From ed72b9434de22005814bf0f2ed0a9ba72506d30f Mon Sep 17 00:00:00 2001
From: Evan Hunt <each@isc.org>
Date: Mon, 25 Feb 2019 12:55:27 -0800
Subject: [PATCH] fix crash in query_respond_any() from all records being
 hidden

in query_respond_any(), the assumption had previously been made that it
was impossible to get past iterating the node with a return value of
ISC_R_NOMORE but not have found any records, unless we were searching
for RRSIG or SIG. however, it is possible for other types to exist but
be hidden, such as when the zone is transitioning from insecure to
secure and DNSSEC types are encountered, and this situation could
trigger an assertion.  removed the assertion and reorganized the code.

(cherry picked from commit 3e74c7e5ffc455051549b1199328c76ddc5c72cc)
---
 lib/ns/query.c | 91 ++++++++++++++++++++++++++++----------------------
 1 file changed, 52 insertions(+), 39 deletions(-)

diff --git a/lib/ns/query.c b/lib/ns/query.c
index b6c20fb185..477a11a5a7 100644
--- a/lib/ns/query.c
+++ b/lib/ns/query.c
@@ -6725,7 +6725,7 @@ query_addnoqnameproof(query_ctx_t *qctx) {
  */
 static isc_result_t
 query_respond_any(query_ctx_t *qctx) {
-	bool found = false;
+	bool found = false, hidden = false;
 	dns_rdatasetiter_t *rdsiter = NULL;
 	isc_result_t result;
 	dns_rdatatype_t onetype = 0; 	/* type to use for minimal-any */
@@ -6780,11 +6780,11 @@ query_respond_any(query_ctx_t *qctx) {
 		    dns_rdatatype_isdnssec(qctx->rdataset->type))
 		{
 			/*
-			 * The zone is transitioning from insecure
-			 * to secure. Hide the dnssec records from
-			 * ANY queries.
+			 * The zone may be transitioning from insecure
+			 * to secure. Hide DNSSEC records from ANY queries.
 			 */
 			dns_rdataset_disassociate(qctx->rdataset);
+			hidden = true;
 		} else if (qctx->view->minimal_any &&
 			   !TCP(qctx->client) && !WANTDNSSEC(qctx->client) &&
 			   qctx->qtype == dns_rdatatype_any &&
@@ -6806,7 +6806,8 @@ query_respond_any(query_ctx_t *qctx) {
 			    qctx->rdataset->type == qctx->qtype) &&
 			   qctx->rdataset->type != 0)
 		{
-			if (NOQNAME(qctx->rdataset) && WANTDNSSEC(qctx->client))
+			if (NOQNAME(qctx->rdataset) &&
+			    WANTDNSSEC(qctx->client))
 			{
 				qctx->noqname = qctx->rdataset;
 			} else {
@@ -6862,8 +6863,9 @@ query_respond_any(query_ctx_t *qctx) {
 			}
 
 			qctx->rdataset = ns_client_newrdataset(qctx->client);
-			if (qctx->rdataset == NULL)
+			if (qctx->rdataset == NULL) {
 				break;
+			}
 		} else {
 			/*
 			 * We're not interested in this rdataset.
@@ -6884,48 +6886,59 @@ query_respond_any(query_ctx_t *qctx) {
 	}
 
 	if (found) {
+		/*
+		 * Call hook if any answers were found.
+		 * Do this before releasing qctx->fname, in case
+		 * the hook function needs it.
+		 */
 		CALL_HOOK(NS_QUERY_RESPOND_ANY_FOUND, qctx);
-
-		if (qctx->fname != NULL) {
-			dns_message_puttempname(qctx->client->message,
-						&qctx->fname);
-		}
-
-		query_addauth(qctx);
-		return (ns_query_done(qctx));
 	}
 
-	/*
-	 * If we're here, no matching rdatasets were found.  If we were
-	 * searching for RRSIG/SIG, that may be okay, but otherwise
-	 * something's gone wrong.
-	 */
-	INSIST(qctx->qtype == dns_rdatatype_rrsig ||
-	       qctx->qtype == dns_rdatatype_sig);
-
 	if (qctx->fname != NULL) {
-		dns_message_puttempname(qctx->client->message,
-					&qctx->fname);
+		dns_message_puttempname(qctx->client->message, &qctx->fname);
 	}
 
-	if (!qctx->is_zone) {
-		qctx->authoritative = false;
-		qctx->client->attributes &= ~NS_CLIENTATTR_RA;
+	if (found) {
+		/*
+		 * At least one matching rdataset was found
+		 */
 		query_addauth(qctx);
-		return (ns_query_done(qctx));
+	} else if (qctx->qtype == dns_rdatatype_rrsig ||
+		   qctx->qtype == dns_rdatatype_sig)
+	{
+		/*
+		 * No matching rdatasets were found, but we got
+		 * here on a search for RRSIG/SIG, so that's okay.
+		 */
+		if (!qctx->is_zone) {
+			qctx->authoritative = false;
+			qctx->client->attributes &= ~NS_CLIENTATTR_RA;
+			query_addauth(qctx);
+			return (ns_query_done(qctx));
+		}
+
+		if (qctx->qtype == dns_rdatatype_rrsig &&
+		    dns_db_issecure(qctx->db))
+		{
+			char namebuf[DNS_NAME_FORMATSIZE];
+			dns_name_format(qctx->client->query.qname,
+					namebuf, sizeof(namebuf));
+			ns_client_log(qctx->client, DNS_LOGCATEGORY_DNSSEC,
+				      NS_LOGMODULE_QUERY, ISC_LOG_WARNING,
+				      "missing signature for %s", namebuf);
+		}
+
+		qctx->fname = ns_client_newname(qctx->client, qctx->dbuf, &b);
+		return (query_sign_nodata(qctx));
+	} else if (!hidden) {
+		/*
+		 * No matching rdatasets were found and nothing was
+		 * deliberately hidden: something must have gone wrong.
+		 */
+		QUERY_ERROR(qctx, DNS_R_SERVFAIL);
 	}
 
-	if (qctx->qtype == dns_rdatatype_rrsig && dns_db_issecure(qctx->db)) {
-		char namebuf[DNS_NAME_FORMATSIZE];
-		dns_name_format(qctx->client->query.qname,
-				namebuf, sizeof(namebuf));
-		ns_client_log(qctx->client, DNS_LOGCATEGORY_DNSSEC,
-			      NS_LOGMODULE_QUERY, ISC_LOG_WARNING,
-			      "missing signature for %s", namebuf);
-	}
-
-	qctx->fname = ns_client_newname(qctx->client, qctx->dbuf, &b);
-	return (query_sign_nodata(qctx));
+	return (ns_query_done(qctx));
 
  cleanup:
 	return (result);