--- /dev/null
+responses with a malformed class attribute can trigger an
+assertion failure in db.c
+
+[security]
+Insufficient testing when parsing a message allowed records with
+an incorrect class to be be accepted, triggering a REQUIRE failure
+when those records were subsequently cached. (CVE-2015-8000) [RT#4098]
+
+Upstream-Status: Backport
+
+[The patch is taken from BIND 9.9.4:
+https://bugzilla.redhat.com/attachment.cgi?id=1105581]
+
+Signed-off-by: Sona Sarmadi <sona.sarmadi@enea.com>
+---
+diff --git a/lib/dns/include/dns/message.h b/lib/dns/include/dns/message.h
+index a6862fa..d999e75 100644
+--- a/lib/dns/include/dns/message.h
++++ b/lib/dns/include/dns/message.h
+@@ -210,6 +210,8 @@ struct dns_message {
+ unsigned int verify_attempted : 1;
+ unsigned int free_query : 1;
+ unsigned int free_saved : 1;
++ unsigned int tkey : 1;
++ unsigned int rdclass_set : 1;
+
+ unsigned int opt_reserved;
+ unsigned int sig_reserved;
+@@ -1374,6 +1376,15 @@ dns_message_buildopt(dns_message_t *msg, dns_rdataset_t **opt,
+ * \li other.
+ */
+
++void
++dns_message_setclass(dns_message_t *msg, dns_rdataclass_t rdclass);
++/*%<
++ * Set the expected class of records in the response.
++ *
++ * Requires:
++ * \li msg be a valid message with parsing intent.
++ */
++
+ ISC_LANG_ENDDECLS
+
+ #endif /* DNS_MESSAGE_H */
+diff --git a/lib/dns/message.c b/lib/dns/message.c
+index 53efc5a..73def73 100644
+--- a/lib/dns/message.c
++++ b/lib/dns/message.c
+@@ -436,6 +436,8 @@ msginit(dns_message_t *m) {
+ m->saved.base = NULL;
+ m->saved.length = 0;
+ m->free_saved = 0;
++ m->tkey = 0;
++ m->rdclass_set = 0;
+ m->querytsig = NULL;
+ }
+
+@@ -1086,13 +1088,19 @@ getquestions(isc_buffer_t *source, dns_message_t *msg, dns_decompress_t *dctx,
+ * If this class is different than the one we already read,
+ * this is an error.
+ */
+- if (msg->state == DNS_SECTION_ANY) {
+- msg->state = DNS_SECTION_QUESTION;
++ if (msg->rdclass_set == 0) {
+ msg->rdclass = rdclass;
++ msg->rdclass_set = 1;
+ } else if (msg->rdclass != rdclass)
+ DO_FORMERR;
+
+ /*
++ * Is this a TKEY query?
++ */
++ if (rdtype == dns_rdatatype_tkey)
++ msg->tkey = 1;
++
++ /*
+ * Can't ask the same question twice.
+ */
+ result = dns_message_find(name, rdclass, rdtype, 0, NULL);
+@@ -1236,12 +1244,12 @@ getsection(isc_buffer_t *source, dns_message_t *msg, dns_decompress_t *dctx,
+ * If there was no question section, we may not yet have
+ * established a class. Do so now.
+ */
+- if (msg->state == DNS_SECTION_ANY &&
++ if (msg->rdclass_set == 0 &&
+ rdtype != dns_rdatatype_opt && /* class is UDP SIZE */
+ rdtype != dns_rdatatype_tsig && /* class is ANY */
+ rdtype != dns_rdatatype_tkey) { /* class is undefined */
+ msg->rdclass = rdclass;
+- msg->state = DNS_SECTION_QUESTION;
++ msg->rdclass_set = 1;
+ }
+
+ /*
+@@ -1251,7 +1259,7 @@ getsection(isc_buffer_t *source, dns_message_t *msg, dns_decompress_t *dctx,
+ if (msg->opcode != dns_opcode_update
+ && rdtype != dns_rdatatype_tsig
+ && rdtype != dns_rdatatype_opt
+- && rdtype != dns_rdatatype_dnskey /* in a TKEY query */
++ && rdtype != dns_rdatatype_key /* in a TKEY query */
+ && rdtype != dns_rdatatype_sig /* SIG(0) */
+ && rdtype != dns_rdatatype_tkey /* Win2000 TKEY */
+ && msg->rdclass != dns_rdataclass_any
+@@ -1259,6 +1267,16 @@ getsection(isc_buffer_t *source, dns_message_t *msg, dns_decompress_t *dctx,
+ DO_FORMERR;
+
+ /*
++ * If this is not a TKEY query/response then the KEY
++ * record's class needs to match.
