--- /n/sources/plan9/sys/src/9/port/devmnt.c	Sun Mar 24 17:05:55 2024
+++ /sys/src/9/port/devmnt.c	Tue Sep 22 00:00:00 2026
@@ -878,6 +878,10 @@
 		hlen = len;
 		break;
 	}
+	if(len < hlen){
+		qdiscard(m->q, qlen(m->q));
+		return -1;
+	}
 	nb = pullupqueue(m->q, hlen);
 
 	if(convM2S(nb->rp, len, &r->reply) <= 0){