mac80211: fix race in TKIP MIC test debugfs file

Accessing sdata->vif.bss_conf.bssid without any
protection here is racy, use u.mgd.associated
instead and lock the correct mutex for it.

Signed-off-by: Johannes Berg <johannes.berg@intel.com>
diff --git a/net/mac80211/debugfs_netdev.c b/net/mac80211/debugfs_netdev.c
index 4b68ec7..99ce871 100644
--- a/net/mac80211/debugfs_netdev.c
+++ b/net/mac80211/debugfs_netdev.c
@@ -284,13 +284,16 @@
 	case NL80211_IFTYPE_STATION:
 		fc |= cpu_to_le16(IEEE80211_FCTL_TODS);
 		/* BSSID SA DA */
-		if (sdata->vif.bss_conf.bssid == NULL) {
+		mutex_lock(&sdata->u.mgd.mtx);
+		if (!sdata->u.mgd.associated) {
+			mutex_unlock(&sdata->u.mgd.mtx);
 			dev_kfree_skb(skb);
 			return -ENOTCONN;
 		}
-		memcpy(hdr->addr1, sdata->vif.bss_conf.bssid, ETH_ALEN);
+		memcpy(hdr->addr1, sdata->u.mgd.associated->bssid, ETH_ALEN);
 		memcpy(hdr->addr2, sdata->vif.addr, ETH_ALEN);
 		memcpy(hdr->addr3, addr, ETH_ALEN);
+		mutex_unlock(&sdata->u.mgd.mtx);
 		break;
 	default:
 		dev_kfree_skb(skb);