++ */
++ if (msg->opcode != dns_opcode_update && !msg->tkey &&
++ rdtype == dns_rdatatype_key &&
++ msg->rdclass != dns_rdataclass_any &&
++ msg->rdclass != rdclass)
++ DO_FORMERR;
++
++ /*
+ * Special type handling for TSIG, OPT, and TKEY.
+ */
+ if (rdtype == dns_rdatatype_tsig) {
+@@ -1372,6 +1390,10 @@ getsection(isc_buffer_t *source, dns_message_t *msg, dns_decompress_t *dctx,
+ skip_name_search = ISC_TRUE;
+ skip_type_search = ISC_TRUE;
+ issigzero = ISC_TRUE;
++ } else {
++ if (msg->rdclass != dns_rdataclass_any &&
++ msg->rdclass != rdclass)
++ DO_FORMERR;
+ }
+ } else
+ covers = 0;
+@@ -1610,6 +1632,7 @@ dns_message_parse(dns_message_t *msg, isc_buffer_t *source,
+ msg->counts[DNS_SECTION_ADDITIONAL] = isc_buffer_getuint16(source);
+
+ msg->header_ok = 1;
++ msg->state = DNS_SECTION_QUESTION;
+
+ /*
+ * -1 means no EDNS.
+@@ -3550,3 +3573,15 @@ dns_message_buildopt(dns_message_t *message, dns_rdataset_t **rdatasetp,
+ dns_message_puttemprdatalist(message, &rdatalist);
+ return (result);
+ }
++
++void
++dns_message_setclass(dns_message_t *msg, dns_rdataclass_t rdclass) {
++
++ REQUIRE(DNS_MESSAGE_VALID(msg));
++ REQUIRE(msg->from_to_wire == DNS_MESSAGE_INTENTPARSE);
++ REQUIRE(msg->state == DNS_SECTION_ANY);
++ REQUIRE(msg->rdclass_set == 0);
++
++ msg->rdclass = rdclass;
++ msg->rdclass_set = 1;
++}
+diff --git a/lib/dns/resolver.c b/lib/dns/resolver.c
+index aa23b11..d220986 100644
+--- a/lib/dns/resolver.c
++++ b/lib/dns/resolver.c
+@@ -6964,6 +6964,8 @@ resquery_response(isc_task_t *task, isc_event_t *event) {
+ goto done;
+ }
+
++ dns_message_setclass(message, fctx->res->rdclass);
++
+ result = dns_message_parse(message, &devent->buffer, 0);
+ if (result != ISC_R_SUCCESS) {
+ switch (result) {
+@@ -7036,6 +7038,12 @@ resquery_response(isc_task_t *task, isc_event_t *event) {
+ */
+ log_packet(message, ISC_LOG_DEBUG(10), fctx->res->mctx);
+
++ if (message->rdclass != fctx->res->rdclass) {
++ resend = ISC_TRUE;
++ FCTXTRACE("bad class");
++ goto done;
++ }
++
+ /*
+ * Process receive opt record.
+ */
+diff --git a/lib/dns/xfrin.c b/lib/dns/xfrin.c
+index 9ad8960..938373a 100644
+--- a/lib/dns/xfrin.c
++++ b/lib/dns/xfrin.c
+@@ -1241,6 +1241,8 @@ xfrin_recv_done(isc_task_t *task, isc_event_t *ev) {
+ msg->tsigctx = xfr->tsigctx;
+ xfr->tsigctx = NULL;
+
++ dns_message_setclass(msg, xfr->rdclass);
++
+ if (xfr->nmsg > 0)
+ msg->tcp_continuation = 1;
+
