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The U.S. Department of Energy
Computer Incident Advisory Capability
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INFORMATION BULLETIN

Linux Kernel Vulnerable to DoS via ipv6_getsockopt_sticky() Function
[US-CERT Vulnerability Note VU#920689]

March 14, 2007 19:00 GMT Number R-177
[REVISED 1 May 2007]
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PROBLEM: The Linux Kernel contains a vulnerability that may allow a
remote attacker to create a denial-of-service condition.
PLATFORM: Linux Kernel version 2.6.20.1
RHEL Desktop Workstation (v. 5 client)
Red Hat Enterprise Linux (v. 5 server)
Red Hat Enterprise Linux Desktop (v. 5 client)
DAMAGE: May allow a remote attacker to create a denial-of-service
condition.
SOLUTION: Upgrade to the appropriate version.
______________________________________________________________________________
VULNERABILITY The risk is LOW. May allow a remote attacker to create a
ASSESSMENT: denial-of-service condition.
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LINKS:
CIAC BULLETIN: http://www.ciac.org/ciac/bulletins/r-177.shtml
ORIGINAL BULLETIN: http://www.kb.cert.org/vuls/id/920689
ADDITIONAL LINK: https://rhn.redhat.com/errata/RHSA-2007-0169.html
CVE: http://www.cve.mitre.org/cgi-bin/cvename.cgi?name=
CVE-2007-1000
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REVISION HISTORY:
05/01/2007 - revised R-177 to add a link to Red Hat RHSA-2007:0169-2 for RHEL
Desktop Workstation (v. 5 client), Red Hat Enterprise Linux
(v. 5 server), and Red Hat Enterprise Linux Desktop (v. 5 client).

[***** Start US-CERT Vulnerability Note VU#920689 *****]

Vulnerability Note VU#920689
Linux Kernel vulnerable to DoS via the ipv6_getsockopt_sticky() function

Overview

The Linux Kernel contains a vulnerability that may allow a remote attacker to
create a denial-of-service condition.

I. Description
Internet Protocol version 6 (IPv6) is a IP standard that is designed to
replace the Internet Protocol version 4 (IPv4). The Linux kernel provides IPv6
support, and Linux vendors may enable IPv6 by default.
The Linux kernel contains a condition that may allow a null pointer to be
dereferenced during a memory allocation by the ipv6_getsockopt_sticky() function
in net/ipv6/ipv6_sockglue.c. Note that this vulnerability may be present in both
the 2.4 and 2.6 versions of the Linux kernel.

II. Impact
A remote unauthenticated attacker may be able to cause the kernel to panic (Oops)
on a vulnerable system, thereby creating a denial of service.. If the vulnerable
software is running on a server, all clients that rely on the server will also be
affected.

III. Solution
Upgrade
This issue has been addressed in Linux kernel version 2.6.20.2. Users who do not
compile their kernels from source should contact their operating system vendor
for updated kernel packages.

Disable IPv6

If IPv6 functionality is not needed, disabling it may mitigate this vulnerability.
Adding alias net-pf-10 ipv6 off to your modprobe configuration file and rebooting
may disable IPv6 functionality.

Systems Affected
Vendor Status Date Updated
Linux Kernel Archives Vulnerable 13-Mar-2007

References

http://bugzilla.kernel.org/show_bug.cgi?id=8134
http://kernel.org/pub/linux/kernel/v2.6/ChangeLog-2.6.20.2
https://www.securecoding.cert.org/confluence/display/seccode/Do+not+dereference+
invalid+pointers
http://www.kernel.org/
http://secunia.com/advisories/24493/
http://en.wikipedia.org/wiki/Ipv6
http://en.wikipedia.org/wiki/Ipv4

Credit
Thanks to Chris Wright for information that was used in this report.

This document was written by Ryan Giobbi.

Other Information
Date Public 03/12/2007
Date First Published 03/13/2007 01:54:21 PM
Date Last Updated 03/13/2007
CERT Advisory
CVE Name CVE-2007-1000
Metric 3.71
Document Revision 13

[***** End US-CERT Vulnerability Note VU#920689 *****]
_______________________________________________________________________________

CIAC wishes to acknowledge the contributions of US-CERT for the
information contained in this bulletin.
_______________________________________________________________________________

CIAC, the Computer Incident Advisory Capability, is the computer
security incident response team for the U.S. Department of Energy
(DOE) and the emergency backup response team for the National
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