mac80211: fix control port tx status check

The initial control port tx status patch assumed, that
we have IEEE 802.11 frames, but actually ethernet frames
are stored in the ack skb. Fix this by checking for the
correct ethertype and skb protocol 802.3.

Also allow tx status reports for ETH_P_PREAUTH, as preauth
frames can also be send over the nl80211 control port.

Fixes: a7528198 ("mac80211: support control port TX status reporting")
Reported-by: Jouni Malinen <j@w1.fi>
Signed-off-by: Markus Theil <markus.theil@tu-ilmenau.de>
Reported-by: kernel test robot <lkp@intel.com>
Link: https://lore.kernel.org/r/20200622123542.173695-1-markus.theil@tu-ilmenau.deSigned-off-by: Johannes Berg <johannes.berg@intel.com>

net/mac80211/status.c

@@ -639,11 +639,23 @@ static void ieee80211_report_ack_skb(struct ieee80211_local *local,
 		u64 cookie = IEEE80211_SKB_CB(skb)->ack.cookie;
 		struct ieee80211_sub_if_data *sdata;
 		struct ieee80211_hdr *hdr = (void *)skb->data;
+		__be16 ethertype = 0;
+
+		if (skb->len >= ETH_HLEN && skb->protocol == cpu_to_be16(ETH_P_802_3))
+			skb_copy_bits(skb, 2 * ETH_ALEN, &ethertype, ETH_TLEN);
 
 		rcu_read_lock();
 		sdata = ieee80211_sdata_from_skb(local, skb);
 		if (sdata) {
-			if (ieee80211_is_any_nullfunc(hdr->frame_control))
+			if (ethertype == sdata->control_port_protocol ||
+			    ethertype == cpu_to_be16(ETH_P_PREAUTH))
+				cfg80211_control_port_tx_status(&sdata->wdev,
+								cookie,
+								skb->data,
+								skb->len,
+								acked,
+								GFP_ATOMIC);
+			else if (ieee80211_is_any_nullfunc(hdr->frame_control))
 				cfg80211_probe_status(sdata->dev, hdr->addr1,
 						      cookie, acked,
 						      info->status.ack_signal,
@@ -654,12 +666,8 @@ static void ieee80211_report_ack_skb(struct ieee80211_local *local,
 							skb->data, skb->len,
 							acked, GFP_ATOMIC);
 			else
-				cfg80211_control_port_tx_status(&sdata->wdev,
-								cookie,
-								skb->data,
-								skb->len,
-								acked,
-								GFP_ATOMIC);
+				pr_warn("Unknown status report in ack skb\n");
+
 		}
 		rcu_read_unlock();