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>

7 files changed, 101 insertions, 27 deletions

diff --git a/net/batman-adv/bat_iv_ogm.c b/net/batman-adv/bat_iv_ogm.c
index 512159bf607f..8323bced8e5b 100644
--- a/net/batman-adv/bat_iv_ogm.c
+++ b/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;
 }
diff --git a/net/batman-adv/hard-interface.c b/net/batman-adv/hard-interface.c
index 3d417d3641c6..b851cc580853 100644
--- a/net/batman-adv/hard-interface.c
+++ b/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. */
diff --git a/net/batman-adv/originator.c b/net/batman-adv/originator.c
index 6df12a2e3605..853941629dc1 100644
--- a/net/batman-adv/originator.c
+++ b/net/batman-adv/originator.c
@@ -458,6 +458,42 @@ out:
 }
 
 /**
+ * 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
  */
diff --git a/net/batman-adv/originator.h b/net/batman-adv/originator.h
index 37be290f63f6..db3a9ed734cb 100644
--- a/net/batman-adv/originator.h
+++ b/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);
diff --git a/net/batman-adv/routing.c b/net/batman-adv/routing.c
index 1ed9f7c9ecea..a953d5b196a3 100644
--- a/net/batman-adv/routing.c
+++ b/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;
 }
diff --git a/net/batman-adv/send.c b/net/batman-adv/send.c
index 579f5f00a385..843febd1e519 100644
--- a/net/batman-adv/send.c
+++ b/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
diff --git a/net/batman-adv/translation-table.c b/net/batman-adv/translation-table.c
index b6071f675a3e..959dde721c46 100644
--- a/net/batman-adv/translation-table.c
+++ b/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);