
@@ -281,14 +281,24 @@ batadv_iv_ogm_neigh_new(struct batadv_hard_iface *hard_iface,
 	neigh_node->orig_node = orig_neigh;
 	neigh_node->if_incoming = hard_iface;
 
-	batadv_dbg(BATADV_DBG_BATMAN, bat_priv,
-		   "Creating new neighbor %pM for orig_node %pM on interface %s\n",
-		   neigh_addr, orig_node->orig, hard_iface->net_dev->name);
-
 	spin_lock_bh(&orig_node->neigh_list_lock);
-	hlist_add_head_rcu(&neigh_node->list, &orig_node->neigh_list);
+	tmp_neigh_node = batadv_neigh_node_get(orig_node, hard_iface,
+					       neigh_addr);
+	if (!tmp_neigh_node) {
+		hlist_add_head_rcu(&neigh_node->list, &orig_node->neigh_list);
+	} else {
+		kfree(neigh_node);
+		batadv_hardif_free_ref(hard_iface);
+		neigh_node = tmp_neigh_node;
+	}
 	spin_unlock_bh(&orig_node->neigh_list_lock);
 
+	if (!tmp_neigh_node)
+		batadv_dbg(BATADV_DBG_BATMAN, bat_priv,
+			   "Creating new neighbor %pM for orig_node %pM on interface %s\n",
+			   neigh_addr, orig_node->orig,
+			   hard_iface->net_dev->name);
+
 out:
 	return neigh_node;
 }

net/batman-adv/hard-interface.c

@@ -241,7 +241,7 @@ int batadv_hardif_min_mtu(struct net_device *soft_iface)
 {
 	struct batadv_priv *bat_priv = netdev_priv(soft_iface);
 	const struct batadv_hard_iface *hard_iface;
-	int min_mtu = ETH_DATA_LEN;
+	int min_mtu = INT_MAX;
 
 	rcu_read_lock();
 	list_for_each_entry_rcu(hard_iface, &batadv_hardif_list, list) {
@@ -256,8 +256,6 @@ int batadv_hardif_min_mtu(struct net_device *soft_iface)
 	}
 	rcu_read_unlock();
 
-	atomic_set(&bat_priv->packet_size_max, min_mtu);
-
 	if (atomic_read(&bat_priv->fragmentation) == 0)
 		goto out;
 
@@ -268,13 +266,21 @@ int batadv_hardif_min_mtu(struct net_device *soft_iface)
 	min_mtu = min_t(int, min_mtu, BATADV_FRAG_MAX_FRAG_SIZE);
 	min_mtu -= sizeof(struct batadv_frag_packet);
 	min_mtu *= BATADV_FRAG_MAX_FRAGMENTS;
-	atomic_set(&bat_priv->packet_size_max, min_mtu);
-
-	/* with fragmentation enabled we can fragment external packets easily */
-	min_mtu = min_t(int, min_mtu, ETH_DATA_LEN);
 
 out:
-	return min_mtu - batadv_max_header_len();
+	/* report to the other components the maximum amount of bytes that
+	 * batman-adv can send over the wire (without considering the payload
+	 * overhead). For example, this value is used by TT to compute the
+	 * maximum local table table size
+	 */
+	atomic_set(&bat_priv->packet_size_max, min_mtu);
+
+	/* the real soft-interface MTU is computed by removing the payload
+	 * overhead from the maximum amount of bytes that was just computed.
+	 *
+	 * However batman-adv does not support MTUs bigger than ETH_DATA_LEN
+	 */
+	return min_t(int, min_mtu - batadv_max_header_len(), ETH_DATA_LEN);
 }
 
