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============================================================================= FreeBSD-SA-04:06.ipv6 Security Advisory The FreeBSD Project
Topic: setsockopt(2) IPv6 sockets input validation error
Category: core Module: kernel Announced: 2004-03-29 Credits: Katsuhisa ABE, Colin Percival Affects: FreeBSD 5.2-RELEASE Corrected: 2004-03-29 14:01:33 UTC (RELENG_5_2, 5.2.1-RELEASE-p4) CVE Name: CAN-2004-0370 FreeBSD only: YES
For general information regarding FreeBSD Security Advisories, including descriptions of the fields above, security branches, and the following sections, please visit <URL:http://www.freebsd.org/security/>.
IPv6 is a new Internet Protocol, designed to replace (and avoid many of the problems with) the current Internet Protocol (version 4). FreeBSD uses the KAME Project IPv6 implementation.
Applications may manipulate the behavior of an IPv6 socket using the setsockopt(2) system call.
II. Problem Description
A programming error in the handling of some IPv6 socket options within the setsockopt(2) system call may result in memory locations being accessed without proper validation. While the problem originates in code from the KAME Project, it does not affect other operating systems.
It may be possible for a local attacker to read portions of kernel memory, resulting in disclosure of sensitive information. A local attacker can cause a system panic.
Do one of the following:
1) Disable IPv6 entirely by following these steps:
Remove or comment out any lines mentioning `INET6' from your kernel configuration file, and recompile your kernel as described in <URL:http://www.freebsd.org/handbook/kernelconfig.html>.
Reboot your system.
2) If all untrusted users are confined within a jail(8), ensure that the security.jail.socket_unixiproute_only sysctl is set to 1 and verify that no IPv6 sockets are currently open:
This will restrict jailed processes to creating UNIX domain, IPv4, and routing sockets, which are not vulnerable to this problem; note however that processes inside a jail may still be able to inherit IPv6 sockets from outside the jail, so this may not be sufficient for all systems.
Do one of the following:
1) Upgrade your vulnerable system to the RELENG_5_2 security branch dated after the correction date.
2) To patch your present system:
a) Download the relevant patch from the location below, and verify the detached PGP signature using your PGP utility.
b) Execute the following commands as root:
c) Recompile the kernel as described in <URL:http://www.freebsd.org/handbook/kernelconfig.html> and reboot the system.
d) Install updated kernel headers.
VI. Correction details
The following list contains the revision numbers of each file that was corrected in FreeBSD.
Branch Revision Path
RELENG_5_2 src/UPDATING 1.282.2.12 src/sys/netinet6/ip6_output.c 18.104.22.168 src/sys/netinet/ip6.h 22.214.171.124 src/sys/conf/newvers.sh 126.96.36.199
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