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From c1d0599a246f646d1c22018f8fa09459270a44b8 Mon Sep 17 00:00:00 2001
From: Mark Andrews <marka@isc.org>
Date: Fri, 21 Oct 2016 14:55:10 +1100
Subject: [PATCH] 4489. [security] It was possible to trigger assertions when
processing a response. (CVE-2016-8864) [RT #43465]
(cherry picked from commit bd6f27f5c353133b563fe69100b2f168c129f3ca)
Upstream-Status: Backport
[https://source.isc.org/cgi-bin/gitweb.cgi?p=bind9.git;a=commit;h=c1d0599a246f646d1c22018f8fa09459270a44b8]
CVE: CVE-2016-8864
Signed-off-by: Yi Zhao <yi.zhao@windriver.com>
---
CHANGES | 3 +++
lib/dns/resolver.c | 69 +++++++++++++++++++++++++++++++++++++-----------------
2 files changed, 50 insertions(+), 22 deletions(-)
diff --git a/CHANGES b/CHANGES
index 5c8c61a..41cfce5 100644
--- a/CHANGES
+++ b/CHANGES
@@ -1,3 +1,6 @@
+4489. [security] It was possible to trigger assertions when processing
+ a response. (CVE-2016-8864) [RT #43465]
+
4467. [security] It was possible to trigger an assertion when
rendering a message. (CVE-2016-2776) [RT #43139]
diff --git a/lib/dns/resolver.c b/lib/dns/resolver.c
index ba1ae23..13c8b44 100644
--- a/lib/dns/resolver.c
+++ b/lib/dns/resolver.c
@@ -612,7 +612,9 @@ valcreate(fetchctx_t *fctx, dns_adbaddrinfo_t *addrinfo, dns_name_t *name,
valarg->addrinfo = addrinfo;
if (!ISC_LIST_EMPTY(fctx->validators))
- INSIST((valoptions & DNS_VALIDATOR_DEFER) != 0);
+ valoptions |= DNS_VALIDATOR_DEFER;
+ else
+ valoptions &= ~DNS_VALIDATOR_DEFER;
result = dns_validator_create(fctx->res->view, name, type, rdataset,
sigrdataset, fctx->rmessage,
@@ -5526,13 +5528,6 @@ cache_name(fetchctx_t *fctx, dns_name_t *name, dns_adbaddrinfo_t *addrinfo,
rdataset,
sigrdataset,
valoptions, task);
- /*
- * Defer any further validations.
- * This prevents multiple validators
- * from manipulating fctx->rmessage
- * simultaneously.
- */
- valoptions |= DNS_VALIDATOR_DEFER;
}
} else if (CHAINING(rdataset)) {
if (rdataset->type == dns_rdatatype_cname)
@@ -5647,6 +5642,11 @@ cache_name(fetchctx_t *fctx, dns_name_t *name, dns_adbaddrinfo_t *addrinfo,
eresult == DNS_R_NCACHENXRRSET);
}
event->result = eresult;
+ if (adbp != NULL && *adbp != NULL) {
+ if (anodep != NULL && *anodep != NULL)
+ dns_db_detachnode(*adbp, anodep);
+ dns_db_detach(adbp);
+ }
dns_db_attach(fctx->cache, adbp);
dns_db_transfernode(fctx->cache, &node, anodep);
clone_results(fctx);
@@ -5897,6 +5897,11 @@ ncache_message(fetchctx_t *fctx, dns_adbaddrinfo_t *addrinfo,
fctx->attributes |= FCTX_ATTR_HAVEANSWER;
if (event != NULL) {
event->result = eresult;
+ if (adbp != NULL && *adbp != NULL) {
+ if (anodep != NULL && *anodep != NULL)
+ dns_db_detachnode(*adbp, anodep);
+ dns_db_detach(adbp);
+ }
dns_db_attach(fctx->cache, adbp);
dns_db_transfernode(fctx->cache, &node, anodep);
clone_results(fctx);
@@ -6718,13 +6723,15 @@ static isc_result_t
answer_response(fetchctx_t *fctx) {
isc_result_t result;
dns_message_t *message;
- dns_name_t *name, *dname, *qname, tname, *ns_name;
+ dns_name_t *name, *dname = NULL, *qname, *dqname, tname, *ns_name;
+ dns_name_t *cname = NULL;
dns_rdataset_t *rdataset, *ns_rdataset;
isc_boolean_t done, external, chaining, aa, found, want_chaining;
- isc_boolean_t have_answer, found_cname, found_type, wanted_chaining;
+ isc_boolean_t have_answer, found_cname, found_dname, found_type;
