Subject: NetBSD Security Advisory 2006-024: systrace(4) integer overflow
To: None <>
From: NetBSD Security-Officer <>
List: current-users
Date: 11/27/2006 22:58:56
Hash: SHA1

		 NetBSD Security Advisory 2006-024

Topic:		systrace(4) integer overflow

Version:	NetBSD-current:	source prior to October 6, 2006
		NetBSD 3.1:		not affected
		NetBSD 3.0.2:		not affected
		NetBSD 3.0.1:		affected
		NetBSD 3.0:		affected
		NetBSD 2.1:		affected
		NetBSD 2.0.*:		affected
		NetBSD 2.0:		affected

Severity:	Local privilege escalation and denial of service

Fixed:		NetBSD-current:		October 6, 2006
		NetBSD-3-0 branch:	October 16, 2006
		NetBSD-3 branch:	October 16, 2006
		NetBSD-2-1 branch:	November 19, 2006
		NetBSD-2-0 branch:	November 19, 2006
		NetBSD-2 branch:	November 19, 2006


An integer overflow in systrace(4) can potentially lead to a local
denial of service and/or privilege escalation.

This vulnerability has been assigned CVE reference CVE-2006-5218.

Technical Details

A check for integer overflow is missing in the kernel component of systrace.
The problem is located in the "systrace_preprepl()" function.
The vulnerability can be triggered by passing a large (or negative) integer
value to a systrace ioctl().

Solutions and Workarounds

A possible solution is to disable systrace by commenting out the 
"options SYSTRACE" line in your kernel configuration file.  You
will need to re-compile and install the new kernel for the change
to become effective on reboot.

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 sys/sys/systrace.h \
	# ./ 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:

Thanks To

Chris Evans is credited with the discovery of this issue.

Revision History

	2006-11-27	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

Information about NetBSD and NetBSD security can be found at and

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

$NetBSD: NetBSD-SA2006-024.txt,v 1.3 2006/11/27 20:14:45 adrianp Exp $

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