===================================================================
RCS file: /cvsrepo/anoncvs/cvs/src/usr.bin/tmux/cmd-new-session.c,v
retrieving revision 1.136
retrieving revision 1.137
diff -u -r1.136 -r1.137
--- src/usr.bin/tmux/cmd-new-session.c	2021/06/10 07:24:45	1.136
+++ src/usr.bin/tmux/cmd-new-session.c	2021/07/06 08:18:38	1.137
@@ -1,4 +1,4 @@
-/* $OpenBSD: cmd-new-session.c,v 1.136 2021/06/10 07:24:45 nicm Exp $ */
+/* $OpenBSD: cmd-new-session.c,v 1.137 2021/07/06 08:18:38 nicm Exp $ */
 
 /*
  * Copyright (c) 2007 Nicholas Marriott <nicholas.marriott@gmail.com>
@@ -102,6 +102,11 @@
 	if (tmp != NULL) {
 		name = format_single(item, tmp, c, NULL, NULL, NULL);
 		newname = session_check_name(name);
+		if (newname == NULL) {
+			cmdq_error(item, "invalid session: %s", name);
+			free(name);
+			return (CMD_RETURN_ERROR);
+		}
 		free(name);
 	}
 	if (args_has(args, 'A')) {
@@ -134,8 +139,14 @@
 			prefix = xstrdup(sg->name);
 		else if (groupwith != NULL)
 			prefix = xstrdup(groupwith->name);
-		else
+		else {
 			prefix = session_check_name(group);
+			if (prefix == NULL) {
+				cmdq_error(item, "invalid session group: %s",
+				    group);
+				goto fail;
+			}
+		}
 	}
 
 	/* Set -d if no client. */