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     NetBSD Security Advisory 2006-001
     =================================

Topic:    Kernfs kernel memory disclosure

Version:  NetBSD-current:  source prior to November 23, 2005
    NetBSD 3.0:  not affected
    NetBSD 2.1:  affected
    NetBSD 2.0.3:  affected
    NetBSD 2.0:  affected
    NetBSD 1.6:  affected

Severity:  kernel sensitive information can be disclosed

Fixed:    NetBSD-current:    November 23, 2005
    NetBSD-3   branch:  November 24, 2005
    NetBSD-2.1 branch:  November 29, 2005
    NetBSD-2.0 branch:  November 29, 2005
    NetBSD-2   branch:  November 29, 2005
    NetBSD-1.6 branch:  November 29, 2005

Abstract
========

The kernfs filesystem does not validate file offsets properly and
a userlevel non-privileged process can read arbitrary kernel memory
locations.

Technical Details
=================

The lseek(2) system call for the kernfs file system has insufficient
bounds checking, allowing arbitrary memory locations to be read.

Solutions and Workarounds
=========================

A workaround for the issue is to not mount the kernfs file system.

For all NetBSD versions, you need to obtain fixed kernel sources,
rebuild and install the new kernel, and reboot the system.

The fixed source may be obtained from the NetBSD CVS repository.

The following instructions briefly summarise how to upgrade your
kernel.  In these instructions, replace:

  ARCH     with your architecture (from uname -m), and 
  KERNCONF with the name of your kernel configuration file.

To update from CVS, re-build, and re-install the kernel:

        # cd src
        # cvs update -d -P sys/miscfs/kernfs/kernfs_vnops.c
  # ./build.sh kernel=KERNCONF
  # mv /netbsd /netbsd.old
  # cp sys/arch/ARCH/compile/obj/KERNCONF/netbsd /netbsd
  # shutdown -r now

For more information on how to do this, see:

   http://www.NetBSD.org/guide/en/chap-kernel.html


Thanks To
=========

Ejovi Nuwere from SecurityLab for reporting the bug and Christos Zoulas
for the fix.


Revision History
================

  2006-01-09  Initial release


More Information
================

Advisories may be updated as new information becomes available.
The most recent version of this advisory (PGP signed) can be found at 
  ftp://ftp.NetBSD.org/pub/NetBSD/security/advisories/NetBSD-SA2006-001.txt.asc

Information about NetBSD and NetBSD security can be found at
http://www.NetBSD.org/ and http://www.NetBSD.org/Security/.


Copyright 2006, The NetBSD Foundation, Inc.  All Rights Reserved.
Redistribution permitted only in full, unmodified form.

$NetBSD: NetBSD-SA2006-001.txt,v 1.5 2006/01/09 14:48:35 gendalia Exp $

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