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

Tonnerre LOMBARD <[email protected]> Wed, 27 Aug 2014 13:54:35 +0200
Newsgroups	gmane.os.netbsd.devel.security,gmane.os.netbsd.current
Message-ID	<[email protected]>
Salut,

Please ignore this advisory for now as it contains errors. It will be
re-published once these errors have been addressed.

I am deeply sorry for my failure to handle these advisories in an
appropriate way and to provide you with the level of service
you deserve.

On Wed, Aug 27, 2014 at 09:36:40AM +0000, NetBSD Security Officer wrote:
> 		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 1.1 2014/08/27 00:33:51 tonnerre Exp $
> 
> 

				Tonnerre
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