mac80211: fix crash with P2P Device returning action frames

If a P2P Device interface receives an unhandled action
frame, we attempt to return it. This crashes because it
doesn't have a channel context. Fix the crash by using
status->band and properly mark the return frame as an
off-channel frame.

Reported-by: Ilan Peer <ilan.peer@intel.com>
Reviewed-by: Ilan Peer <ilan.peer@intel.com>
Signed-off-by: Johannes Berg <johannes.berg@intel.com>

net/mac80211/rx.c

@@ -2675,7 +2675,19 @@ ieee80211_rx_h_action_return(struct ieee80211_rx_data *rx)
 
 		memset(nskb->cb, 0, sizeof(nskb->cb));
 
-		ieee80211_tx_skb(rx->sdata, nskb);
+		if (rx->sdata->vif.type == NL80211_IFTYPE_P2P_DEVICE) {
+			struct ieee80211_tx_info *info = IEEE80211_SKB_CB(nskb);
+
+			info->flags = IEEE80211_TX_CTL_TX_OFFCHAN |
+				      IEEE80211_TX_INTFL_OFFCHAN_TX_OK |
+				      IEEE80211_TX_CTL_NO_CCK_RATE;
+			if (local->hw.flags & IEEE80211_HW_QUEUE_CONTROL)
+				info->hw_queue =
+					local->hw.offchannel_tx_hw_queue;
+		}
+
+		__ieee80211_tx_skb_tid_band(rx->sdata, nskb, 7,
+					    status->band);
 	}
 	dev_kfree_skb(rx->skb);
 	return RX_QUEUED;