diff --git a/sys/netgraph/netgraph/ng_base.c b/sys/netgraph/netgraph/ng_base.c
--- a/sys/netgraph/netgraph/ng_base.c
+++ b/sys/netgraph/netgraph/ng_base.c
@@ -570,7 +570,7 @@
 		if (name[i] == '\0' || name[i] == '.' || name[i] == ':')
 			break;
 	}
-	if (i == 0 || name[i] != '\0') {
+	if (i == 0 || i >= NG_NODESIZ || name[i] != '\0') {
 		TRAP_ERROR;
 		return (EINVAL);
 	}