===================================================================
RCS file: /cvsrepo/anoncvs/cvs/src/usr.bin/doas/doas.c,v
retrieving revision 1.81
retrieving revision 1.82
diff -u -r1.81 -r1.82
--- src/usr.bin/doas/doas.c	2019/09/14 17:47:00	1.81
+++ src/usr.bin/doas/doas.c	2019/10/18 17:15:45	1.82
@@ -1,4 +1,4 @@
-/* $OpenBSD: doas.c,v 1.81 2019/09/14 17:47:00 semarie Exp $ */
+/* $OpenBSD: doas.c,v 1.82 2019/10/18 17:15:45 tedu Exp $ */
 /*
  * Copyright (c) 2015 Ted Unangst <tedu@openbsd.org>
  *
@@ -52,9 +52,11 @@
 
 	if ((pw = getpwnam(s)) != NULL) {
 		*uid = pw->pw_uid;
+		if (*uid == UID_MAX)
+			return -1;
 		return 0;
 	}
-	*uid = strtonum(s, 0, UID_MAX, &errstr);
+	*uid = strtonum(s, 0, UID_MAX - 1, &errstr);
 	if (errstr)
 		return -1;
 	return 0;
@@ -80,9 +82,11 @@
 
 	if ((gr = getgrnam(s)) != NULL) {
 		*gid = gr->gr_gid;
+		if (*gid == GID_MAX)
+			return -1;
 		return 0;
 	}
-	*gid = strtonum(s, 0, GID_MAX, &errstr);
+	*gid = strtonum(s, 0, GID_MAX - 1, &errstr);
 	if (errstr)
 		return -1;
 	return 0;