mac80211: fix TX legacy rate reporting when tx_status_ext is used

The RX Radiotap header length was not calculated properly when reporting
legacy rates using tx_status_ext.

Fixes: 3d07ffca ("mac80211: add struct ieee80211_tx_status support to ieee80211_add_tx_radiotap_header")
Signed-off-by: NJohn Crispin <john@phrozen.org>
Link: https://lore.kernel.org/r/20190807075949.32414-1-john@phrozen.orgSigned-off-by: NJohannes Berg <johannes.berg@intel.com>

net/mac80211/status.c

@@ -260,9 +260,15 @@ static int ieee80211_tx_radiotap_len(struct ieee80211_tx_info *info,
 	int len = sizeof(struct ieee80211_radiotap_header);
 
 	/* IEEE80211_RADIOTAP_RATE rate */
-	if (info->status.rates[0].idx >= 0 &&
-	    !(info->status.rates[0].flags & (IEEE80211_TX_RC_MCS |
-					     IEEE80211_TX_RC_VHT_MCS)))
+	if (status && status->rate && !(status->rate->flags &
+					(RATE_INFO_FLAGS_MCS |
+					 RATE_INFO_FLAGS_60G |
+					 RATE_INFO_FLAGS_VHT_MCS |
+					 RATE_INFO_FLAGS_HE_MCS)))
+		len += 2;
+	else if (info->status.rates[0].idx >= 0 &&
+		 !(info->status.rates[0].flags &
+		   (IEEE80211_TX_RC_MCS | IEEE80211_TX_RC_VHT_MCS)))
 		len += 2;
 
 	/* IEEE80211_RADIOTAP_TX_FLAGS */