BSDSec

deadsimple BSD Security Advisories and Announcements

NetBSD Security Advisory 2014-011: User-controlled memory allocation in the modctl system call

-----BEGIN PGP SIGNED MESSAGE-----
Hash: SHA1

		NetBSD Security Advisory 2014-011
		=================================

Topic:		User-controlled memory allocation in the modctl system call


Version:	NetBSD-current:		source prior to Thu, Jul 10th 2014
		NetBSD 6.1 - 6.1.4:	affected
		NetBSD 6.0 - 6.0.5:	affected
		NetBSD 5.1 - 5.1.4:	affected
		NetBSD 5.2 - 5.2.2:	affected

Severity:	Local DoS

Fixed:		NetBSD-current:		Thu, Jul 10th 2014
		NetBSD-6-1 branch:	Mon, Jul 14th 2014
		NetBSD-6-0 branch:	Mon, Jul 14th 2014
		NetBSD-6 branch:	Mon, Jul 14th 2014
		NetBSD-5.2 branch:	Mon, Jul 14th 2014
		NetBSD-5.1 branch:	Mon, Jul 14th 2014
		NetBSD-5 branch:	Mon, Jul 14th 2014

Teeny versions released later than the fix date will contain the fix.

Please note that NetBSD releases prior to 5.1 are no longer supported.
It is recommended that all users upgrade to a supported release.


Abstract
========

Due to missing input validation checks, a local (un)privileged user
could cause the kernel to perform a zero-sized or unbounded memory
allocation, resulting in a crash.


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

The modctl system call takes as second argument a buffer which is
represented as a structure when loading a kernel module. This structure
indicates special information on how to load a module, including a
string pointer and the length of the string pointed to. A kernel buffer
of the same size is allocated, but no check was performed to ensure the
size is neither too low nor too high, thus allowing a local user to
crash the system.


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),
  KERNCONF with the name of your kernel configuration file and
  VERSION  with the file version below

File versions containing the fixes:

 FILE  HEAD  netbsd-6  netbsd-6-1  netbsd-6-0  netbsd-5  netbsd-5-2  netbsd-5-1
 ----  ----  --------  ----------  ----------  --------  ----------  ----------
 sys/kern/sys_module.c
       1.15  1.13.8.1  1.13.14.1   1.13.12.1   1.8.4.2   1.8.4.1.6.1 1.8.4.1.2.1

To update from CVS, re-build, and re-install the kernel:

	# cd src
	# cvs update -d -P -r VERSION sys/kern/sys_module.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
=========

Thanks to Maxime Villard, who found the issue and provided a fix.


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

	2014-08-27	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 
  http://ftp.NetBSD.org/pub/NetBSD/security/advisories/NetBSD-SA2014-011.txt.asc

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


Copyright 2014, The NetBSD Foundation, Inc.  All Rights Reserved.
Redistribution permitted only in full, unmodified form.

$NetBSD: NetBSD-SA2014-011.txt,v 1.3 2014/08/30 07:00:29 maxv Exp $

-----BEGIN PGP SIGNATURE-----
Version: GnuPG v1

iQIcBAEBAgAGBQJUDhArAAoJEAZJc6xMSnBuHygP/juhVWWrWtPQQzGbCE9Jksqn
SEvyoNvSNtjUdp+1gSqsZe8x7xYg2DNaGqvVORYVm9fpP7Kn5//7ub1GaI1PNbVP
+7Vn4jtNs+jeMrhLo5yAhSilb3DorRTIzvhkyNmU1P9zwAaHuV1PNIjBDkmXN3mL
JbxSf6/X5xcSl3gCmE6UE+sQ45bvLVMnKEv0cuNO6CLxf0YKuJCTyp6Wh55bzjPq
Vw64j2WLB1mU/EVhF7GHHQ1QhnpoGnZ1UwYxVlqeH1dR+9RPYj1Kjh784kDOVN6K
j2yulxDLrz07we1IEqmWW7slLK3qWRARLJgEDd6NEiB677GImuYDRYtEdUFI/wSV
NcoDXCAoFeFuvZUqjFCbKmcC0bBrfoBbRLvuLyogAZ51iAbUpJpUwn6BamftcRo/
2qKwdNDbaqXvXTGeaF98DKR+RsiG69Z1P9l2OmzSV29Jn2WC9Tz5Dbh2Dd5fsHQV
t0tCCApbI2UiLu4OFi9DhxhraiO0gBlPaTjtnc1fnyLapjw4lZFo2q6xnHmrtj4l
CYTQuVghHly4yeDHPMISpipmgzx9Z/lQadUejbv65j1Id4PLMPSezNKzSZJRy+D2
I7cv0rn0nT2PVDNRbmsVpZCiJjILKI4GXcwpXfKEma/dEeqJjuClwe5P/zZffYOx
4y8sbEeOXHwBqmF76e+d
=wcom
-----END PGP SIGNATURE-----