Return-path: Received: from sacred.ru ([62.205.161.221]:51754 "EHLO sacred.ru" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751315AbYDWIbV (ORCPT ); Wed, 23 Apr 2008 04:31:21 -0400 Message-ID: <480EE983.4020209@openvz.org> (sfid-20080423_103205_681166_E7D0FFCA) Date: Wed, 23 Apr 2008 11:47:15 +0400 From: Pavel Emelyanov MIME-Version: 1.0 To: Johannes Berg , "John W. Linville" CC: Linux Netdev List , linux-wireless@vger.kernel.org Subject: [PATCH] mac80211: Fix race between ieee80211_rx_bss_put and lookup routines. Content-Type: text/plain; charset=ISO-8859-1 Sender: linux-wireless-owner@vger.kernel.org List-ID: 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 --- 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);