Subject: NetBSD Security Advisory 2006-005: bridge memory disclosure
To: None <>
From: NetBSD Security-Officer <>
List: tech-security
Date: 03/30/2006 02:50:09
Hash: SHA1

		 NetBSD Security Advisory 2006-005

Topic:		bridge memory disclosure

Version:	NetBSD-current:	source prior to January 17, 2006
		NetBSD 3.0:	affected
		NetBSD 2.1:	affected
		NetBSD 2.0.*:	affected
		NetBSD 2.0:	affected
		NetBSD 1.6.*:	affected
		NetBSD 1.6:	affected

Severity:	Kernel sensitive information can be disclosed

Fixed:		NetBSD-current:		January 17, 2006
		NetBSD-3-0 branch:	February 12, 2006
						(3.0.1 will include the fix)
		NetBSD-3   branch:	February 12, 2006
		NetBSD-2-1 branch:	February 12, 2006
						(2.1.1 will include the fix)
		NetBSD-2-0 branch:	February 12, 2006
						(2.0.4 will include the fix)
		NetBSD-2   branch:	February 12, 2006


An information disclosure issue exists in if_bridge(4) code.

Technical Details

The bridge(4) ioctl(2) calls did not zero out the stack memory used
to temporarily store the results of the ioctl(2) requests before
copying them back to the requesting process. Thus portions of the
kernel stack memory could be exposed to the calling process. The
impact of this is minor since:

	1. the number of bytes exposed is small
	2. the location and therefore the contents cannot be controlled 
	   by the calling process and 
	3. the buffer is partially overwritten by the results

Solutions and Workarounds

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/net/if_bridge.c
	# ./ 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

Xin LI for notification and the initial fixes.
Christos Zoulas for implementing the fixes.

Revision History

	2006-03-29	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-SA2006-005.txt,v 1.8 2006/03/29 11:14:28 adrianp Exp $

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