add a REQUIRE to catch the NULL pointer dereference that triggered CVE-2017-3135

(cherry picked from commit 1d8995d226d8bca96b8ba286316018be4b7835f2)

diff --git a/lib/dns/rdataset.c b/lib/dns/rdataset.c
index 25f7e6db4f11af6a4b7743e9866c4b4b4597249a..803d08b1009de265f62a692220cca4881034bf87 100644 (file)
--- a/lib/dns/rdataset.c
+++ b/lib/dns/rdataset.c
@@ -334,6 +334,7 @@ towiresorted(dns_rdataset_t *rdataset, const dns_name_t *owner_name,
         */
 
        REQUIRE(DNS_RDATASET_VALID(rdataset));
+       REQUIRE(rdataset->methods != NULL);
        REQUIRE(countp != NULL);
        REQUIRE((order == NULL) == (order_arg == NULL));
        REQUIRE(cctx != NULL && cctx->mctx != NULL);