From 365a0ea769fb125d2823a6360e8e41a861ce664b Mon Sep 17 00:00:00 2001 From: Sven Eckelmann Date: Sun, 12 Aug 2018 21:04:44 +0200 Subject: batman-adv: Prevent duplicated global TT entry commit e7136e48ffdfb9f37b0820f619380485eb407361 upstream. 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 Signed-off-by: Simon Wunderlich [bwh: Backported to 3.16: adjust context] Signed-off-by: Ben Hutchings --- net/batman-adv/translation-table.c | 6 ++++-- 1 file changed, 4 insertions(+), 2 deletions(-) (limited to 'net/batman-adv') diff --git a/net/batman-adv/translation-table.c b/net/batman-adv/translation-table.c index ce0678140a32..c9ac7d948a21 100644 --- a/net/batman-adv/translation-table.c +++ b/net/batman-adv/translation-table.c @@ -1287,6 +1287,8 @@ batadv_tt_global_orig_entry_add(struct batadv_tt_global_entry *tt_global, { 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 @@ -1309,10 +1311,8 @@ batadv_tt_global_orig_entry_add(struct batadv_tt_global_entry *tt_global, orig_entry->flags = flags; atomic_set(&orig_entry->refcount, 2); - spin_lock_bh(&tt_global->list_lock); 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); sync_flags: @@ -1320,6 +1320,8 @@ sync_flags: out: if (orig_entry) batadv_tt_orig_list_entry_free_ref(orig_entry); + + spin_unlock_bh(&tt_global->list_lock); } /** -- cgit v1.2.3