May 2005

ID: 00411
Ref: 380/2005
Date: 13 May 2005:15:33:45
Version: 1

---

Title: FreeBSD Security Advisory: FreeBSD-SA-05:09.htt - information disclosure when using HTT
Abstract:
Vendors affected: FreeBSD
Operating systems affected: FreeBSD
Applications affected: FreeBSD

---

Title
=====

FreeBSD Security Advisory: FreeBSD-SA-05:09.htt - information disclosure when using HTT

Detail
======

A security flaw involving operating systems running on Hyper-Threading
Technology processors was has been reported. Complete details are not
available at the time of this writing. However, a workaround has been
issued. It is expected that more details will be available tomorrow, at
which time a revised version of this advisory will be published.



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=============================================================================
FreeBSD-SA-05:09.htt Security Advisory
The FreeBSD Project

Topic: information disclosure when using HTT

Category: core
Module: sys
Announced: 2005-05-13
Revised: 2005-05-13
Credits: Colin Percival
Affects: All FreeBSD/i386 and FreeBSD/amd64 releases.
Corrected: 2005-05-13 00:13:00 UTC (RELENG_5, 5.4-STABLE)
2005-05-13 00:13:00 UTC (RELENG_5_4, 5.4-RELEASE-p1)
2005-05-13 00:13:00 UTC (RELENG_5_3, 5.3-RELEASE-p15)
2005-05-13 00:13:00 UTC (RELENG_4, 4.11-STABLE)
2005-05-13 00:13:00 UTC (RELENG_4_11, 4.11-RELEASE-p9)
2005-05-13 00:13:00 UTC (RELENG_4_10, 4.10-RELEASE-p14)
CVE Name: CAN-2005-0109

For general information regarding FreeBSD Security Advisories,
including descriptions of the fields above, security branches, and the
following sections, please visit
.

I. Background

"Hyper-Threading Technology" is the name used for the implementation of
simultaneous multithreading on Intel Pentium 4, Mobile Pentium 4, and
Xeon processors.

II. Problem Description

A security flaw involving operating systems running on Hyper-Threading
Technology processors was has been reported. Complete details are not
available at the time of this writing. However, a workaround has been
issued. It is expected that more details will be available tomorrow, at
which time a revised version of this advisory will be published.

III. Impact

Information may be disclosed to local users, allowing in many cases for
privilege escalation.

IV. Workaround

Systems not using processors with Hyper-Threading support are not
affected by this issue. On systems which are affected, the security
flaw can be eliminated by setting the "machdep.hlt_logical_cpus"
tunable:

# echo "machdep.hlt_logical_cpus=1" >> /boot/loader.conf

The system must be rebooted in order for tunables to take effect.

Use of this workaround is not recommended on "dual-core" systems, as
this workaround will also disable one of the processor cores.

V. Solution

Perform one of the following:

1) Upgrade your vulnerable system to 4-STABLE or 5-STABLE, or to the
RELENG_5_4, RELENG_5_3, RELENG_4_11, or RELENG_4_10 security branch
dated after the correction date.

2) To patch your present system:

The following patches have been verified to apply to FreeBSD 4.10,
4.11, 5.3, and 5.4 systems.

a) Download the relevant patch from the location below and verify the
detached PGP signature using your PGP utility.

[FreeBSD 4.10]
# fetch ftp://ftp.FreeBSD.org/pub/FreeBSD/CERT/patches/SA-05:09/htt410.patch
# fetch ftp://ftp.FreeBSD.org/pub/FreeBSD/CERT/patches/SA-05:09/htt410.patch.asc

[FreeBSD 4.11]
# fetch ftp://ftp.FreeBSD.org/pub/FreeBSD/CERT/patches/SA-05:09/htt411.patch
# fetch ftp://ftp.FreeBSD.org/pub/FreeBSD/CERT/patches/SA-05:09/htt411.patch.asc

[FreeBSD 5.x]
# fetch ftp://ftp.FreeBSD.org/pub/FreeBSD/CERT/patches/SA-05:09/htt5.patch
# fetch ftp://ftp.FreeBSD.org/pub/FreeBSD/CERT/patches/SA-05:09/htt5.patch.asc

b) Apply the patch.

# cd /usr/src
# patch < /path/to/patch

c) Recompile your kernel as described in
and reboot the
system.

NOTE: For users that are certain that their environment is not affected
by this vulnerability, such as single-user systems, Hyper-Threading
Technology may be re-enabled by setting the tunable
"machdep.hyperthreading_allowed".

VI. Correction details

The following list contains the revision numbers of each file that was
corrected in FreeBSD.

Branch Revision
Path
- - -------------------------------------------------------------------------
RELENG_4
src/sys/i386/i386/mp_machdep.c 1.115.2.23
src/sys/i386/include/cpufunc.h 1.96.2.4
RELENG_4_11
src/UPDATING 1.73.2.91.2.10
src/sys/conf/newvers.sh 1.44.2.39.2.13
src/sys/i386/i386/mp_machdep.c 1.115.2.22.2.1
src/sys/i386/include/cpufunc.h 1.96.2.3.12.1
RELENG_4_10
src/UPDATING 1.73.2.90.2.15
src/sys/conf/newvers.sh 1.44.2.34.2.16
src/sys/i386/i386/mp_machdep.c 1.115.2.20.2.1
src/sys/i386/include/cpufunc.h 1.96.2.3.10.1
RELENG_5
src/sys/amd64/amd64/mp_machdep.c 1.242.2.11
src/sys/amd64/include/cpufunc.h 1.145.2.1
src/sys/i386/i386/mp_machdep.c 1.235.2.10
src/sys/i386/include/cpufunc.h 1.142.2.1
RELENG_5_4
src/UPDATING 1.342.2.24.2.10
src/sys/amd64/amd64/mp_machdep.c 1.242.2.7.2.4
src/sys/amd64/include/cpufunc.h 1.145.6.1
src/sys/conf/newvers.sh 1.62.2.18.2.6
src/sys/i386/i386/mp_machdep.c 1.235.2.6.2.3
src/sys/i386/include/cpufunc.h 1.142.6.1
RELENG_5_3
src/UPDATING 1.342.2.13.2.18
src/sys/amd64/amd64/mp_machdep.c 1.242.2.2.2.2
src/sys/amd64/include/cpufunc.h 1.145.4.1
src/sys/conf/newvers.sh 1.62.2.15.2.20
src/sys/i386/i386/mp_machdep.c 1.235.2.3.2.2
src/sys/i386/include/cpufunc.h 1.142.4.1
- - -------------------------------------------------------------------------

VII. References

http://www.daemonology.net/hyperthreading-considered-harmful/

The latest revision of this advisory is available at
ftp://ftp.freebsd.org/pub/FreeBSD/CERT/advisories/FreeBSD-SA-05:09.htt.asc
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