mac80211: don't look at the PM bit of BAR frames

commit 769dc04d upstream.

When a peer sends a BAR frame with PM bit clear, we should
not modify its PM state as madated by the spec in
802.11-20012 10.2.1.2.
Signed-off-by: Emmanuel Grumbach <emmanuel.grumbach@intel.com>
Signed-off-by: Johannes Berg <johannes.berg@intel.com>
Signed-off-by: Ben Hutchings <ben@decadent.org.uk>

net/mac80211/rx.c

@@ -1287,12 +1287,16 @@ ieee80211_rx_h_sta_process(struct ieee80211_rx_data *rx)
 	 */
 	if (!(sta->local->hw.flags & IEEE80211_HW_AP_LINK_PS) &&
 	    !ieee80211_has_morefrags(hdr->frame_control) &&
+	    !ieee80211_is_back_req(hdr->frame_control) &&
 	    !(status->rx_flags & IEEE80211_RX_DEFERRED_RELEASE) &&
 	    (rx->sdata->vif.type == NL80211_IFTYPE_AP ||
 	     rx->sdata->vif.type == NL80211_IFTYPE_AP_VLAN) &&
-	    /* PM bit is only checked in frames where it isn't reserved,
+	    /*
+	     * PM bit is only checked in frames where it isn't reserved,
 	     * in AP mode it's reserved in non-bufferable management frames
 	     * (cf. IEEE 802.11-2012 8.2.4.1.7 Power Management field)
+	     * BAR frames should be ignored as specified in
+	     * IEEE 802.11-2012 10.2.1.2.
 	     */
 	    (!ieee80211_is_mgmt(hdr->frame_control) ||
 	     ieee80211_is_bufferable_mmpdu(hdr->frame_control))) {