NetBSD Security Advisory 2019-002: Unprivileged kernel memory overwrite in mq_send(3)

[NetBSD Security-Officer <security-officer%netbsd.org@localhost>]

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		 NetBSD Security Advisory 2019-002
		 =================================

Topic:		Unprivileged kernel memory overwrite in mq_send(3)

Version:	NetBSD-current:		affected prior to April 16, 2019
		NetBSD 8.0:		affected
		NetBSD 7.2:		affected
		NetBSD 7.1.2:		affected
		NetBSD 7.0.2:		affected

Severity:	Local user may overwrite kernel memory


Fixed:		NetBSD-current:		April 16, 2019
		NetBSD-8 branch:	April 16, 2019
		NetBSD-7 branch:	April 16, 2019
		NetBSD-7-1 branch:	April 16, 2019
		NetBSD-7-0 branch:	April 16, 2019

Please note that NetBSD releases prior to 7.1 are no longer supported.
It is recommended that all users upgrade to a supported release.

Abstract
========

An unprivileged user can overwrite parts of kernel memory via an unprivileged
mq_send(3) system call.

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

Insufficient argument validation in the mq_send(3) system call could cause
a copyin(9) operation of too much data, overrunning the kernel target
memory.


Solutions and Workarounds
=========================

Update the kernel to a fixed version and reboot.

To apply a fixed version from a releng build, fetch a fitting kern-GENERIC.tgz
from nyftp.netbsd.org and extract the fixed binaries:

cd /var/tmp
ftp https://nycdn.NetBSD.org/pub/NetBSD-daily/REL/latest/ARCH/binary/sets/kern-GENERIC.tgz
cd /
tar xzpf /var/tmp/kern-GENERIC.tgz

with the following replacements:
REL   = the release version you are using
ARCH  = your system's architecture


The following instructions describe how to upgrade your kernel by
updating your source tree and rebuilding and installing a new version.

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/path/to/file.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/docs/guide/en/chap-kernel.html

Thanks To
=========

Andy Nguyen for discovering and reporting the issue.

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-SA2019-002.txt.asc

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


Copyright 2019, The NetBSD Foundation, Inc.  All Rights Reserved.
Redistribution permitted only in full, unmodified form.

$NetBSD: NetBSD-SA2019-002.txt.asc,v 1.1 2019/05/03 01:33:11 christos Exp $
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