[sms] Fix memory leak
diff --git a/src/gsm_04_11.c b/src/gsm_04_11.c
index e94f9ad..35fc12e 100644
--- a/src/gsm_04_11.c
+++ b/src/gsm_04_11.c
@@ -105,6 +105,7 @@
 
 	dispatch_signal(SS_SMS, 0, sms);
 
+	free(sms->user_data);
 	free(sms);
 
 	return 0;