wifi: cfg80211: check BSSID Index against MaxBSSID

Add a verification that the BSSID Index does not exceed the maximum
number of BSSIDs in the Multiple-BSSID set.
Signed-off-by: Benjamin Berg <benjamin.berg@intel.com>
Reviewed-by: Johannes Berg <johannes.berg@intel.com>
Signed-off-by: Miri Korenblit <miriam.rachel.korenblit@intel.com>
Link: https://msgid.link/20240318184907.a7574d415adc.I02f40c2920a9f602898190679cc27d0c8ee2c67d@changeidSigned-off-by: Johannes Berg <johannes.berg@intel.com>

net/wireless/scan.c

@@ -2447,7 +2447,8 @@ cfg80211_parse_mbssid_data(struct wiphy *wiphy,
 				 profile, profile_len);
 			if (!mbssid_index_ie || mbssid_index_ie[1] < 1 ||
 			    mbssid_index_ie[2] == 0 ||
-			    mbssid_index_ie[2] > 46) {
+			    mbssid_index_ie[2] > 46 ||
+			    mbssid_index_ie[2] >= (1 << elem->data[0])) {
 				/* No valid Multiple BSSID-Index element */
 				continue;
 			}