 /* adjusts the MTU if a new interface with a smaller MTU appeared. */

net/batman-adv/originator.c

@@ -457,6 +457,42 @@ out:
 	return neigh_node;
 }
 
+/**
+ * batadv_neigh_node_get - retrieve a neighbour from the list
+ * @orig_node: originator which the neighbour belongs to
+ * @hard_iface: the interface where this neighbour is connected to
+ * @addr: the address of the neighbour
+ *
+ * Looks for and possibly returns a neighbour belonging to this originator list
+ * which is connected through the provided hard interface.
+ * Returns NULL if the neighbour is not found.
+ */
+struct batadv_neigh_node *
+batadv_neigh_node_get(const struct batadv_orig_node *orig_node,
+		      const struct batadv_hard_iface *hard_iface,
+		      const uint8_t *addr)
+{
+	struct batadv_neigh_node *tmp_neigh_node, *res = NULL;
+
+	rcu_read_lock();
+	hlist_for_each_entry_rcu(tmp_neigh_node, &orig_node->neigh_list, list) {
+		if (!batadv_compare_eth(tmp_neigh_node->addr, addr))
+			continue;
+
+		if (tmp_neigh_node->if_incoming != hard_iface)
+			continue;
+
+		if (!atomic_inc_not_zero(&tmp_neigh_node->refcount))
+			continue;
+
+		res = tmp_neigh_node;
+		break;
+	}
+	rcu_read_unlock();
+
+	return res;
+}
+
 /**
  * batadv_orig_ifinfo_free_rcu - free the orig_ifinfo object
  * @rcu: rcu pointer of the orig_ifinfo object

net/batman-adv/originator.h

@@ -29,6 +29,10 @@ void batadv_orig_node_free_ref_now(struct batadv_orig_node *orig_node);
 struct batadv_orig_node *batadv_orig_node_new(struct batadv_priv *bat_priv,
 					      const uint8_t *addr);
 struct batadv_neigh_node *
+batadv_neigh_node_get(const struct batadv_orig_node *orig_node,
+		      const struct batadv_hard_iface *hard_iface,
+		      const uint8_t *addr);
+struct batadv_neigh_node *
 batadv_neigh_node_new(struct batadv_hard_iface *hard_iface,
 		      const uint8_t *neigh_addr,
 		      struct batadv_orig_node *orig_node);

net/batman-adv/routing.c

@@ -688,7 +688,7 @@ static int batadv_check_unicast_ttvn(struct batadv_priv *bat_priv,
 	int is_old_ttvn;
 
 	/* check if there is enough data before accessing it */
-	if (pskb_may_pull(skb, hdr_len + ETH_HLEN) < 0)
+	if (!pskb_may_pull(skb, hdr_len + ETH_HLEN))
 		return 0;
 
 	/* create a copy of the skb (in case of for re-routing) to modify it. */
@@ -918,6 +918,8 @@ int batadv_recv_unicast_tvlv(struct sk_buff *skb,
 
 	if (ret != NET_RX_SUCCESS)
 		ret = batadv_route_unicast_packet(skb, recv_if);
+	else
+		consume_skb(skb);
 
 	return ret;
 }

net/batman-adv/send.c

@@ -254,9 +254,9 @@ static int batadv_send_skb_unicast(struct batadv_priv *bat_priv,
 				   struct batadv_orig_node *orig_node,
 				   unsigned short vid)
 {
-	struct ethhdr *ethhdr = (struct ethhdr *)skb->data;
+	struct ethhdr *ethhdr;
 	struct batadv_unicast_packet *unicast_packet;
-	int ret = NET_XMIT_DROP;
+	int ret = NET_XMIT_DROP, hdr_size;
 
 	if (!orig_node)
 		goto out;
@@ -265,12 +265,16 @@ static int batadv_send_skb_unicast(struct batadv_priv *bat_priv,
 	case BATADV_UNICAST:
 		if (!batadv_send_skb_prepare_unicast(skb, orig_node))
 			goto out;
+
+		hdr_size = sizeof(*unicast_packet);
 		break;
 	case BATADV_UNICAST_4ADDR:
 		if (!batadv_send_skb_prepare_unicast_4addr(bat_priv, skb,
 							   orig_node,
 							   packet_subtype))
 			goto out;
+
+		hdr_size = sizeof(struct batadv_unicast_4addr_packet);
 		break;
 	default:
 		/* this function supports UNICAST and UNICAST_4ADDR only. It
@@ -279,6 +283,7 @@ static int batadv_send_skb_unicast(struct batadv_priv *bat_priv,
 		goto out;
 	}
 
