batman-adv: Correct rcu refcounting for neigh_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/types.h b/net/batman-adv/types.h
index 1f833f0..084604a 100644
--- a/net/batman-adv/types.h
+++ b/net/batman-adv/types.h
@@ -117,9 +117,8 @@
struct list_head bonding_list;
unsigned long last_valid;
unsigned long real_bits[NUM_WORDS];
- struct kref refcount;
+ atomic_t refcount;
struct rcu_head rcu;
- struct rcu_head rcu_bond;
struct orig_node *orig_node;
struct batman_if *if_incoming;
};