Do not try to connect with zero-length SSID

It was possible to find a BSS to local network profile match for a BSS
entry that has no known SSID when going through some of the SSID
wildcard cases. At leas the OWE transition mode case without BSSID match
could result in hitting this. Zero-length SSID (i.e., wildcard SSID) is
not valid in (Re)Association Request frame, so such an association will
fail. Skip such a BSS to avoid known-to-be-failing association attempts.

Signed-off-by: Jouni Malinen <jouni@codeaurora.org>

wpa_supplicant/events.c

@@ -1451,6 +1451,13 @@ skip_assoc_disallow:
 	}
 #endif /* CONFIG_SAE_PK */
 
+	if (bss->ssid_len == 0) {
+		if (debug_print)
+			wpa_dbg(wpa_s, MSG_DEBUG,
+				"   skip - no SSID known for the BSS");
+		return false;
+	}
+
 	/* Matching configuration found */
 	return true;
 }