[src/trunk]: src/sys/kern Fix buffer overflow, which can lead to severe infor...

[maxv <maxv%NetBSD.org@localhost>]

details:   https://anonhg.NetBSD.org/src/rev/dee3e073449f
branches:  trunk
changeset: 445768:dee3e073449f
user:      maxv <maxv%NetBSD.org@localhost>
date:      Mon Nov 12 06:55:03 2018 +0000

description:
Fix buffer overflow, which can lead to severe information leak. Detected
by kASan.

diffstat:

 sys/kern/kern_proc.c |  7 ++++---
 1 files changed, 4 insertions(+), 3 deletions(-)

diffs (28 lines):

diff -r 431eebec896a -r dee3e073449f sys/kern/kern_proc.c
--- a/sys/kern/kern_proc.c      Mon Nov 12 06:53:43 2018 +0000
+++ b/sys/kern/kern_proc.c      Mon Nov 12 06:55:03 2018 +0000
@@ -1,4 +1,4 @@
-/*     $NetBSD: kern_proc.c,v 1.218 2018/10/05 22:12:38 christos Exp $ */
+/*     $NetBSD: kern_proc.c,v 1.219 2018/11/12 06:55:03 maxv Exp $     */
 
 /*-
  * Copyright (c) 1999, 2006, 2007, 2008 The NetBSD Foundation, Inc.
@@ -62,7 +62,7 @@
  */
 
 #include <sys/cdefs.h>
-__KERNEL_RCSID(0, "$NetBSD: kern_proc.c,v 1.218 2018/10/05 22:12:38 christos Exp $");
+__KERNEL_RCSID(0, "$NetBSD: kern_proc.c,v 1.219 2018/11/12 06:55:03 maxv Exp $");
 
 #ifdef _KERNEL_OPT
 #include "opt_kstack.h"
@@ -2459,7 +2459,8 @@
 
        size_t len = strlen(p->p_path) + 1;
        if (oldp != NULL) {
-               error = sysctl_copyout(l, p->p_path, oldp, *oldlenp);
+               size_t copylen = uimin(len, *oldlenp);
+               error = sysctl_copyout(l, p->p_path, oldp, copylen);
                if (error == 0 && *oldlenp < len)
                        error = ENOSPC;
        }