From 501690d312dee7f7dc17b2b1edde796fa17c3d7c Mon Sep 17 00:00:00 2001
From: "Roger A. Light" <roger@atchoo.org>
Date: Wed, 28 Apr 2021 09:21:50 +0100
Subject: [PATCH] Handle identifier==NULL case.

---
 src/plugin.c | 4 +++-
 1 file changed, 3 insertions(+), 1 deletion(-)

diff --git a/src/plugin.c b/src/plugin.c
index 45fc8c99..fbf3bd7d 100644
--- a/src/plugin.c
+++ b/src/plugin.c
@@ -274,7 +274,9 @@ int mosquitto_callback_unregister(
 	struct mosquitto__callback **cb_base = NULL;
 	struct mosquitto__security_options *security_options;
 
-	if(cb_func == NULL) return MOSQ_ERR_INVAL;
+	if(identifier == NULL || cb_func == NULL){
+		return MOSQ_ERR_INVAL;
+	}
 
 	if(identifier->listener == NULL){
 		security_options = &db.config->security_options;