File _service:obs_scm:backport-CVE-2022-2795.patch of Package dhcp

Reference:http://downloads.isc.org/isc/bind/9.16.33/patches/0001-CVE-2022-2795.patch

diff --git a/bind/bind-9.11.36/lib/dns/resolver.c b/bind/bind-9.11.36/lib/dns/resolver.c
index d2cf14bbc8b..73a0ee9f779 100644
--- a/bind/bind-9.11.36/lib/dns/resolver.c
+++ b/bind/bind-9.11.36/lib/dns/resolver.c
@@ -195,6 +195,12 @@
  */
 #define NS_FAIL_LIMIT 4
 #define NS_RR_LIMIT   5
+/*
+ * IP address lookups are performed for at most NS_PROCESSING_LIMIT NS RRs in
+ * any NS RRset encountered, to avoid excessive resource use while processing
+ * large delegations.
+ */
+#define NS_PROCESSING_LIMIT 20
 
 /* Number of hash buckets for zone counters */
 #ifndef RES_DOMAIN_BUCKETS
@@ -3711,6 +3717,7 @@ fctx_getaddresses(fetchctx_t *fctx, bool badcache) {
 	bool need_alternate = false;
 	bool all_spilled = true;
 	unsigned int no_addresses = 0;
+	unsigned int ns_processed = 0;
 
 	FCTXTRACE5("getaddresses", "fctx->depth=", fctx->depth);
 
@@ -3902,6 +3909,11 @@ fctx_getaddresses(fetchctx_t *fctx, bool badcache) {
 
 		dns_rdata_reset(&rdata);
 		dns_rdata_freestruct(&ns);
+
+		if (++ns_processed >= NS_PROCESSING_LIMIT) {
+			result = ISC_R_NOMORE;
+			break;
+		}
 	}
 	if (result != ISC_R_NOMORE) {
 		return (result);