[master] remove unnecessary INSIST

4578.	[security]	Some chaining (CNAME or DNAME) responses to upstream
			queries could trigger assertion failures.
			(CVE-2017-3137) [RT #44734]

diff --git a/CHANGES b/CHANGES
index 998abefbd121654b9146233304f298217d712f26..edc11d38f36aff689181097a3bd69c49c3a3d0bc 100644 (file)
--- a/CHANGES
+++ b/CHANGES
@@ -1,3 +1,7 @@
+4578.  [security]      Some chaining (CNAME or DNAME) responses to upstream
+                       queries could trigger assertion failures.
+                       (CVE-2017-3137) [RT #44734]
+
 4577.  [func]          Make qtype of resolver fuzzing packet configurable
                        via command line. [RT #43540]
 

diff --git a/doc/arm/notes.xml b/doc/arm/notes.xml
index 57f563844c41f17d23e895c57448bd75545f3d20..84b70b195ecd2e948a94a6ece5ed8addfc7e1791 100644 (file)
--- a/doc/arm/notes.xml
+++ b/doc/arm/notes.xml
@@ -65,11 +65,18 @@
 
   <section xml:id="relnotes_security"><info><title>Security Fixes</title></info>
     <itemizedlist>
+      <listitem>
+       <para>
+         Some chaining (i.e., type CNAME or DNAME) responses to upstream
+         queries could trigger assertion failures. This flaw is disclosed
+         in CVE-2017-3137. [RT #44734]
+       </para>
+      </listitem>
       <listitem>
        <para>
          <command>dns64</command> with <command>break-dnssec yes;</command>
          can result in an assertion failure. This flaw is disclosed in
-         CVE-2017-3136.[RT #44653]
+         CVE-2017-3136. [RT #44653]
        </para>
       </listitem>
       <listitem>

diff --git a/lib/dns/resolver.c b/lib/dns/resolver.c
index 9261c597e1c7a6dd2c042a7ad5b2a4f5c61b9edf..52f7c5c2c4ecfcb8021af1569c006d3088b7c3e2 100644 (file)
--- a/lib/dns/resolver.c
+++ b/lib/dns/resolver.c
@@ -7034,15 +7034,15 @@ answer_response(fetchctx_t *fctx) {
                                        rdataset->attributes |=
                                                DNS_RDATASETATTR_CACHE;
                                        rdataset->trust = dns_trust_answer;
-                                       if (chaining == 0) {
+                                       if (external) {
                                                /*
-                                                * This data is "the" answer
-                                                * to our question only if
-                                                * we're not chaining (i.e.
-                                                * if we haven't followed
-                                                * a CNAME or DNAME).
+                                                * This data is outside of
+                                                * our query domain, and
+                                                * may not be cached.
                                                 */
-                                               INSIST(!external);
+                                               rdataset->attributes |=
+                                                   DNS_RDATASETATTR_EXTERNAL;
+                                       } else if (chaining == 0) {
                                                /*
                                                 * Don't use found_cname here
                                                 * as we have just set it
@@ -7064,14 +7064,6 @@ answer_response(fetchctx_t *fctx) {
                                                if (aa)
                                                        rdataset->trust =
                                                          dns_trust_authanswer;
-                                       } else if (external) {
-                                               /*
-                                                * This data is outside of
-                                                * our query domain, and
-                                                * may not be cached.
-                                                */
-                                               rdataset->attributes |=
-                                                   DNS_RDATASETATTR_EXTERNAL;
                                        }
 
                                        /*
@@ -7246,15 +7238,12 @@ answer_response(fetchctx_t *fctx) {
                                 * If we are not chaining or the first CNAME
                                 * is a synthesised CNAME before the DNAME.
                                 */
-                               if ((chaining == 0) ||
-                                   (chaining == 1U && synthcname))
+                               if (external) {
+                                       rdataset->attributes |=
+                                           DNS_RDATASETATTR_EXTERNAL;
+                               } else if ((chaining == 0) ||
+                                          (chaining == 1U && synthcname))
                                {
-                                       /*
-                                        * This data is "the" answer to
-                                        * our question only if we're
-                                        * not chaining.
-                                        */
-                                       INSIST(!external);
                                        if (aflag == DNS_RDATASETATTR_ANSWER) {
                                                have_answer = ISC_TRUE;
                                                found_dname = ISC_TRUE;
@@ -7271,9 +7260,6 @@ answer_response(fetchctx_t *fctx) {
                                        if (aa)
                                                rdataset->trust =
                                                  dns_trust_authanswer;
-                               } else if (external) {
-                                       rdataset->attributes |=
-                                           DNS_RDATASETATTR_EXTERNAL;
                                }
                        }