From 1ebebea8e844d01c80b93b8ee4d696ee7c0cbc27 Mon Sep 17 00:00:00 2001 From: Pavel Emelyanov Date: Wed, 23 Apr 2008 11:47:15 +0400 Subject: [PATCH] mac80211: Fix race between ieee80211_rx_bss_put and lookup routines. The put routine first decrements the users counter and then (if it is zero) locks the sta_bss_lock and removes one from the list and the hash. Thus, any of ieee80211_sta_config_auth, ieee80211_rx_bss_get or ieee80211_rx_mesh_bss_get can race with it by finding a bss that is about to get kfree-ed. Using atomic_dec_and_lock in ieee80211_rx_bss_put takes care of this race. Signed-off-by: Pavel Emelyanov Signed-off-by: John W. Linville --- net/mac80211/mlme.c | 7 +++++-- 1 file changed, 5 insertions(+), 2 deletions(-) diff --git a/net/mac80211/mlme.c b/net/mac80211/mlme.c index c0a5345c8a61..a5e5c31c23ab 100644 --- a/net/mac80211/mlme.c +++ b/net/mac80211/mlme.c @@ -2248,10 +2248,13 @@ static void ieee80211_rx_bss_put(struct net_device *dev, struct ieee80211_sta_bss *bss) { struct ieee80211_local *local = wdev_priv(dev->ieee80211_ptr); - if (!atomic_dec_and_test(&bss->users)) + + local_bh_disable(); + if (!atomic_dec_and_lock(&bss->users, &local->sta_bss_lock)) { + local_bh_enable(); return; + } - spin_lock_bh(&local->sta_bss_lock); __ieee80211_rx_bss_hash_del(dev, bss); list_del(&bss->list); spin_unlock_bh(&local->sta_bss_lock); -- 2.20.1