Reference: https://src.fedoraproject.org/rpms/dhcp/blob/rawhide/f/0010-Handle-null-timeout.patch
From ed7610cdb2e8ebdbaee618e477879e7e008d4f29 Mon Sep 17 00:00:00 2001
From: Pavel Zhukov <pzhukov@redhat.com>
Date: Thu, 21 Feb 2019 10:29:08 +0100
Subject: [PATCH 10/26] Handle null timeout
Cc: pzhukov@redhat.com

Handle cases in add_timeout() where the function is called with a NULL
value for the 'when' parameter

ISC-Bugs: #19867 (rejected)
---
 common/dispatch.c | 4 ++++
 1 file changed, 4 insertions(+)

diff --git a/common/dispatch.c b/common/dispatch.c
index 0207ad3..d7fe200 100644
--- a/common/dispatch.c
+++ b/common/dispatch.c
@@ -209,6 +209,10 @@ void add_timeout (when, where, what, ref, unref)
 	isc_interval_t interval;
 	isc_time_t expires;
 
+	if (when == NULL) {
+		return;
+	}
+
 	/* See if this timeout supersedes an existing timeout. */
 	t = (struct timeout *)0;
 	for (q = timeouts; q; q = q->next) {
-- 
2.14.5

