[B.A.T.M.A.N.] [PATCH 06/28] batman-adv: protect neigh_nodes used outside of rcu_locks with refcounting

Sven Eckelmann
2011-03-05T12:28:20Z

net/batman-adv/routing.c | 40 +++++++++++++++++++++++++++++++---------
1 files changed, 31 insertions(+), 9 deletions(-)

diff --git a/net/batman-adv/routing.c b/net/batman-adv/routing.c
index 97f3216..c15e6c1 100644
--- a/net/batman-adv/routing.c
+++ b/net/batman-adv/routing.c
@@ -151,6 +151,7 @@ static int is_bidirectional_neigh(struct orig_node *orig_node,
struct neigh_node *neigh_node = NULL, *tmp_neigh_node = NULL;
struct hlist_node *node;
unsigned char total_count;
+ int ret = 0;

if (orig_node == orig_neigh_node) {
rcu_read_lock();
@@ -162,7 +163,6 @@ static int is_bidirectional_neigh(struct orig_node *orig_node,
(tmp_neigh_node->if_incoming == if_incoming))
neigh_node = tmp_neigh_node;
}
- rcu_read_unlock();

if (!neigh_node)
neigh_node = create_neighbor(orig_node,
@@ -171,7 +171,10 @@ static int is_bidirectional_neigh(struct orig_node *orig_node,
if_incoming);
/* create_neighbor failed, return 0 */
if (!neigh_node)
- return 0;
+ goto unlock;
+
+ kref_get(&neigh_node->refcount);
+ rcu_read_unlock();

neigh_node->last_valid = jiffies;
} else {
@@ -185,7 +188,6 @@ static int is_bidirectional_neigh(struct orig_node *orig_node,
(tmp_neigh_node->if_incoming == if_incoming))
neigh_node = tmp_neigh_node;
}
- rcu_read_unlock();

if (!neigh_node)
neigh_node = create_neighbor(orig_neigh_node,
@@ -194,7 +196,10 @@ static int is_bidirectional_neigh(struct orig_node *orig_node,
if_incoming);
/* create_neighbor failed, return 0 */
if (!neigh_node)
- return 0;
+ goto unlock;
+
+ kref_get(&neigh_node->refcount);
+ rcu_read_unlock();
}

orig_node->last_valid = jiffies;
@@ -250,9 +255,16 @@ static int is_bidirectional_neigh(struct orig_node *orig_node,
/* if link has the minimum required transmission quality
* consider it bidirectional */
if (batman_packet->tq >= TQ_TOTAL_BIDRECT_LIMIT)
- return 1;
+ ret = 1;

- return 0;
+ goto out;
+
+unlock:
+ rcu_read_unlock();
+out:
+ if (neigh_node)
+ kref_put(&neigh_node->refcount, neigh_node_free_ref);
+ return ret;
}

static void update_orig(struct bat_priv *bat_priv,
@@ -287,23 +299,25 @@ static void update_orig(struct bat_priv *bat_priv,
tmp_neigh_node->tq_avg =
ring_buffer_avg(tmp_neigh_node->tq_recv);
}
- rcu_read_unlock();

if (!neigh_node) {
struct orig_node *orig_tmp;

orig_tmp = get_orig_node(bat_priv, ethhdr->h_source);
if (!orig_tmp)
- return;
+ goto unlock;

neigh_node = create_neighbor(orig_node, orig_tmp,
ethhdr->h_source, if_incoming);
if (!neigh_node)
- return;
+ goto unlock;
} else
bat_dbg(DBG_BATMAN, bat_priv,
"Updating existing last-hop neighbor of originator\n");

+ kref_get(&neigh_node->refcount);
+ rcu_read_unlock();
+
orig_node->flags = batman_packet->flags;
neigh_node->last_valid = jiffies;

@@ -357,6 +371,14 @@ update_gw:
(atomic_read(&bat_priv->gw_mode) == GW_MODE_CLIENT) &&
(atomic_read(&bat_priv->gw_sel_class) > 2))
gw_check_election(bat_priv, orig_node);
+
+ goto out;
+
+unlock:
+ rcu_read_unlock();
+out:
+ if (neigh_node)
+ kref_put(&neigh_node->refcount, neigh_node_free_ref);
}

/* checks whether the host restarted and is in the protection time.
--
1.7.2.3