Repository : ssh://git@open-mesh.org/batman-adv
On branch : maint
commit acabad79e01740525cf4ff8ce6e9a210b683d420 Author: Sven Eckelmann sven@narfation.org Date: Thu Sep 6 14:35:28 2018 +0200
batman-adv: Prevent duplicated tvlv handler
The function batadv_tvlv_handler_register is responsible for adding new tvlv_handler to the handler_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: 0b6aa0d43767 ("batman-adv: tvlv - basic infrastructure") Signed-off-by: Sven Eckelmann sven@narfation.org Acked-by: Marek Lindner mareklindner@neomailbox.ch
acabad79e01740525cf4ff8ce6e9a210b683d420 net/batman-adv/tvlv.c | 8 ++++++-- 1 file changed, 6 insertions(+), 2 deletions(-)
diff --git a/net/batman-adv/tvlv.c b/net/batman-adv/tvlv.c index a637458..40e69c9 100644 --- a/net/batman-adv/tvlv.c +++ b/net/batman-adv/tvlv.c @@ -529,15 +529,20 @@ void batadv_tvlv_handler_register(struct batadv_priv *bat_priv, { struct batadv_tvlv_handler *tvlv_handler;
+ spin_lock_bh(&bat_priv->tvlv.handler_list_lock); + tvlv_handler = batadv_tvlv_handler_get(bat_priv, type, version); if (tvlv_handler) { + spin_unlock_bh(&bat_priv->tvlv.handler_list_lock); batadv_tvlv_handler_put(tvlv_handler); return; }
tvlv_handler = kzalloc(sizeof(*tvlv_handler), GFP_ATOMIC); - if (!tvlv_handler) + if (!tvlv_handler) { + spin_unlock_bh(&bat_priv->tvlv.handler_list_lock); return; + }
tvlv_handler->ogm_handler = optr; tvlv_handler->unicast_handler = uptr; @@ -547,7 +552,6 @@ void batadv_tvlv_handler_register(struct batadv_priv *bat_priv, kref_init(&tvlv_handler->refcount); INIT_HLIST_NODE(&tvlv_handler->list);
- spin_lock_bh(&bat_priv->tvlv.handler_list_lock); kref_get(&tvlv_handler->refcount); hlist_add_head_rcu(&tvlv_handler->list, &bat_priv->tvlv.handler_list); spin_unlock_bh(&bat_priv->tvlv.handler_list_lock);