+	ethhdr = (struct ethhdr *)(skb->data + hdr_size);
 	unicast_packet = (struct batadv_unicast_packet *)skb->data;
 
 	/* inform the destination node that we are still missing a correct route

net/batman-adv/translation-table.c

@@ -1975,6 +1975,7 @@ static uint32_t batadv_tt_global_crc(struct batadv_priv *bat_priv,
 	struct hlist_head *head;
 	uint32_t i, crc_tmp, crc = 0;
 	uint8_t flags;
+	__be16 tmp_vid;
 
 	for (i = 0; i < hash->size; i++) {
 		head = &hash->table[i];
@@ -2011,8 +2012,11 @@ static uint32_t batadv_tt_global_crc(struct batadv_priv *bat_priv,
 							     orig_node))
 				continue;
 
-			crc_tmp = crc32c(0, &tt_common->vid,
-					 sizeof(tt_common->vid));
+			/* use network order to read the VID: this ensures that
+			 * every node reads the bytes in the same order.
+			 */
+			tmp_vid = htons(tt_common->vid);
+			crc_tmp = crc32c(0, &tmp_vid, sizeof(tmp_vid));
 
 			/* compute the CRC on flags that have to be kept in sync
 			 * among nodes
@@ -2046,6 +2050,7 @@ static uint32_t batadv_tt_local_crc(struct batadv_priv *bat_priv,
 	struct hlist_head *head;
 	uint32_t i, crc_tmp, crc = 0;
 	uint8_t flags;
+	__be16 tmp_vid;
 
 	for (i = 0; i < hash->size; i++) {
 		head = &hash->table[i];
@@ -2064,8 +2069,11 @@ static uint32_t batadv_tt_local_crc(struct batadv_priv *bat_priv,
 			if (tt_common->flags & BATADV_TT_CLIENT_NEW)
 				continue;
 
-			crc_tmp = crc32c(0, &tt_common->vid,
-					 sizeof(tt_common->vid));
+			/* use network order to read the VID: this ensures that
+			 * every node reads the bytes in the same order.
+			 */
+			tmp_vid = htons(tt_common->vid);
+			crc_tmp = crc32c(0, &tmp_vid, sizeof(tmp_vid));
 
 			/* compute the CRC on flags that have to be kept in sync
 			 * among nodes
@@ -2262,6 +2270,7 @@ static bool batadv_tt_global_check_crc(struct batadv_orig_node *orig_node,
 {
 	struct batadv_tvlv_tt_vlan_data *tt_vlan_tmp;
 	struct batadv_orig_node_vlan *vlan;
+	uint32_t crc;
 	int i;
 
 	/* check if each received CRC matches the locally stored one */
@@ -2281,7 +2290,10 @@ static bool batadv_tt_global_check_crc(struct batadv_orig_node *orig_node,
 		if (!vlan)
 			return false;
 
-		if (vlan->tt.crc != ntohl(tt_vlan_tmp->crc))
+		crc = vlan->tt.crc;
+		batadv_orig_node_vlan_free_ref(vlan);
+
+		if (crc != ntohl(tt_vlan_tmp->crc))
 			return false;
 	}
 
@@ -3218,7 +3230,6 @@ static void batadv_tt_update_orig(struct batadv_priv *bat_priv,
 
 		spin_lock_bh(&orig_node->tt_lock);
 
-		tt_change = (struct batadv_tvlv_tt_change *)tt_buff;
 		batadv_tt_update_changes(bat_priv, orig_node, tt_num_changes,
 					 ttvn, tt_change);