https://gitlab.isc.org/isc-projects/bind9/-/commit/b6670787d25743ddf39dfe8e615828efc928f50d
https://gitlab.isc.org/isc-projects/bind9/-/issues/3351
https://bugs.gentoo.org/847295

From: Evan Hunt <each@isc.org>
Date: Fri, 13 May 2022 19:59:58 -0700
Subject: [PATCH] prevent a possible buffer overflow in configuration check

corrected code that could have allowed a buffer overfow while
parsing named.conf.

(cherry picked from commit 921043b54161c7a3e6dc4036b038ca4dbc5fe472)
--- a/lib/bind9/check.c
+++ b/lib/bind9/check.c
@@ -2500,8 +2500,8 @@ check_zoneconf(const cfg_obj_t *zconfig, const cfg_obj_t *voptions,
 		} else if (dns_name_isula(zname)) {
 			ula = true;
 		}
-		tmp += strlen(tmp);
 		len -= strlen(tmp);
+		tmp += strlen(tmp);
 		(void)snprintf(tmp, len, "%u/%s", zclass,
 			       (ztype == CFG_ZONE_INVIEW) ? target
 			       : (viewname != NULL)	  ? viewname
@@ -3247,8 +3247,8 @@ check_zoneconf(const cfg_obj_t *zconfig, const cfg_obj_t *voptions,
 		char *tmp = keydirbuf;
 		size_t len = sizeof(keydirbuf);
 		dns_name_format(zname, keydirbuf, sizeof(keydirbuf));
-		tmp += strlen(tmp);
 		len -= strlen(tmp);
+		tmp += strlen(tmp);
 		(void)snprintf(tmp, len, "/%s", (dir == NULL) ? "(null)" : dir);
 		tresult = keydirexist(zconfig, (const char *)keydirbuf,
 				      kaspname, keydirs, logctx, mctx);
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