wifi: mac80211: fix multi-BSSID element parsing

When parsing a frame containing a multi-BSSID element, we
need to know both the transmitted and non-transmitted BSSID
so we can parse it correctly.

Unfortunately, in quite a number of cases, we got this wrong
and were passing the wrong BSSID or useless information:
 * the mgmt->bssid from a frame is only the transmitted
   BSSID if the frame is a beacon
 * passing just one of the parameters as non-NULL isn't
   useful and ignored

In those case where we need to parse for a specific BSS we
always have a BSS structure pointer, representing the BSS
we need, whether transmitted or not. Thus, pass that pointer
to the parsing function instead of the two BSSIDs.

Also fix two bugs:
 * we need to re-parse all the elements for the other BSS
   when iterating the non-transmitted BSSes in scan
 * we need to parse for the correct BSS when setting up
   the channel data in client code

Fixes: 78ac51f81532 ("mac80211: support multi-bssid")
Signed-off-by: Johannes Berg <johannes.berg@intel.com>

1 files changed, 8 insertions, 4 deletions

diff --git a/net/mac80211/scan.c b/net/mac80211/scan.c
index f80284eee055..fa8ddf576bc1 100644
--- a/net/mac80211/scan.c
+++ b/net/mac80211/scan.c
@@ -209,8 +209,7 @@ ieee80211_bss_info_update(struct ieee80211_local *local,
 	if (baselen > len)
 		return NULL;
 
-	elems = ieee802_11_parse_elems(elements, len - baselen, false,
-				       mgmt->bssid, cbss->bssid);
+	elems = ieee802_11_parse_elems(elements, len - baselen, false, cbss);
 	if (!elems)
 		return NULL;
 
@@ -221,16 +220,21 @@ ieee80211_bss_info_update(struct ieee80211_local *local,
 
 	bss = (void *)cbss->priv;
 	ieee80211_update_bss_from_elems(local, bss, elems, rx_status, beacon);
+	kfree(elems);
 
 	list_for_each_entry(non_tx_cbss, &cbss->nontrans_list, nontrans_list) {
 		non_tx_bss = (void *)non_tx_cbss->priv;
 
+		elems = ieee802_11_parse_elems(elements, len - baselen, false,
+					       non_tx_cbss);
+		if (!elems)
+			continue;
+
 		ieee80211_update_bss_from_elems(local, non_tx_bss, elems,
 						rx_status, beacon);
+		kfree(elems);
 	}
 
-	kfree(elems);
-
 	return bss;
 }