diff options
| author | Patrick McHardy <kaber@trash.net> | 2007-03-22 12:25:20 -0700 |
|---|---|---|
| committer | David S. Miller <davem@davemloft.net> | 2007-03-22 12:25:20 -0700 |
| commit | b19cbe2a1695c09c74f83646c4b82b51123b3690 (patch) | |
| tree | 138761d3360b981292569e318757e53502f8887b | |
| parent | ec25615b9ddd5c584b4066652840581fdb6c5e7a (diff) | |
[BRIDGE]: Fix fdb RCU race
br_fdb_get use atomic_inc to increase the refcount of an element found
on a RCU protected list, which can lead to the following race:
CPU0 CPU1
br_fdb_get: rcu_read_lock
__br_fdb_get: find element
fdb_delete: hlist_del_rcu
br_fdb_put
br_fdb_put: atomic_dec_and_test
call_rcu(fdb_rcu_free) br_fdb_get: atomic_inc
rcu_read_unlock
fdb_rcu_free: kmem_cache_free
Use atomic_inc_not_zero instead.
Signed-off-by: Patrick McHardy <kaber@trash.net>
Signed-off-by: David S. Miller <davem@davemloft.net>
| -rw-r--r-- | net/bridge/br_fdb.c | 4 |
1 files changed, 2 insertions, 2 deletions
diff --git a/net/bridge/br_fdb.c b/net/bridge/br_fdb.c index def2e403f93..8d566c13cc7 100644 --- a/net/bridge/br_fdb.c +++ b/net/bridge/br_fdb.c @@ -197,8 +197,8 @@ struct net_bridge_fdb_entry *br_fdb_get(struct net_bridge *br, rcu_read_lock(); fdb = __br_fdb_get(br, addr); - if (fdb) - atomic_inc(&fdb->use_count); + if (fdb && !atomic_inc_not_zero(&fdb->use_count)) + fdb = NULL; rcu_read_unlock(); return fdb; } |