4.9-stable review patch. If anyone has any objections, please let me know.
------------------
From: Sven Eckelmann sven@narfation.org
[ Upstream commit e7136e48ffdfb9f37b0820f619380485eb407361 ]
The function batadv_tt_global_orig_entry_add is responsible for adding new tt_orig_list_entry to the orig_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: d657e621a0f5 ("batman-adv: add reference counting for type batadv_tt_orig_list_entry") Signed-off-by: Sven Eckelmann sven@narfation.org 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/translation-table.c | 6 ++++-- 1 file changed, 4 insertions(+), 2 deletions(-)
--- a/net/batman-adv/translation-table.c +++ b/net/batman-adv/translation-table.c @@ -1550,6 +1550,8 @@ batadv_tt_global_orig_entry_add(struct b { struct batadv_tt_orig_list_entry *orig_entry;
+ spin_lock_bh(&tt_global->list_lock); + orig_entry = batadv_tt_global_orig_entry_find(tt_global, orig_node); if (orig_entry) { /* refresh the ttvn: the current value could be a bogus one that @@ -1570,16 +1572,16 @@ batadv_tt_global_orig_entry_add(struct b orig_entry->ttvn = ttvn; kref_init(&orig_entry->refcount);
- spin_lock_bh(&tt_global->list_lock); kref_get(&orig_entry->refcount); hlist_add_head_rcu(&orig_entry->list, &tt_global->orig_list); - spin_unlock_bh(&tt_global->list_lock); atomic_inc(&tt_global->orig_list_count);
out: if (orig_entry) batadv_tt_orig_list_entry_put(orig_entry); + + spin_unlock_bh(&tt_global->list_lock); }
/**