From f4eaacd0ec5efc0d21fad2fb6e2e687e0a8ab8dd Mon Sep 17 00:00:00 2001
From: Benjamin Berg <bberg@redhat.com>
Date: Fri, 4 Dec 2020 18:22:04 +0100
Subject: [PATCH] pam: Return a fixed string about protocol error if there is
 no message

This can only happen if fprintd is not adhering to the protocol.
---
 pam/pam_fprintd.c | 4 ++++
 1 file changed, 4 insertions(+)

diff --git a/pam/pam_fprintd.c b/pam/pam_fprintd.c
index 8449875..eb43c34 100644
--- a/pam/pam_fprintd.c
+++ b/pam/pam_fprintd.c
@@ -202,6 +202,10 @@ verify_result (sd_bus_message *m,
 	}
 
 	msg = verify_result_str_to_msg (result, data->is_swipe);
+	if (!msg) {
+		data->result = strdup ("Protocol error with fprintd!");
+		return 0;
+	}
 	send_err_msg (data->pamh, msg);
 
 	return 0;