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 ab02d32e0998f2703372d7d0faae886c40a63ab0..f70dae99846f19175c8e43b7507d4a06acf77f08 100644 (file)
--- a/lib/dns/rdataset.c
+++ b/lib/dns/rdataset.c
@@ -337,6 +337,7 @@ 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);