From 6fc38d1c75ce5a6172267e6ca162c4fdc09657ad Mon Sep 17 00:00:00 2001 From: Petr Mensik Date: Tue, 27 Apr 2021 10:56:12 +0200 Subject: [PATCH 2/2] CVE-2021-25215 5616. [security] named crashed when a DNAME record placed in the ANSWER section during DNAME chasing turned out to be the final answer to a client query. (CVE-2021-25215) [GL #2540] --- bin/named/query.c | 13 ++++++++++--- 1 file changed, 10 insertions(+), 3 deletions(-) diff --git a/bin/named/query.c b/bin/named/query.c index a95f5ad..11a888e 100644 --- a/bin/named/query.c +++ b/bin/named/query.c @@ -9301,10 +9301,17 @@ query_find(ns_client_t *client, dns_fetchevent_t *event, dns_rdatatype_t qtype) if (noqname != NULL) query_addnoqnameproof(client, noqname); /* - * We shouldn't ever fail to add 'rdataset' - * because it's already in the answer. + * 'rdataset' will only be non-NULL here if the ANSWER section + * of the message to be sent to the client already contains an + * RRset with the same owner name and the same type as + * 'rdataset'. This should never happen, with one exception: + * when chasing DNAME records, one of the DNAME records placed + * in the ANSWER section may turn out to be the final answer to + * the client's query, but we have no way of knowing that until + * now. In such a case, 'rdataset' will be freed later, so we + * do not need to free it here. */ - INSIST(rdataset == NULL); + INSIST(rdataset == NULL || qtype == dns_rdatatype_dname); } addauth: -- 2.26.3