fix potential memory leak + improved error checking

PR: 1182

crypto/x509v3/v3_cpols.c

@@ -139,7 +139,15 @@ static STACK_OF(POLICYINFO) *r2i_certpol(X509V3_EXT_METHOD *method,
 	CONF_VALUE *cnf;
 	int i, ia5org;
 	pols = sk_POLICYINFO_new_null();
+	if (pols == NULL) {
+		X509V3err(X509V3_F_R2I_CERTPOL, ERR_R_MALLOC_FAILURE);
+		return NULL;
+	}
 	vals =  X509V3_parse_list(value);
+	if (vals == NULL) {
+		X509V3err(X509V3_F_R2I_CERTPOL, ERR_R_X509V3_LIB);
+		goto err;
+	}
 	ia5org = 0;
 	for(i = 0; i < sk_CONF_VALUE_num(vals); i++) {
 		cnf = sk_CONF_VALUE_value(vals, i);
@@ -178,6 +186,7 @@ static STACK_OF(POLICYINFO) *r2i_certpol(X509V3_EXT_METHOD *method,
 	sk_CONF_VALUE_pop_free(vals, X509V3_conf_free);
 	return pols;
 	err:
+	sk_CONF_VALUE_pop_free(vals, X509V3_conf_free);
 	sk_POLICYINFO_pop_free(pols, POLICYINFO_free);
 	return NULL;
 }