Fixed EAP-TTLS server to verify eap_ttls_phase2_eap_init() return code

It is possible that the initialization of the Phase 2 EAP method fails and
if that happens, we need to stop EAP-TTLS server from trying to continue
using the uninitialized EAP method. Otherwise, the server could trigger
a segmentation fault when dereferencing a NULL pointer.

src/eap_server/eap_ttls.c

@@ -991,7 +991,13 @@ static void eap_ttls_process_phase2_eap_response(struct eap_sm *sm,
 				sm->user_eap_method_index++].method;
 			wpa_printf(MSG_DEBUG, "EAP-TTLS: try EAP type %d",
 				   next_type);
-			eap_ttls_phase2_eap_init(sm, data, next_type);
+			if (eap_ttls_phase2_eap_init(sm, data, next_type)) {
+				wpa_printf(MSG_DEBUG, "EAP-TTLS: Failed to "
+					   "initialize EAP type %d",
+					   next_type);
+				eap_ttls_state(data, FAILURE);
+				return;
+			}
 		} else {
 			eap_ttls_state(data, FAILURE);
 		}
@@ -1061,7 +1067,11 @@ static void eap_ttls_process_phase2_eap_response(struct eap_sm *sm,
 		break;
 	}
 
-	eap_ttls_phase2_eap_init(sm, data, next_type);
+	if (eap_ttls_phase2_eap_init(sm, data, next_type)) {
+		wpa_printf(MSG_DEBUG, "EAP-TTLS: Failed to initialize EAP "
+			   "type %d", next_type);
+		eap_ttls_state(data, FAILURE);
+	}
 }