From f6ca6392adf7f5a94c804d8a8a1233d90170f490 Mon Sep 17 00:00:00 2001
From: Petr Mensik <pemensik@redhat.com>
Date: Fri, 15 May 2020 14:56:33 +0200
Subject: [PATCH] CVE-2020-8617

5390.	[security]	Replaying a TSIG BADTIME response as a request could
			trigger an assertion failure. (CVE-2020-8617)
			[GL #1703]
---
 lib/dns/tsig.c | 7 ++++---
 1 file changed, 4 insertions(+), 3 deletions(-)

diff --git a/lib/dns/tsig.c b/lib/dns/tsig.c
index c6f9d1b..aee8eb0 100644
--- a/lib/dns/tsig.c
+++ b/lib/dns/tsig.c
@@ -1431,8 +1431,9 @@ dns_tsig_verify(isc_buffer_t *source, dns_message_t *msg,
 			goto cleanup_context;
 		}
 		msg->verified_sig = 1;
-	} else if (tsig.error != dns_tsigerror_badsig &&
-		   tsig.error != dns_tsigerror_badkey) {
+	} else if (!response || (tsig.error != dns_tsigerror_badsig &&
+				 tsig.error != dns_tsigerror_badkey))
+	{
 		tsig_log(msg->tsigkey, 2, "signature was empty");
 		return (DNS_R_TSIGVERIFYFAILURE);
 	}
@@ -1488,7 +1489,7 @@ dns_tsig_verify(isc_buffer_t *source, dns_message_t *msg,
 		}
 	}
 
-	if (tsig.error != dns_rcode_noerror) {
+	if (response && tsig.error != dns_rcode_noerror) {
 		msg->tsigstatus = tsig.error;
 		if (tsig.error == dns_tsigerror_badtime)
 			ret = DNS_R_CLOCKSKEW;
-- 
2.21.1