rt2x00: Fix for race condition while update beacon

The patch "Implement set_tim callback for all drivers" can cause kernel
oops in rt73usb_write_beacon. The oops is caused by one of the following
race conditions:
* In case of two near calls to set_tim: rt2x00lib_beacondone_iter is
cleaning the beacon skb, whereas rt73usb_write_beacon is still using it.
* In case of two near updates of beacon: first as the result of set_tim
and second as the result of a call from an application (e.g. hostapd).
This patch fixes the race condition by rearranging the update logic and
guarding rt2x00_intf->beacon->skb with a mutex.

Signed-off-by: Igor Perminov <igor.perminov@inbox.ru>
Signed-off-by: Ivo van Doorn <IvDoorn@gmail.com>
Signed-off-by: John W. Linville <linville@tuxdriver.com>

diff --git a/drivers/net/wireless/rt2x00/rt2x00.h b/drivers/net/wireless/rt2x00/rt2x00.h
index e6e73be..7c74c4e 100644 (file)
--- a/drivers/net/wireless/rt2x00/rt2x00.h
+++ b/drivers/net/wireless/rt2x00/rt2x00.h
@@ -333,6 +333,11 @@ struct rt2x00_intf {
         */
        u8 bssid[ETH_ALEN];
 
         */
        u8 bssid[ETH_ALEN];
 

+       /*
+        * beacon->skb must be protected with the mutex.
+        */
+       struct mutex beacon_skb_mutex;
+

        /*
         * Entry in the beacon queue which belongs to
         * this interface. Each interface has its own
        /*
         * Entry in the beacon queue which belongs to
         * this interface. Each interface has its own

diff --git a/drivers/net/wireless/rt2x00/rt2x00dev.c b/drivers/net/wireless/rt2x00/rt2x00dev.c
index e0348cc..b6676c6 100644 (file)
--- a/drivers/net/wireless/rt2x00/rt2x00dev.c
+++ b/drivers/net/wireless/rt2x00/rt2x00dev.c
@@ -186,7 +186,6 @@ static void rt2x00lib_intf_scheduled(struct work_struct *work)
 static void rt2x00lib_beacondone_iter(void *data, u8 *mac,
                                      struct ieee80211_vif *vif)
 {
 static void rt2x00lib_beacondone_iter(void *data, u8 *mac,
                                      struct ieee80211_vif *vif)
 {

-       struct rt2x00_dev *rt2x00dev = data;

        struct rt2x00_intf *intf = vif_to_intf(vif);
 
        if (vif->type != NL80211_IFTYPE_AP &&
        struct rt2x00_intf *intf = vif_to_intf(vif);
 
        if (vif->type != NL80211_IFTYPE_AP &&


@@ -195,12 +194,6 @@ static void rt2x00lib_beacondone_iter(void *data, u8 *mac,
            vif->type != NL80211_IFTYPE_WDS)
                return;
 
            vif->type != NL80211_IFTYPE_WDS)
                return;
 

-       /*
-        * Clean up the beacon skb.
-        */
-       rt2x00queue_free_skb(rt2x00dev, intf->beacon->skb);
-       intf->beacon->skb = NULL;
-

        spin_lock(&intf->lock);
        intf->delayed_flags |= DELAYED_UPDATE_BEACON;
        spin_unlock(&intf->lock);
        spin_lock(&intf->lock);
        intf->delayed_flags |= DELAYED_UPDATE_BEACON;
        spin_unlock(&intf->lock);

diff --git a/drivers/net/wireless/rt2x00/rt2x00mac.c b/drivers/net/wireless/rt2x00/rt2x00mac.c
index 4164fce..74451f9 100644 (file)
--- a/drivers/net/wireless/rt2x00/rt2x00mac.c
+++ b/drivers/net/wireless/rt2x00/rt2x00mac.c
@@ -274,6 +274,7 @@ int rt2x00mac_add_interface(struct ieee80211_hw *hw,
 
        spin_lock_init(&intf->lock);
        spin_lock_init(&intf->seqlock);
 
        spin_lock_init(&intf->lock);
        spin_lock_init(&intf->seqlock);

+       mutex_init(&intf->beacon_skb_mutex);

        intf->beacon = entry;
 
        if (conf->type == NL80211_IFTYPE_AP)
        intf->beacon = entry;
 
        if (conf->type == NL80211_IFTYPE_AP)

diff --git a/drivers/net/wireless/rt2x00/rt2x00queue.c b/drivers/net/wireless/rt2x00/rt2x00queue.c
index e67e339..06af823 100644 (file)
--- a/drivers/net/wireless/rt2x00/rt2x00queue.c
+++ b/drivers/net/wireless/rt2x00/rt2x00queue.c
@@ -503,14 +503,25 @@ int rt2x00queue_update_beacon(struct rt2x00_dev *rt2x00dev,
        if (unlikely(!intf->beacon))
                return -ENOBUFS;
 
        if (unlikely(!intf->beacon))
                return -ENOBUFS;
 

+       mutex_lock(&intf->beacon_skb_mutex);
+
+       /*
+        * Clean up the beacon skb.
+        */
+       rt2x00queue_free_skb(rt2x00dev, intf->beacon->skb);
+       intf->beacon->skb = NULL;
+

        if (!enable_beacon) {
                rt2x00dev->ops->lib->kill_tx_queue(rt2x00dev, QID_BEACON);
        if (!enable_beacon) {
                rt2x00dev->ops->lib->kill_tx_queue(rt2x00dev, QID_BEACON);

+               mutex_unlock(&intf->beacon_skb_mutex);

                return 0;
        }
 
        intf->beacon->skb = ieee80211_beacon_get(rt2x00dev->hw, vif);
                return 0;
        }
 
        intf->beacon->skb = ieee80211_beacon_get(rt2x00dev->hw, vif);

-       if (!intf->beacon->skb)
+       if (!intf->beacon->skb) {
+               mutex_unlock(&intf->beacon_skb_mutex);

                return -ENOMEM;
                return -ENOMEM;

+       }

 
        /*
         * Copy all TX descriptor information into txdesc,
 
        /*
         * Copy all TX descriptor information into txdesc,


@@ -548,6 +559,8 @@ int rt2x00queue_update_beacon(struct rt2x00_dev *rt2x00dev,
        rt2x00dev->ops->lib->write_beacon(intf->beacon);
        rt2x00dev->ops->lib->kick_tx_queue(rt2x00dev, QID_BEACON);
 
        rt2x00dev->ops->lib->write_beacon(intf->beacon);
        rt2x00dev->ops->lib->kick_tx_queue(rt2x00dev, QID_BEACON);
 

+       mutex_unlock(&intf->beacon_skb_mutex);
+

        return 0;
 }
 
        return 0;
 }