File bind-CVE-2018-5743.patch of Package bind.29689

From 9689ffc485df8f971f0ad81ab8ab1f5389493776 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Witold=20Kr=C4=99cicki?= <wpk@isc.org>
Date: Thu, 3 Jan 2019 14:17:43 +0100
Subject: [PATCH] fix enforcement of tcp-clients (v1)

tcp-clients settings could be exceeded in some cases by
creating more and more active TCP clients that are over
the set quota limit, which in the end could lead to a
DoS attack by e.g. exhaustion of file descriptors.

If TCP client we're closing went over the quota (so it's
not attached to a quota) mark it as mortal - so that it
will be destroyed and not set up to listen for new
connections - unless it's the last client for a specific
interface.

(cherry picked from commit f97131d21b97381cef72b971b157345c1f9b4115)
---
 bin/named/client.c | 13 ++++++++++++-
 1 file changed, 12 insertions(+), 1 deletion(-)

--- bin/named/client.c.orig
+++ bin/named/client.c
@@ -398,8 +398,19 @@ exit_check(ns_client_t *client) {
 			isc_socket_detach(&client->tcpsocket);
 		}
 
-		if (client->tcpquota != NULL)
+		if (client->tcpquota != NULL) {
 			isc_quota_detach(&client->tcpquota);
+		} else {
+			/*
+			 * We went over quota with this client, we don't
+			 * want to restart listening unless this is the
+			 * last client on this interface, which is
+			 * checked later.
+			 */
+			if (TCP_CLIENT(client)) {
+				client->mortal = ISC_TRUE;
+			}
+		}
 
 		if (client->timerset) {
 			(void)isc_timer_reset(client->timer,