--- gnutls-3.5.13/lib/x509/common.c	2017-03-28 19:20:50.000000000 +0200
+++ gnutls-3.5.13/lib/x509/common.c.new	2019-04-01 14:14:51.921213845 +0200
@@ -1318,6 +1318,8 @@ _gnutls_x509_get_signature(ASN1_TYPE src
 
  cleanup:
 	gnutls_free(signature->data);
+	signature->data = NULL;
+	signature->size = 0;
 	return result;
 }