commit c56589ed1d25ae110a5b000bc1edea8f6861348f
author Simon Wunderlich <sw@simonwunderlich.de> Thu Nov 21 18:19:49 2013 +0100
committer Johannes Berg <johannes.berg@intel.com> Mon Dec 02 11:51:53 2013 +0100
tree 32545cfb3e3e7fc512a37937a71f8445877fbc5d
parent ce95320443c72ba43f8f9c6ceb276673cc30e2ce

cfg80211: protect beacon changing functions with wdev-lock

To avoid race conditions in functions which modify the beacon
information, lock these using the wdev lock. This is especially required
to avoid problems for csa handling functions which modify beacons but
can not be called under rtnl lock.

Reported-by: Johannes Berg <johannes@sipsolutions.net>
Signed-off-by: Simon Wunderlich <sw@simonwunderlich.de>
Signed-off-by: Johannes Berg <johannes.berg@intel.com>

net/wireless/nl80211.c

diff --git a/net/wireless/nl80211.c b/net/wireless/nl80211.c
index 703155b..398756c 100644
--- a/net/wireless/nl80211.c
+++ b/net/wireless/nl80211.c
@@ -3218,6 +3218,7 @@
 			return PTR_ERR(params.acl);
 	}
 
+	wdev_lock(wdev);
 	err = rdev_start_ap(rdev, dev, &params);
 	if (!err) {
 		wdev->preset_chandef = params.chandef;
@@ -3226,6 +3227,7 @@
 		wdev->ssid_len = params.ssid_len;
 		memcpy(wdev->ssid, params.ssid, wdev->ssid_len);
 	}
+	wdev_unlock(wdev);
 
 	kfree(params.acl);
 
@@ -3254,7 +3256,11 @@
 	if (err)
 		return err;
 
-	return rdev_change_beacon(rdev, dev, &params);
+	wdev_lock(wdev);
+	err = rdev_change_beacon(rdev, dev, &params);
+	wdev_unlock(wdev);
+
+	return err;
 }
 
 static int nl80211_stop_ap(struct sk_buff *skb, struct genl_info *info)
@@ -4460,7 +4466,9 @@
 {
 	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 bss_parameters params;
+	int err;
 
 	memset(&params, 0, sizeof(params));
 	/* default to not changing parameters */
@@ -4526,7 +4534,11 @@
 	    dev->ieee80211_ptr->iftype != NL80211_IFTYPE_P2P_GO)
 		return -EOPNOTSUPP;
 
-	return rdev_change_bss(rdev, dev, &params);
+	wdev_lock(wdev);
+	err = rdev_change_bss(rdev, dev, &params);
+	wdev_unlock(wdev);
+
+	return err;
 }
 
 static const struct nla_policy reg_rule_policy[NL80211_REG_RULE_ATTR_MAX + 1] = {
@@ -5791,7 +5803,11 @@
 	if (info->attrs[NL80211_ATTR_CH_SWITCH_BLOCK_TX])
 		params.block_tx = true;
 
-	return rdev_channel_switch(rdev, dev, &params);
+	wdev_lock(wdev);
+	err = rdev_channel_switch(rdev, dev, &params);
+	wdev_unlock(wdev);
+
+	return err;
 }
 
 static int nl80211_send_bss(struct sk_buff *msg, struct netlink_callback *cb,