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