nl80211: Convert sched_scan_req pointer to RCU pointer

Because of possible races when accessing sched_scan_req pointer in
rdev, the sched_scan_req is converted to RCU pointer.

Signed-off-by: Jukka Rissanen <jukka.rissanen@linux.intel.com>
Signed-off-by: Johannes Berg <johannes.berg@intel.com>

diff --git a/include/net/cfg80211.h b/include/net/cfg80211.h
index 4bc1fc9..45d4d72 100644 (file)
--- a/include/net/cfg80211.h
+++ b/include/net/cfg80211.h
@@ -1516,6 +1516,7 @@ struct cfg80211_match_set {
  * @mac_addr_mask: MAC address mask used with randomisation, bits that
  *     are 0 in the mask should be randomised, bits that are 1 should
  *     be taken from the @mac_addr
+ * @rcu_head: RCU callback used to free the struct
  */
 struct cfg80211_sched_scan_request {
        struct cfg80211_ssid *ssids;
@@ -1537,6 +1538,7 @@ struct cfg80211_sched_scan_request {
        struct wiphy *wiphy;
        struct net_device *dev;
        unsigned long scan_start;
+       struct rcu_head rcu_head;
 
        /* keep last */
        struct ieee80211_channel *channels[0];

diff --git a/net/wireless/core.c b/net/wireless/core.c
index b661fcc..0743449 100644 (file)
--- a/net/wireless/core.c
+++ b/net/wireless/core.c
@@ -867,6 +867,7 @@ void __cfg80211_leave(struct cfg80211_registered_device *rdev,
                      struct wireless_dev *wdev)
 {
        struct net_device *dev = wdev->netdev;
+       struct cfg80211_sched_scan_request *sched_scan_req;
 
        ASSERT_RTNL();
        ASSERT_WDEV_LOCK(wdev);
@@ -877,7 +878,8 @@ void __cfg80211_leave(struct cfg80211_registered_device *rdev,
                break;
        case NL80211_IFTYPE_P2P_CLIENT:
        case NL80211_IFTYPE_STATION:
-               if (rdev->sched_scan_req && dev == rdev->sched_scan_req->dev)
+               sched_scan_req = rtnl_dereference(rdev->sched_scan_req);
+               if (sched_scan_req && dev == sched_scan_req->dev)
                        __cfg80211_stop_sched_scan(rdev, false);
 
 #ifdef CONFIG_CFG80211_WEXT
@@ -956,6 +958,7 @@ static int cfg80211_netdev_notifier_call(struct notifier_block *nb,
        struct net_device *dev = netdev_notifier_info_to_dev(ptr);
        struct wireless_dev *wdev = dev->ieee80211_ptr;
        struct cfg80211_registered_device *rdev;
+       struct cfg80211_sched_scan_request *sched_scan_req;
 
        if (!wdev)
                return NOTIFY_DONE;
@@ -1021,8 +1024,9 @@ static int cfg80211_netdev_notifier_call(struct notifier_block *nb,
                        ___cfg80211_scan_done(rdev, false);
                }
 
-               if (WARN_ON(rdev->sched_scan_req &&
-                           rdev->sched_scan_req->dev == wdev->netdev)) {
+               sched_scan_req = rtnl_dereference(rdev->sched_scan_req);
+               if (WARN_ON(sched_scan_req &&
+                           sched_scan_req->dev == wdev->netdev)) {
                        __cfg80211_stop_sched_scan(rdev, false);
                }
 

diff --git a/net/wireless/core.h b/net/wireless/core.h
index e87cae5..e82030c 100644 (file)
--- a/net/wireless/core.h
+++ b/net/wireless/core.h
@@ -70,7 +70,7 @@ struct cfg80211_registered_device {
        u32 bss_generation;
        struct cfg80211_scan_request *scan_req; /* protected by RTNL */
        struct sk_buff *scan_msg;
-       struct cfg80211_sched_scan_request *sched_scan_req;
+       struct cfg80211_sched_scan_request __rcu *sched_scan_req;
        unsigned long suspend_at;
        struct work_struct scan_done_wk;
        struct work_struct sched_scan_results_wk;

diff --git a/net/wireless/nl80211.c b/net/wireless/nl80211.c
index 5b1907f..bacdf22 100644 (file)
--- a/net/wireless/nl80211.c
+++ b/net/wireless/nl80211.c
@@ -6190,6 +6190,7 @@ static int nl80211_start_sched_scan(struct sk_buff *skb,
        struct cfg80211_registered_device *rdev = info->user_ptr[0];
        struct net_device *dev = info->user_ptr[1];
        struct wireless_dev *wdev = dev->ieee80211_ptr;
+       struct cfg80211_sched_scan_request *sched_scan_req;
        int err;
 
        if (!(rdev->wiphy.flags & WIPHY_FLAG_SUPPORTS_SCHED_SCAN) ||
@@ -6199,27 +6200,29 @@ static int nl80211_start_sched_scan(struct sk_buff *skb,
        if (rdev->sched_scan_req)
                return -EINPROGRESS;
 
