batman-adv: Correct rcu refcounting for orig_node

It might be possible that 2 threads access the same data in the same
rcu grace period. The first thread calls call_rcu() to decrement the
refcount and free the data while the second thread increases the
refcount to use the data. To avoid this race condition all refcount
operations have to be atomic.

Reported-by: Sven Eckelmann <sven@narfation.org>
Signed-off-by: Marek Lindner <lindner_marek@yahoo.de>

diff --git a/net/batman-adv/gateway_client.c b/net/batman-adv/gateway_client.c
index 41eba8a660f58583c3790dd8090983eb7c253abb..3cc43558cf9cbb0958d55f4f6ed236f9c3873322 100644 (file)
--- a/net/batman-adv/gateway_client.c
+++ b/net/batman-adv/gateway_client.c
@@ -53,9 +53,11 @@ void *gw_get_selected(struct bat_priv *bat_priv)
                goto out;
 
        orig_node = curr_gateway_tmp->orig_node;
+       if (!orig_node)
+               goto out;
 
-       if (orig_node)
-               kref_get(&orig_node->refcount);
+       if (!atomic_inc_not_zero(&orig_node->refcount))
+               orig_node = NULL;
 
 out:
        rcu_read_unlock();

diff --git a/net/batman-adv/icmp_socket.c b/net/batman-adv/icmp_socket.c
index 139b7336adf9bbcd794a2100531cc3bac2feae33..a0a35b1af1677cd2952e831cfba66256de76e405 100644 (file)
--- a/net/batman-adv/icmp_socket.c
+++ b/net/batman-adv/icmp_socket.c
@@ -271,7 +271,7 @@ out:
        if (neigh_node)
                neigh_node_free_ref(neigh_node);
        if (orig_node)
-               kref_put(&orig_node->refcount, orig_node_free_ref);
+               orig_node_free_ref(orig_node);
        return len;
 }
 

diff --git a/net/batman-adv/originator.c b/net/batman-adv/originator.c
index bdcb399329dd3eaba2a03e4617d0291cf985a8d1..a70debebfc5b3eb20f27f92a2cef9ea173f201df 100644 (file)
--- a/net/batman-adv/originator.c
+++ b/net/batman-adv/originator.c
@@ -102,13 +102,13 @@ struct neigh_node *create_neighbor(struct orig_node *orig_node,
        return neigh_node;
 }
 
-void orig_node_free_ref(struct kref *refcount)
+static void orig_node_free_rcu(struct rcu_head *rcu)
 {
        struct hlist_node *node, *node_tmp;
        struct neigh_node *neigh_node, *tmp_neigh_node;
        struct orig_node *orig_node;
 
-       orig_node = container_of(refcount, struct orig_node, refcount);
+       orig_node = container_of(rcu, struct orig_node, rcu);
 
        spin_lock_bh(&orig_node->neigh_list_lock);
 
@@ -137,6 +137,12 @@ void orig_node_free_ref(struct kref *refcount)
        kfree(orig_node);
 }
 
+void orig_node_free_ref(struct orig_node *orig_node)
+{
+       if (atomic_dec_and_test(&orig_node->refcount))
+               call_rcu(&orig_node->rcu, orig_node_free_rcu);
+}
+
 void originator_free(struct bat_priv *bat_priv)
 {
        struct hashtable_t *hash = bat_priv->orig_hash;
@@ -163,7 +169,7 @@ void originator_free(struct bat_priv *bat_priv)
                                          head, hash_entry) {
 
                        hlist_del_rcu(node);
-                       kref_put(&orig_node->refcount, orig_node_free_ref);
+                       orig_node_free_ref(orig_node);
                }
                spin_unlock_bh(list_lock);
        }
@@ -196,7 +202,9 @@ struct orig_node *get_orig_node(struct bat_priv *bat_priv, uint8_t *addr)
        spin_lock_init(&orig_node->ogm_cnt_lock);
        spin_lock_init(&orig_node->bcast_seqno_lock);
        spin_lock_init(&orig_node->neigh_list_lock);
-       kref_init(&orig_node->refcount);
+
+       /* extra reference for return */
+       atomic_set(&orig_node->refcount, 2);
 
        orig_node->bat_priv = bat_priv;
        memcpy(orig_node->orig, addr, ETH_ALEN);
@@ -229,8 +237,6 @@ struct orig_node *get_orig_node(struct bat_priv *bat_priv, uint8_t *addr)
        if (hash_added < 0)
                goto free_bcast_own_sum;
 
