From 9272c79b768240ff4e11f6b6dc9fa42cb6dd9177 Mon Sep 17 00:00:00 2001
From: mlelstv <mlelstv@NetBSD.org>
Date: Sat, 4 May 2024 13:33:18 +0000
Subject: [PATCH] Account for trailing NUL bytes when calculating userland
 buffer size.

---
 sys/kern/subr_iostat.c | 6 ++++--
 1 file changed, 4 insertions(+), 2 deletions(-)

diff --git a/sys/kern/subr_iostat.c b/sys/kern/subr_iostat.c
index 5db9c75f17b4..e50d89fb87bc 100644
--- a/sys/kern/subr_iostat.c
+++ b/sys/kern/subr_iostat.c
@@ -1,4 +1,4 @@
-/*	$NetBSD: subr_iostat.c,v 1.25 2019/05/22 08:47:02 hannken Exp $	*/
+/*	$NetBSD: subr_iostat.c,v 1.26 2024/05/04 13:33:18 mlelstv Exp $	*/
 /*	NetBSD: subr_disk.c,v 1.69 2005/05/29 22:24:15 christos Exp	*/
 
 /*-
@@ -68,7 +68,7 @@
  */
 
 #include <sys/cdefs.h>
-__KERNEL_RCSID(0, "$NetBSD: subr_iostat.c,v 1.25 2019/05/22 08:47:02 hannken Exp $");
+__KERNEL_RCSID(0, "$NetBSD: subr_iostat.c,v 1.26 2024/05/04 13:33:18 mlelstv Exp $");
 
 #include <sys/param.h>
 #include <sys/kernel.h>
@@ -370,6 +370,8 @@ iostati_getnames(int disk_only, char *oldp, size_t *oldlenp, const void *newp,
 			memset(bf, 0, sizeof(bf));
 			if (first) {
 				strncpy(bf, stats->io_name, sizeof(bf));
+				/* account for trailing NUL byte */
+				needed += 1;
 				first = 0;
 			} else {
 				bf[0] = ' ';