iwlwifi: mvm: refuse connection to APs with BI < 16

commit 48bc1307 upstream.

Due to a firmware bug, it crashes when the beacon interval
is smaller than 16. Avoid this by refusing the station state
change creating the AP station, causing mac80211 to abandon
the attempt to connect to the AP, and eventually wpa_s to
blacklist it.
Reviewed-by: Emmanuel Grumbach <emmanuel.grumbach@intel.com>
Signed-off-by: Johannes Berg <johannes.berg@intel.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

drivers/net/wireless/iwlwifi/mvm/mac80211.c

@@ -987,6 +987,21 @@ static int iwl_mvm_mac_sta_state(struct ieee80211_hw *hw,
 	mutex_lock(&mvm->mutex);
 	if (old_state == IEEE80211_STA_NOTEXIST &&
 	    new_state == IEEE80211_STA_NONE) {
+		/*
+		 * Firmware bug - it'll crash if the beacon interval is less
+		 * than 16. We can't avoid connecting at all, so refuse the
+		 * station state change, this will cause mac80211 to abandon
+		 * attempts to connect to this AP, and eventually wpa_s will
+		 * blacklist the AP...
+		 */
+		if (vif->type == NL80211_IFTYPE_STATION &&
+		    vif->bss_conf.beacon_int < 16) {
+			IWL_ERR(mvm,
+				"AP %pM beacon interval is %d, refusing due to firmware bug!\n",
+				sta->addr, vif->bss_conf.beacon_int);
+			ret = -EINVAL;
+			goto out_unlock;
+		}
 		ret = iwl_mvm_add_sta(mvm, vif, sta);
 	} else if (old_state == IEEE80211_STA_NONE &&
 		   new_state == IEEE80211_STA_AUTH) {
@@ -1015,6 +1030,7 @@ static int iwl_mvm_mac_sta_state(struct ieee80211_hw *hw,
 	} else {
 		ret = -EIO;
 	}
+ out_unlock:
 	mutex_unlock(&mvm->mutex);
 
 	return ret;