mac80211: fix CSA beacon allocation size

If the FTM responder settings are changed simultaneously with
the CSA beacon, the buffer size allocated isn't sufficient and
we'll have a heap overrun. Fix this.

While at it, also clean up the ftm_responder assignment, doing
it only if ftm_responder is non-zero is valid as it's 0 to start
with, but not really useful to understand the code.

Fixes: bc847970 ("mac80211: support FTM responder configuration/statistics")
Signed-off-by: Johannes Berg <johannes.berg@intel.com>

net/mac80211/cfg.c

@@ -2891,7 +2891,7 @@ cfg80211_beacon_dup(struct cfg80211_beacon_data *beacon)
 
 	len = beacon->head_len + beacon->tail_len + beacon->beacon_ies_len +
 	      beacon->proberesp_ies_len + beacon->assocresp_ies_len +
-	      beacon->probe_resp_len;
+	      beacon->probe_resp_len + beacon->lci_len + beacon->civicloc_len;
 
 	new_beacon = kzalloc(sizeof(*new_beacon) + len, GFP_KERNEL);
 	if (!new_beacon)
@@ -2934,8 +2934,9 @@ cfg80211_beacon_dup(struct cfg80211_beacon_data *beacon)
 		memcpy(pos, beacon->probe_resp, beacon->probe_resp_len);
 		pos += beacon->probe_resp_len;
 	}
-	if (beacon->ftm_responder)
-		new_beacon->ftm_responder = beacon->ftm_responder;
+
+	/* might copy -1, meaning no changes requested */
+	new_beacon->ftm_responder = beacon->ftm_responder;
 	if (beacon->lci) {
 		new_beacon->lci_len = beacon->lci_len;
 		new_beacon->lci = pos;