4.9-stable review patch. If anyone has any objections, please let me know.
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From: Sven Eckelmann sven@narfation.org
[ Upstream commit fa122fec8640eb7186ce5a41b83a4c1744ceef8f ]
The function batadv_nc_get_nc_node is responsible for adding new nc_nodes to the in_coding_list and out_coding_list. It first checks whether the entry already is in the list or not. If it is, then the creation of a new entry is aborted.
But the lock for the list is only held when the list is really modified. This could lead to duplicated entries because another context could create an entry with the same key between the check and the list manipulation.
The check and the manipulation of the list must therefore be in the same locked code section.
Fixes: d56b1705e28c ("batman-adv: network coding - detect coding nodes and remove these after timeout") Signed-off-by: Sven Eckelmann sven@narfation.org Acked-by: Marek Lindner mareklindner@neomailbox.ch Signed-off-by: Simon Wunderlich sw@simonwunderlich.de Signed-off-by: Sasha Levin alexander.levin@microsoft.com Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org --- net/batman-adv/network-coding.c | 27 +++++++++++++++------------ 1 file changed, 15 insertions(+), 12 deletions(-)
--- a/net/batman-adv/network-coding.c +++ b/net/batman-adv/network-coding.c @@ -845,16 +845,27 @@ batadv_nc_get_nc_node(struct batadv_priv spinlock_t *lock; /* Used to lock list selected by "int in_coding" */ struct list_head *list;
+ /* Select ingoing or outgoing coding node */ + if (in_coding) { + lock = &orig_neigh_node->in_coding_list_lock; + list = &orig_neigh_node->in_coding_list; + } else { + lock = &orig_neigh_node->out_coding_list_lock; + list = &orig_neigh_node->out_coding_list; + } + + spin_lock_bh(lock); + /* Check if nc_node is already added */ nc_node = batadv_nc_find_nc_node(orig_node, orig_neigh_node, in_coding);
/* Node found */ if (nc_node) - return nc_node; + goto unlock;
nc_node = kzalloc(sizeof(*nc_node), GFP_ATOMIC); if (!nc_node) - return NULL; + goto unlock;
/* Initialize nc_node */ INIT_LIST_HEAD(&nc_node->list); @@ -863,22 +874,14 @@ batadv_nc_get_nc_node(struct batadv_priv kref_get(&orig_neigh_node->refcount); nc_node->orig_node = orig_neigh_node;
- /* Select ingoing or outgoing coding node */ - if (in_coding) { - lock = &orig_neigh_node->in_coding_list_lock; - list = &orig_neigh_node->in_coding_list; - } else { - lock = &orig_neigh_node->out_coding_list_lock; - list = &orig_neigh_node->out_coding_list; - } - batadv_dbg(BATADV_DBG_NC, bat_priv, "Adding nc_node %pM -> %pM\n", nc_node->addr, nc_node->orig_node->orig);
/* Add nc_node to orig_node */ - spin_lock_bh(lock); kref_get(&nc_node->refcount); list_add_tail_rcu(&nc_node->list, list); + +unlock: spin_unlock_bh(lock);
return nc_node;