From 462175659674a10c0d39c7c328f1a5324ce2e38b Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Micha=C5=82=20K=C4=99pie=C5=84?= <michal@isc.org>
Date: Tue, 13 Nov 2018 13:50:47 +0100
Subject: [PATCH 3022/3677] Fix a shutdown race in bin/dig/dighost.c

If a tool using the routines defined in bin/dig/dighost.c is sent an
interruption signal around the time a connection timeout is scheduled to
fire, connect_timeout() may be executed after destroy_libs() detaches
from the global task (setting 'global_task' to NULL), which results in a
crash upon a UDP retry due to bringup_timer() attempting to create a
timer with 'task' set to NULL.  Fix by preventing connect_timeout() from
attempting a retry when shutdown is in progress.
---
 bin/dig/dighost.c | 5 +++++
 1 file changed, 5 insertions(+)

diff --git a/bin/dig/dighost.c b/bin/dig/dighost.c
index f4e5e55..410b634 100644
--- a/bin/dig/dighost.c
+++ b/bin/dig/dighost.c
@@ -2902,6 +2902,11 @@ connect_timeout(isc_task_t *task, isc_event_t *event) {
 
 	INSIST(!free_now);
 
+	if (cancel_now) {
+		UNLOCK_LOOKUP;
+		return;
+	}
+
 	if ((query != NULL) && (query->lookup->current_query != NULL) &&
 	    ISC_LINK_LINKED(query->lookup->current_query, link) &&
 	    (ISC_LIST_NEXT(query->lookup->current_query, link) != NULL)) {
-- 
1.8.3.1