-       rdev->sched_scan_req = nl80211_parse_sched_scan(&rdev->wiphy, wdev,
-                                                       info->attrs);
-       err = PTR_ERR_OR_ZERO(rdev->sched_scan_req);
+       sched_scan_req = nl80211_parse_sched_scan(&rdev->wiphy, wdev,
+                                                 info->attrs);
+
+       err = PTR_ERR_OR_ZERO(sched_scan_req);
        if (err)
                goto out_err;
 
-       err = rdev_sched_scan_start(rdev, dev, rdev->sched_scan_req);
+       err = rdev_sched_scan_start(rdev, dev, sched_scan_req);
        if (err)
                goto out_free;
 
-       rdev->sched_scan_req->dev = dev;
-       rdev->sched_scan_req->wiphy = &rdev->wiphy;
+       sched_scan_req->dev = dev;
+       sched_scan_req->wiphy = &rdev->wiphy;
+
+       rcu_assign_pointer(rdev->sched_scan_req, sched_scan_req);
 
        nl80211_send_sched_scan(rdev, dev,
                                NL80211_CMD_START_SCHED_SCAN);
        return 0;
 
 out_free:
-       kfree(rdev->sched_scan_req);
+       kfree(sched_scan_req);
 out_err:
-       rdev->sched_scan_req = NULL;
        return err;
 }
 

diff --git a/net/wireless/scan.c b/net/wireless/scan.c
index bda39f1..c705c3e 100644 (file)
--- a/net/wireless/scan.c
+++ b/net/wireless/scan.c
@@ -257,7 +257,7 @@ void __cfg80211_sched_scan_results(struct work_struct *wk)
 
        rtnl_lock();
 
-       request = rdev->sched_scan_req;
+       request = rtnl_dereference(rdev->sched_scan_req);
 
        /* we don't have sched_scan_req anymore if the scan is stopping */
        if (request) {
@@ -279,7 +279,8 @@ void cfg80211_sched_scan_results(struct wiphy *wiphy)
 {
        trace_cfg80211_sched_scan_results(wiphy);
        /* ignore if we're not scanning */
-       if (wiphy_to_rdev(wiphy)->sched_scan_req)
+
+       if (rcu_access_pointer(wiphy_to_rdev(wiphy)->sched_scan_req))
                queue_work(cfg80211_wq,
                           &wiphy_to_rdev(wiphy)->sched_scan_results_wk);
 }
@@ -308,6 +309,7 @@ EXPORT_SYMBOL(cfg80211_sched_scan_stopped);
 int __cfg80211_stop_sched_scan(struct cfg80211_registered_device *rdev,
                               bool driver_initiated)
 {
+       struct cfg80211_sched_scan_request *sched_scan_req;
        struct net_device *dev;
 
        ASSERT_RTNL();
@@ -315,7 +317,8 @@ int __cfg80211_stop_sched_scan(struct cfg80211_registered_device *rdev,
        if (!rdev->sched_scan_req)
                return -ENOENT;
 
-       dev = rdev->sched_scan_req->dev;
+       sched_scan_req = rtnl_dereference(rdev->sched_scan_req);
+       dev = sched_scan_req->dev;
 
        if (!driver_initiated) {
                int err = rdev_sched_scan_stop(rdev, dev);
@@ -325,8 +328,8 @@ int __cfg80211_stop_sched_scan(struct cfg80211_registered_device *rdev,
 
        nl80211_send_sched_scan(rdev, dev, NL80211_CMD_SCHED_SCAN_STOPPED);
 
-       kfree(rdev->sched_scan_req);
-       rdev->sched_scan_req = NULL;
+       RCU_INIT_POINTER(rdev->sched_scan_req, NULL);
+       kfree_rcu(sched_scan_req, rcu_head);
 
        return 0;
 }