3.16.62-rc1 review patch. If anyone has any objections, please let me know.
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From: Sven Eckelmann sven@narfation.org
commit ae3cdc97dc10c7a3b31f297dab429bfb774c9ccb upstream.
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: ef26157747d4 ("batman-adv: tvlv - basic infrastructure") Signed-off-by: Sven Eckelmann sven@narfation.org Signed-off-by: Simon Wunderlich sw@simonwunderlich.de [bwh: Backported to 3.16: adjust filename, context] Signed-off-by: Ben Hutchings ben@decadent.org.uk --- net/batman-adv/main.c | 8 ++++++-- 1 file changed, 6 insertions(+), 2 deletions(-)
--- a/net/batman-adv/main.c +++ b/net/batman-adv/main.c @@ -1058,15 +1058,20 @@ void batadv_tvlv_handler_register(struct { 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_free_ref(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; @@ -1076,7 +1081,6 @@ void batadv_tvlv_handler_register(struct atomic_set(&tvlv_handler->refcount, 1); INIT_HLIST_NODE(&tvlv_handler->list);
- spin_lock_bh(&bat_priv->tvlv.handler_list_lock); hlist_add_head_rcu(&tvlv_handler->list, &bat_priv->tvlv.handler_list); spin_unlock_bh(&bat_priv->tvlv.handler_list_lock); }