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Home » Security Advisories» NetBSD » Bridge memory disclosure

Bridge memory disclosure

The bridge ioctl calls did not zero out the stack memory used to temporarily store the results of the ioctl requests before copying them back to the requesting process. Thus portions of the kernel stack memory could be exposed to the calling process.

  • Vendor: NetBSD
  • Vendor ID: 2006-005
  • Date: March 28, 2006


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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

Abstract
========

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
# ./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
=========

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
ftp://ftp.NetBSD.org/pub/NetBSD/security/advisories/NetBSD-SA2006-005.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-SA2006-005.txt,v 1.8 2006/03/29 11:14:28 adrianp Exp $

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