From: Igor Perminov <igor.perminov@xxxxxxxx>
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@xxxxxxxx>
Signed-off-by: Ivo van Doorn <IvDoorn@xxxxxxxxx>
---
drivers/net/wireless/rt2x00/rt2x00.h | 5 +++++
drivers/net/wireless/rt2x00/rt2x00dev.c | 7 -------
drivers/net/wireless/rt2x00/rt2x00mac.c | 1 +
drivers/net/wireless/rt2x00/rt2x00queue.c | 15 ++++++++++++++-
4 files changed, 20 insertions(+), 8 deletions(-)
diff --git a/drivers/net/wireless/rt2x00/rt2x00.h b/drivers/net/wireless/rt2x00/rt2x00.h
index 19ca146..806ef60 100644
--- a/drivers/net/wireless/rt2x00/rt2x00.h
+++ b/drivers/net/wireless/rt2x00/rt2x00.h
@@ -334,6 +334,11 @@ struct rt2x00_intf {
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
* dedicated beacon entry.
diff --git a/drivers/net/wireless/rt2x00/rt2x00dev.c b/drivers/net/wireless/rt2x00/rt2x00dev.c
index e0348cc..b6676c6 100644
--- 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)
{
- struct rt2x00_dev *rt2x00dev = data;
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;
- /*
- * 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);
diff --git a/drivers/net/wireless/rt2x00/rt2x00mac.c b/drivers/net/wireless/rt2x00/rt2x00mac.c
index 4164fce..74451f9 100644
--- 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);
+ mutex_init(&intf->beacon_skb_mutex);
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
--- 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;
+ 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);
+ mutex_unlock(&intf->beacon_skb_mutex);
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;
+ }
/*
* 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);
+ mutex_unlock(&intf->beacon_skb_mutex);
+
return 0;
}
--
1.6.3.3
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