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AUSCERT External Security Bulletin Redistribution
ESB-2017.0192
Memory leak in the connect system call
23 January 2017
===========================================================================
AusCERT Security Bulletin Summary
---------------------------------
Product: kernel
Publisher: NetBSD
Operating System: NetBSD
Impact/Access: Denial of Service -- Existing Account
Resolution: Patch/Upgrade
Original Bulletin:
http://ftp.netbsd.org/pub/NetBSD/security/advisories/NetBSD-SA2017-001.txt.asc
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NetBSD Security Advisory 2017-001
=================================
Topic: Memory leak in the connect system call
Version: NetBSD-current: source prior to Sun, Oct 31st 2016
NetBSD 7.0 - 7.0.2: affected
NetBSD 6.1 - 6.1.4: affected
NetBSD 6.0 - 6.0.5: affected
Severity: Local DoS
Fixed: NetBSD-current: Sun, Oct 31st 2016
NetBSD-7-0 branch: Tue, Nov 1st 2016
NetBSD-7 branch: Tue, Nov 1st 2016
NetBSD-6-0 branch: Fri, Nov 11th 2016
NetBSD-6-1 branch: Fri, Nov 11th 2016
NetBSD-6 branch: Fri, Nov 11th 2016
Teeny versions released later than the fix date will contain the fix.
Please note that NetBSD releases prior to 6.0 are no longer supported.
It is recommended that all users upgrade to a supported release.
Abstract
========
A memory leak in the kernel could allow a local user to use up kernel
memory via repeated calls to the connect system call, and thus to
freeze - or eventually panic - the system.
Technical Details
=================
When calling the connect system call on a particular file descriptor with
specific arguments, a kernel buffer allocated to temporarily hold a path
buffer was not freed. Performing such a call in a loop would cause the
kernel to run out of memory and eventually panic.
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-7 netbsd-7-0 netbsd-6 netbsd-6-1 netbsd-6-0
---- ---- -------- ---------- -------- ---------- ----------
sys/kern/uipc_usrreq.c
1.181 1.169.2.4 1.169.2.3.2.1 1.136.8.4 1.136.8.3.2.1 1.136.8.2.2.1
To update from CVS, re-build, and re-install the kernel:
# cd src
# cvs update -d -P -r VERSION sys/kern/uipc_usrreq.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
=========
The Mootja Analysis Engine for detecting the issue, Maxime Villard for
developing it and writing a fix.
Revision History
================
2017-01-21 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-SA2017-001.txt.asc
Information about NetBSD and NetBSD security can be found at
http://www.NetBSD.org/ and http://www.NetBSD.org/Security/ .
Copyright 2017, The NetBSD Foundation, Inc. All Rights Reserved.
Redistribution permitted only in full, unmodified form.
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