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batman-adv: Fix list removal of batadv_hardif_neigh_node

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The neigh_list with batadv_hardif_neigh_node objects is accessed with only
rcu_read_lock in batadv_hardif_neigh_get and batadv_iv_neigh_print. Thus it
is not allowed to kfree the object before the rcu grace period ends (which
may still protects context accessing this object). Therefore the object has
first to be removed from the neigh_list and then it has either wait with
synchronize_rcu or call_rcu till the grace period ends before it can be
freed.

Fixes: cef63419f7 ("batman-adv: add list of unique single hop neighbors per hard-interface")
Signed-off-by: Sven Eckelmann <sven@narfation.org>
Signed-off-by: Marek Lindner <mareklindner@neomailbox.ch>
Signed-off-by: Antonio Quartulli <a@unstable.cc>
This commit is contained in:
Sven Eckelmann 2016-01-05 12:06:17 +01:00 committed by Antonio Quartulli
parent af63cf51b7
commit bab7c6c3de
1 changed files with 12 additions and 6 deletions
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18
net/batman-adv/originator.c
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@ -211,10 +211,6 @@ static void batadv_hardif_neigh_free_rcu(struct rcu_head *rcu)
hardif_neigh = container_of(rcu, struct batadv_hardif_neigh_node, rcu);
spin_lock_bh(&hardif_neigh->if_incoming->neigh_list_lock);
hlist_del_init_rcu(&hardif_neigh->list);
spin_unlock_bh(&hardif_neigh->if_incoming->neigh_list_lock);
batadv_hardif_free_ref_now(hardif_neigh->if_incoming);
kfree(hardif_neigh);
}
@ -227,8 +223,13 @@ static void batadv_hardif_neigh_free_rcu(struct rcu_head *rcu)
static void
batadv_hardif_neigh_free_now(struct batadv_hardif_neigh_node *hardif_neigh)
{
if (atomic_dec_and_test(&hardif_neigh->refcount))
if (atomic_dec_and_test(&hardif_neigh->refcount)) {
spin_lock_bh(&hardif_neigh->if_incoming->neigh_list_lock);
hlist_del_init_rcu(&hardif_neigh->list);
spin_unlock_bh(&hardif_neigh->if_incoming->neigh_list_lock);
batadv_hardif_neigh_free_rcu(&hardif_neigh->rcu);
}
}
/**
@ -238,8 +239,13 @@ batadv_hardif_neigh_free_now(struct batadv_hardif_neigh_node *hardif_neigh)
*/
void batadv_hardif_neigh_free_ref(struct batadv_hardif_neigh_node *hardif_neigh)
{
if (atomic_dec_and_test(&hardif_neigh->refcount))
if (atomic_dec_and_test(&hardif_neigh->refcount)) {
spin_lock_bh(&hardif_neigh->if_incoming->neigh_list_lock);
hlist_del_init_rcu(&hardif_neigh->list);
spin_unlock_bh(&hardif_neigh->if_incoming->neigh_list_lock);
call_rcu(&hardif_neigh->rcu, batadv_hardif_neigh_free_rcu);
}
}
/**