-       /* extra reference for return */
-       kref_get(&orig_node->refcount);
        return orig_node;
 free_bcast_own_sum:
        kfree(orig_node->bcast_own_sum);
@@ -348,8 +354,7 @@ static void _purge_orig(struct bat_priv *bat_priv)
                                if (orig_node->gw_flags)
                                        gw_node_delete(bat_priv, orig_node);
                                hlist_del_rcu(node);
-                               kref_put(&orig_node->refcount,
-                                        orig_node_free_ref);
+                               orig_node_free_ref(orig_node);
                                continue;
                        }
 

diff --git a/net/batman-adv/originator.h b/net/batman-adv/originator.h
index b4b9a09259fd5cde0d10ba700b5eb6cd08196a02..3d7a39d4df0f946a8e3cccdcab748b3084216c29 100644 (file)
--- a/net/batman-adv/originator.h
+++ b/net/batman-adv/originator.h
@@ -27,7 +27,7 @@
 int originator_init(struct bat_priv *bat_priv);
 void originator_free(struct bat_priv *bat_priv);
 void purge_orig_ref(struct bat_priv *bat_priv);
-void orig_node_free_ref(struct kref *refcount);
+void orig_node_free_ref(struct orig_node *orig_node);
 struct orig_node *get_orig_node(struct bat_priv *bat_priv, uint8_t *addr);
 struct neigh_node *create_neighbor(struct orig_node *orig_node,
                                   struct orig_node *orig_neigh_node,
@@ -88,8 +88,10 @@ static inline struct orig_node *orig_hash_find(struct bat_priv *bat_priv,
                if (!compare_eth(orig_node, data))
                        continue;
 
+               if (!atomic_inc_not_zero(&orig_node->refcount))
+                       continue;
+
                orig_node_tmp = orig_node;
-               kref_get(&orig_node_tmp->refcount);
                break;
        }
        rcu_read_unlock();

diff --git a/net/batman-adv/routing.c b/net/batman-adv/routing.c
index fc4c12a049da7c117cec3cee91e489d090fea010..9863c03a21373ff001b441df05ae1301dcaf99fb 100644 (file)
--- a/net/batman-adv/routing.c
+++ b/net/batman-adv/routing.c
@@ -420,7 +420,7 @@ static void update_orig(struct bat_priv *bat_priv,
                neigh_node = create_neighbor(orig_node, orig_tmp,
                                             ethhdr->h_source, if_incoming);
 
-               kref_put(&orig_tmp->refcount, orig_node_free_ref);
+               orig_node_free_ref(orig_tmp);
                if (!neigh_node)
                        goto unlock;
 
@@ -604,7 +604,7 @@ static char count_real_packets(struct ethhdr *ethhdr,
 
 out:
        spin_unlock_bh(&orig_node->ogm_cnt_lock);
-       kref_put(&orig_node->refcount, orig_node_free_ref);
+       orig_node_free_ref(orig_node);
        return ret;
 }
 
@@ -730,7 +730,7 @@ void receive_bat_packet(struct ethhdr *ethhdr,
 
                bat_dbg(DBG_BATMAN, bat_priv, "Drop packet: "
                        "originator packet from myself (via neighbor)\n");
-               kref_put(&orig_neigh_node->refcount, orig_node_free_ref);
+               orig_node_free_ref(orig_neigh_node);
                return;
        }
 
@@ -835,10 +835,10 @@ void receive_bat_packet(struct ethhdr *ethhdr,
                                0, hna_buff_len, if_incoming);
 
 out_neigh:
-       if (!is_single_hop_neigh)
-               kref_put(&orig_neigh_node->refcount, orig_node_free_ref);
+       if ((orig_neigh_node) && (!is_single_hop_neigh))
+               orig_node_free_ref(orig_neigh_node);
 out:
-       kref_put(&orig_node->refcount, orig_node_free_ref);
+       orig_node_free_ref(orig_node);
 }
 
 int recv_bat_packet(struct sk_buff *skb, struct batman_if *batman_if)
@@ -952,7 +952,7 @@ out:
        if (neigh_node)
                neigh_node_free_ref(neigh_node);
        if (orig_node)
-               kref_put(&orig_node->refcount, orig_node_free_ref);
+               orig_node_free_ref(orig_node);
        return ret;
 }
 
@@ -1028,7 +1028,7 @@ out:
        if (neigh_node)
                neigh_node_free_ref(neigh_node);
        if (orig_node)
-               kref_put(&orig_node->refcount, orig_node_free_ref);
+               orig_node_free_ref(orig_node);
        return ret;
 }
 
@@ -1134,7 +1134,7 @@ out:
        if (neigh_node)
                neigh_node_free_ref(neigh_node);
        if (orig_node)
-               kref_put(&orig_node->refcount, orig_node_free_ref);
+               orig_node_free_ref(orig_node);
        return ret;
 }
 
@@ -1189,7 +1189,7 @@ struct neigh_node *find_router(struct bat_priv *bat_priv,
                if (!primary_orig_node)
                        goto return_router;
 
-               kref_put(&primary_orig_node->refcount, orig_node_free_ref);
+               orig_node_free_ref(primary_orig_node);
        }
 
