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mac80211: Fix race between ieee80211_rx_bss_put and lookup routines.

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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 <xemul@openvz.org>
Signed-off-by: John W. Linville <linville@tuxdriver.com>
This commit is contained in:
Pavel Emelyanov 2008-04-23 11:47:15 +04:00 committed by John W. Linville
parent d1d8f44a4e
commit 1ebebea8e8
1 changed files with 6 additions and 3 deletions
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9
net/mac80211/mlme.c
View file

@ -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))
return;
spin_lock_bh(&local->sta_bss_lock);
local_bh_disable();
if (!atomic_dec_and_lock(&bss->users, &local->sta_bss_lock)) {
local_bh_enable();
return;
}
__ieee80211_rx_bss_hash_del(dev, bss);
list_del(&bss->list);
spin_unlock_bh(&local->sta_bss_lock);