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             AUSCERT External Security Bulletin Redistribution

                         ESB-2006.0870 -- [NetBSD]
                     Multiple denial of service issues
                             28 November 2006


        AusCERT Security Bulletin Summary

Product:              kernel
Publisher:            NetBSD
Operating System:     NetBSD
Impact:               Denial of Service
Access:               Existing Account

Original Bulletin:   

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Hash: SHA1

		 NetBSD Security Advisory 2006-026

Topic:		Multiple denial of service issues

Version:	NetBSD-current:	source prior to October 23, 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:	Denial of service issues ranging from resource leaks to
		kernel panics.

Fixed:		NetBSD-current:		October 23, 2006
		NetBSD-3-0 branch:	October 24, 2006
		NetBSD-3 branch:	October 24, 2006
		NetBSD-2-1 branch:	October 29, 2006
		NetBSD-2-0 branch:	October 29, 2006
		NetBSD-2 branch:	October 29, 2006


There are multiple denial of service issues that can result in resource
leaks or kernel panics.

Technical Details

* Dangling socket could exhaust local system resources
If a user supplies a bad 'name' or 'namelen' parameter to accept(2) this
could leave a dangling socket.  If bad parameters were supplied and a 
copyout(9) failed, the 'file' structure was cleaned up, but not the 
associated socket.  This could leave sockets in the CLOSE_WAIT state that 
could never be closed.

* sendmsg(2) panic
On 64-bit architectures (e.g. amd64, sparc64, and alpha) sendmsg(2) 
can cause a kernel panic, due to insufficient checks of the 'msg_controllen'
parameter in sendit().

* mount_procfs panic (with -o linux)
Trying to read '/emul/linux/proc/0/stat' on a procfs mounted with the 'linux'
option results in a kernel panic.  The process in question has to no parent
process, resulting in a NULL dereference due to insufficient checks.

Solutions and Workarounds

* The sendmsg(2) panic only affects 64-bit systems.

* By default, procfs is not mounted with the 'linux' option, however it is
  often enabled when using Linux emulation.

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/uipc_syscalls.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:


Thanks To

The dangling socket issue was discovered and fixed by Sean Boudreau.
The sendmsg(2) panic was discovered and reported by Ryo Shimizu.
The mount_procfs panic was discovered and reported Nicolas Joly.

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
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-SA2006-026.txt,v 1.3 2006/11/27 20:14:45 adrianp Exp $

Version: GnuPG v1.4.5 (NetBSD)


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