        /* with less than 2 candidates, we can't do any
@@ -1401,7 +1401,7 @@ out:
        if (neigh_node)
                neigh_node_free_ref(neigh_node);
        if (orig_node)
-               kref_put(&orig_node->refcount, orig_node_free_ref);
+               orig_node_free_ref(orig_node);
        return ret;
 }
 
@@ -1543,7 +1543,7 @@ spin_unlock:
        spin_unlock_bh(&bat_priv->orig_hash_lock);
 out:
        if (orig_node)
-               kref_put(&orig_node->refcount, orig_node_free_ref);
+               orig_node_free_ref(orig_node);
        return ret;
 }
 

diff --git a/net/batman-adv/translation-table.c b/net/batman-adv/translation-table.c
index cd8a58396d26b025014f85db919040bc5d34d08c..8d15b48d1692455c7a71c34c8d1031fc426bca14 100644 (file)
--- a/net/batman-adv/translation-table.c
+++ b/net/batman-adv/translation-table.c
@@ -589,17 +589,20 @@ void hna_global_free(struct bat_priv *bat_priv)
 struct orig_node *transtable_search(struct bat_priv *bat_priv, uint8_t *addr)
 {
        struct hna_global_entry *hna_global_entry;
+       struct orig_node *orig_node = NULL;
 
        spin_lock_bh(&bat_priv->hna_ghash_lock);
        hna_global_entry = hna_global_hash_find(bat_priv, addr);
 
-       if (hna_global_entry)
-               kref_get(&hna_global_entry->orig_node->refcount);
+       if (!hna_global_entry)
+               goto out;
 
-       spin_unlock_bh(&bat_priv->hna_ghash_lock);
+       if (!atomic_inc_not_zero(&hna_global_entry->orig_node->refcount))
+               goto out;
 
-       if (!hna_global_entry)
-               return NULL;
+       orig_node = hna_global_entry->orig_node;
 
-       return hna_global_entry->orig_node;
+out:
+       spin_unlock_bh(&bat_priv->hna_ghash_lock);
+       return orig_node;
 }

diff --git a/net/batman-adv/types.h b/net/batman-adv/types.h
index 40365b81bc4052f49a670990695a890fe3e30424..1be76feddee1da7fd639298c927789631b9c9f6f 100644 (file)
--- a/net/batman-adv/types.h
+++ b/net/batman-adv/types.h
@@ -84,7 +84,8 @@ struct orig_node {
        struct hlist_head neigh_list;
        struct list_head frag_list;
        spinlock_t neigh_list_lock; /* protects neighbor list */
-       struct kref refcount;
+       atomic_t refcount;
+       struct rcu_head rcu;
        struct hlist_node hash_entry;
        struct bat_priv *bat_priv;
        unsigned long last_frag_packet;

diff --git a/net/batman-adv/unicast.c b/net/batman-adv/unicast.c
index 2d5daac5203475d35e71abfa26c231150778749b..2ab819841231fddba2cd96aa9ad8932653783bd4 100644 (file)
--- a/net/batman-adv/unicast.c
+++ b/net/batman-adv/unicast.c
@@ -211,7 +211,7 @@ unlock:
        spin_unlock_bh(&bat_priv->orig_hash_lock);
 out:
        if (orig_node)
-               kref_put(&orig_node->refcount, orig_node_free_ref);
+               orig_node_free_ref(orig_node);
        return ret;
 }
 
@@ -280,7 +280,7 @@ int unicast_send_skb(struct sk_buff *skb, struct bat_priv *bat_priv)
 {
        struct ethhdr *ethhdr = (struct ethhdr *)skb->data;
        struct unicast_packet *unicast_packet;
-       struct orig_node *orig_node = NULL;
+       struct orig_node *orig_node;
        struct batman_if *batman_if;
        struct neigh_node *neigh_node;
        int data_len = skb->len;
@@ -347,7 +347,7 @@ out:
        if (neigh_node)
                neigh_node_free_ref(neigh_node);
        if (orig_node)
-               kref_put(&orig_node->refcount, orig_node_free_ref);
+               orig_node_free_ref(orig_node);
        if (ret == 1)
                kfree_skb(skb);
        return ret;

diff --git a/net/batman-adv/vis.c b/net/batman-adv/vis.c
index d179acabb04cd8808c3a4119a5d62134dd178fea..89722425dcb20337d8324404e7de2c6399d93ccd 100644 (file)
--- a/net/batman-adv/vis.c
+++ b/net/batman-adv/vis.c
@@ -826,7 +826,7 @@ out:
        if (neigh_node)
                neigh_node_free_ref(neigh_node);
        if (orig_node)
-               kref_put(&orig_node->refcount, orig_node_free_ref);
+               orig_node_free_ref(orig_node);
        return;
 }