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Upstream-Status: Backport [https://ftp.isc.org/isc/bind9/9.11.4-P1/patches/CVE-2018-5740]
CVE: CVE-2018-5740
Signed-off-by: Changqing Li <changqing.li@windriver.com>
diff --git a/CHANGES b/CHANGES
index 750b600..3d8d655 100644
--- a/CHANGES
+++ b/CHANGES
@@ -1,3 +1,9 @@
+ --- 9.11.4-P1 released ---
+
+4997. [security] named could crash during recursive processing
+ of DNAME records when "deny-answer-aliases" was
+ in use. (CVE-2018-5740) [GL #387]
+
--- 9.11.4 released ---
--- 9.11.4rc2 released ---
diff --git a/lib/dns/resolver.c b/lib/dns/resolver.c
index 8f674a2..41d1385 100644
--- a/lib/dns/resolver.c
+++ b/lib/dns/resolver.c
@@ -6318,6 +6318,7 @@ is_answertarget_allowed(fetchctx_t *fctx, dns_name_t *qname, dns_name_t *rname,
unsigned int nlabels;
dns_fixedname_t fixed;
dns_name_t prefix;
+ int order;
REQUIRE(rdataset != NULL);
REQUIRE(rdataset->type == dns_rdatatype_cname ||
@@ -6340,17 +6341,25 @@ is_answertarget_allowed(fetchctx_t *fctx, dns_name_t *qname, dns_name_t *rname,
tname = &cname.cname;
break;
case dns_rdatatype_dname:
+ if (dns_name_fullcompare(qname, rname, &order, &nlabels) !=
+ dns_namereln_subdomain)
+ {
+ return (ISC_TRUE);
+ }
result = dns_rdata_tostruct(&rdata, &dname, NULL);
RUNTIME_CHECK(result == ISC_R_SUCCESS);
dns_name_init(&prefix, NULL);
tname = dns_fixedname_initname(&fixed);
- nlabels = dns_name_countlabels(qname) -
- dns_name_countlabels(rname);
+ nlabels = dns_name_countlabels(rname);
dns_name_split(qname, nlabels, &prefix, NULL);
result = dns_name_concatenate(&prefix, &dname.dname, tname,
NULL);
- if (result == DNS_R_NAMETOOLONG)
+ if (result == DNS_R_NAMETOOLONG) {
+ if (chainingp != NULL) {
+ *chainingp = ISC_TRUE;
+ }
return (ISC_TRUE);
+ }
RUNTIME_CHECK(result == ISC_R_SUCCESS);
break;
default:
@@ -7071,7 +7080,9 @@ answer_response(fetchctx_t *fctx) {
}
if ((ardataset->type == dns_rdatatype_cname ||
ardataset->type == dns_rdatatype_dname) &&
- !is_answertarget_allowed(fctx, qname, aname, ardataset,
+ type != ardataset->type &&
+ type != dns_rdatatype_any &&
+ !is_answertarget_allowed(fctx, qname, aname, ardataset,
NULL))
{
return (DNS_R_SERVFAIL);
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