NetBSD Security Advisory 2008-015: ICMPv6 Packet Too Big messages

[NetBSD Security-Officer <security-officer%netbsd.org@localhost>]

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                 NetBSD Security Advisory 2008-015
                 =================================

Topic:          ICMPv6 Packet Too Big messages

Version:        NetBSD-current:         affected
                NetBSD 4.0.*:           not affected
                NetBSD 4.0:             affected
                NetBSD 3.1.*:           affected
                NetBSD 3.1:             affected
                NetBSD 3.0.*:           affected
                NetBSD 3.0:             affected

Severity:       Denial of service

Fixed:          NetBSD-current:         October 03, 2008
                NetBSD-4-0 branch:      October 03, 2008
                        (4.0.1 includes the fix)
                NetBSD-4 branch:        October 03, 2008
                        (4.1 will include the fix)
                NetBSD-3-1 branch:      October 03, 2008
                        (3.1.2 will include the fix)
                NetBSD-3-0 branch:      October 03, 2008
                        (3.0.4 will include the fix)
                NetBSD-3 branch:        October 03, 2008
                        (3.2 will include the fix)


Abstract
========

An error may occur while processing ICMPv6 'Packet Too Big' (RFC 2463) 
messages which may result in a denial of service (system panic).

This vulnerability has been assigned CVE-2008-3530.


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

An error can occur when processing the proposed MTU of an ICMPv6 
'Packet Too Big' message.


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

Only kernels compiled with the following option are vulnerable to this issue:

        options INET6

As a temporary workaround recompile the kernel with the above option 
commented out.  The default NetBSD GENERIC kernels have this
option enabled.

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/netinet6/icmp6.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
=========

Matt Thomas for the fix and FreeBSD for initial analysis of the issue.


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

        2008-10-27      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-SA2008-015.txt.asc

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


Copyright 2008, The NetBSD Foundation, Inc.  All Rights Reserved.
Redistribution permitted only in full, unmodified form.

$NetBSD: NetBSD-SA2008-015.txt,v 1.4 2008/10/27 19:47:21 adrianp Exp $

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