+ isc_boolean_t wanted_chaining;
unsigned int aflag;
dns_rdatatype_t type;
- dns_fixedname_t fdname, fqname;
+ dns_fixedname_t fdname, fqname, fqdname;
dns_view_t *view;
FCTXTRACE("answer_response");
@@ -6738,6 +6745,7 @@ answer_response(fetchctx_t *fctx) {
done = ISC_FALSE;
found_cname = ISC_FALSE;
+ found_dname = ISC_FALSE;
found_type = ISC_FALSE;
chaining = ISC_FALSE;
have_answer = ISC_FALSE;
@@ -6747,12 +6755,13 @@ answer_response(fetchctx_t *fctx) {
aa = ISC_TRUE;
else
aa = ISC_FALSE;
- qname = &fctx->name;
+ dqname = qname = &fctx->name;
type = fctx->type;
view = fctx->res->view;
+ dns_fixedname_init(&fqdname);
result = dns_message_firstname(message, DNS_SECTION_ANSWER);
while (!done && result == ISC_R_SUCCESS) {
- dns_namereln_t namereln;
+ dns_namereln_t namereln, dnamereln;
int order;
unsigned int nlabels;
@@ -6760,6 +6769,8 @@ answer_response(fetchctx_t *fctx) {
dns_message_currentname(message, DNS_SECTION_ANSWER, &name);
external = ISC_TF(!dns_name_issubdomain(name, &fctx->domain));
namereln = dns_name_fullcompare(qname, name, &order, &nlabels);
+ dnamereln = dns_name_fullcompare(dqname, name, &order,
+ &nlabels);
if (namereln == dns_namereln_equal) {
wanted_chaining = ISC_FALSE;
for (rdataset = ISC_LIST_HEAD(name->list);
@@ -6854,7 +6865,7 @@ answer_response(fetchctx_t *fctx) {
}
} else if (rdataset->type == dns_rdatatype_rrsig
&& rdataset->covers ==
- dns_rdatatype_cname
+ dns_rdatatype_cname
&& !found_type) {
/*
* We're looking for something else,
@@ -6884,11 +6895,18 @@ answer_response(fetchctx_t *fctx) {
* a CNAME or DNAME).
*/
INSIST(!external);
- if (aflag ==
- DNS_RDATASETATTR_ANSWER) {
+ if ((rdataset->type !=
+ dns_rdatatype_cname) ||
+ !found_dname ||
+ (aflag ==
+ DNS_RDATASETATTR_ANSWER))
+ {
have_answer = ISC_TRUE;
+ if (rdataset->type ==
+ dns_rdatatype_cname)
+ cname = name;
name->attributes |=
- DNS_NAMEATTR_ANSWER;
+ DNS_NAMEATTR_ANSWER;
}
rdataset->attributes |= aflag;
if (aa)
@@ -6982,11 +7000,11 @@ answer_response(fetchctx_t *fctx) {
return (DNS_R_FORMERR);
}
- if (namereln != dns_namereln_subdomain) {
+ if (dnamereln != dns_namereln_subdomain) {
char qbuf[DNS_NAME_FORMATSIZE];
char obuf[DNS_NAME_FORMATSIZE];
- dns_name_format(qname, qbuf,
+ dns_name_format(dqname, qbuf,
sizeof(qbuf));
dns_name_format(name, obuf,
sizeof(obuf));
@@ -7001,7 +7019,7 @@ answer_response(fetchctx_t *fctx) {
want_chaining = ISC_TRUE;
POST(want_chaining);
aflag = DNS_RDATASETATTR_ANSWER;
- result = dname_target(rdataset, qname,
+ result = dname_target(rdataset, dqname,
nlabels, &fdname);
if (result == ISC_R_NOSPACE) {
/*
@@ -7018,10 +7036,13 @@ answer_response(fetchctx_t *fctx) {
dname = dns_fixedname_name(&fdname);
if (!is_answertarget_allowed(view,
- qname, rdataset->type,
- dname, &fctx->domain)) {
+ dqname, rdataset->type,
+ dname, &fctx->domain))
+ {
return (DNS_R_SERVFAIL);
}
+ dqname = dns_fixedname_name(&fqdname);
+ dns_name_copy(dname, dqname, NULL);
} else {
/*
* We've found a signature that
@@ -7046,6 +7067,10 @@ answer_response(fetchctx_t *fctx) {
INSIST(!external);
if (aflag == DNS_RDATASETATTR_ANSWER) {
have_answer = ISC_TRUE;
+ found_dname = ISC_TRUE;
+ if (cname != NULL)
+ cname->attributes &=
+ ~DNS_NAMEATTR_ANSWER;
name->attributes |=
DNS_NAMEATTR_ANSWER;
}
--
2.7.4
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