The batadv_neigh_node was specific to a batadv_hardif_neigh_node and held an implicit reference to it. But this reference was never stored in form of a pointer in the batadv_neigh_node itself. Instead batadv_neigh_node_release depends on a consistent state of hard_iface->neigh_list and that batadv_hardif_neigh_get always returns the batadv_hardif_neigh_node object which it has a reference for. But batadv_hardif_neigh_get cannot guarantee that because it is working only with rcu_read_lock on this list. It can therefore happen that a neigh_addr is in this list twice or that batadv_hardif_neigh_get cannot find the batadv_hardif_neigh_node for an neigh_addr due to some other list operations taking place at the same time.
Instead add a batadv_hardif_neigh_node pointer directly in batadv_neigh_node which will be used for the reference counter decremented on release of batadv_neigh_node.
Fixes: fed2826b490c ("batman-adv: add list of unique single hop neighbors per hard-interface") Signed-off-by: Sven Eckelmann sven@narfation.org --- See https://www.open-mesh.org/issues/242
v1: - Remove the old code blocks - make the _put unconditional --- net/batman-adv/originator.c | 16 +++++----------- net/batman-adv/types.h | 2 ++ 2 files changed, 7 insertions(+), 11 deletions(-)
diff --git a/net/batman-adv/originator.c b/net/batman-adv/originator.c index 2d288ea..217f8ed 100644 --- a/net/batman-adv/originator.c +++ b/net/batman-adv/originator.c @@ -250,7 +250,6 @@ static void batadv_neigh_node_release(struct kref *ref) { struct hlist_node *node_tmp; struct batadv_neigh_node *neigh_node; - struct batadv_hardif_neigh_node *hardif_neigh; struct batadv_neigh_ifinfo *neigh_ifinfo; struct batadv_algo_ops *bao;
@@ -262,13 +261,7 @@ static void batadv_neigh_node_release(struct kref *ref) batadv_neigh_ifinfo_put(neigh_ifinfo); }
- hardif_neigh = batadv_hardif_neigh_get(neigh_node->if_incoming, - neigh_node->addr); - if (hardif_neigh) { - /* batadv_hardif_neigh_get() increases refcount too */ - batadv_hardif_neigh_put(hardif_neigh); - batadv_hardif_neigh_put(hardif_neigh); - } + batadv_hardif_neigh_put(neigh_node->hardif_neigh);
if (bao->bat_neigh_free) bao->bat_neigh_free(neigh_node); @@ -648,6 +641,10 @@ batadv_neigh_node_new(struct batadv_orig_node *orig_node, neigh_node->if_incoming = hard_iface; neigh_node->orig_node = orig_node;
+ /* increment unique neighbor refcount */ + kref_get(&hardif_neigh->refcount); + neigh_node->hardif_neigh = hardif_neigh; + /* extra reference for return */ kref_init(&neigh_node->refcount); kref_get(&neigh_node->refcount); @@ -656,9 +653,6 @@ batadv_neigh_node_new(struct batadv_orig_node *orig_node, hlist_add_head_rcu(&neigh_node->list, &orig_node->neigh_list); spin_unlock_bh(&orig_node->neigh_list_lock);
- /* increment unique neighbor refcount */ - kref_get(&hardif_neigh->refcount); - batadv_dbg(BATADV_DBG_BATMAN, orig_node->bat_priv, "Creating new neighbor %pM for orig_node %pM on interface %s\n", neigh_addr, orig_node->orig, hard_iface->net_dev->name); diff --git a/net/batman-adv/types.h b/net/batman-adv/types.h index 1480538..58a3fa5 100644 --- a/net/batman-adv/types.h +++ b/net/batman-adv/types.h @@ -433,6 +433,7 @@ struct batadv_hardif_neigh_node { * @ifinfo_lock: lock protecting private ifinfo members and list * @if_incoming: pointer to incoming hard-interface * @last_seen: when last packet via this neighbor was received + * @hardif_neigh: hardif_neigh of this neighbor * @refcount: number of contexts the object is used * @rcu: struct used for freeing in an RCU-safe manner */ @@ -444,6 +445,7 @@ struct batadv_neigh_node { spinlock_t ifinfo_lock; /* protects ifinfo_list and its members */ struct batadv_hard_iface *if_incoming; unsigned long last_seen; + struct batadv_hardif_neigh_node *hardif_neigh; struct kref refcount; struct rcu_head rcu; };