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Category:   OS (UNIX)  >   NetBSD Vendors:   NetBSD
NetBSD ptrace() and if_clone_list() Bugs Disclose Kernel Memory to Local Users
SecurityTracker Alert ID:  1017292
SecurityTracker URL:
CVE Reference:   CVE-2006-6656, CVE-2006-6657   (Links to External Site)
Updated:  May 27 2008
Original Entry Date:  Nov 28 2006
Impact:   Disclosure of authentication information, Disclosure of system information, Disclosure of user information
Fix Available:  Yes  Vendor Confirmed:  Yes  
Version(s): 2.0 - 3.1
Description:   A vulnerability was reported in NetBSD. A local user can read portions of kernel memory.

A local user can supply a specially crafted PT_LWPINFO request to the ptrace(2) function call to cause kernel memory to be leaked.

A local user can exploit the if_clone_list() function to cause the kernel to disclose up to IFNAMSIZ bytes of uninitialized stack memory.

Ben Hawkes of Suresec Pty. Ltd. reported this ptrace vulnerability. Christer Oberg of BitSec reported the if_clone_list() vulnerability.

Impact:   A local user can read portions of kernel memory.
Solution:   The vendor has issued a fixed kernel.

The NetBSD advisory is available at:

Vendor URL: (Links to External Site)
Cause:   Access control error

Message History:   None.

 Source Message Contents

Subject:  NetBSD Security Advisory 2006-025: Multiple information/memory leakage

Hash: SHA1

		 NetBSD Security Advisory 2006-025

Topic:		Multiple information/memory leakage issues

Version:	NetBSD-current:	source prior to October 27, 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:	Information/memory leakage.

Fixed:		NetBSD-current:		October 27, 2006
		NetBSD-3-0 branch:	October 27, 2006
		NetBSD-3 branch:	October 27, 2006
		NetBSD-2-1 branch:	November 19, 2006
		NetBSD-2-0 branch:	November 19, 2006
		NetBSD-2 branch:	November 19, 2006


There are multiple information/memory leakage issues present in the 
NetBSD kernel.

Technical Details

* ptrace memory/information leak
A userspace parameter passed to the ptrace(2) call involving a PT_LWPINFO 
request can result in a memory/information leak.

* if_clone_list() information leak
There is a minor kernel memory disclose in if_clone_list() where up to 
IFNAMSIZ bytes of uninitialized stack memory are copied out to userland.

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 sys/kern/sys_process.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

The ptrace memory/information leak was discovered and reported by
 Ben Hawkes of Suresec Pty. Ltd.
The if_clone_list() information leak was discovered and reported by
 Christer Oberg of BitSec.

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-SA2006-025.txt,v 1.3 2006/11/27 20:14:45 adrianp Exp $

Version: GnuPG v1.4.5 (NetBSD)



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