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@xxxxxxxxxx>
---
diff --git a/net/mac80211/mlme.c b/net/mac80211/mlme.c
index 6b75cb6..dac3c2a 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);
--
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