—–BEGIN PGP SIGNED MESSAGE—–
Hash: SHA512
=============================================================================
FreeBSD-SA-19:07.mds Security Advisory
The FreeBSD Project
Topic: Microarchitectural Data Sampling (MDS)
Category: core
Module: kernel
Announced: 2019-05-14
Credits: Refer to Intel’s security advisory at the URL below for
detailed acknowledgements.
Affects: All supported versions of FreeBSD.
Corrected: 2019-05-14 17:04:00 UTC (stable/12, 12.0-STABLE)
2019-05-14 23:19:08 UTC (releng/12.0, 12.0-RELEASE-p4)
2019-05-14 17:05:02 UTC (stable/11, 11.3-PRERELEASE)
2019-05-14 23:20:16 UTC (releng/11.2, 11.2-RELEASE-p10)
CVE Name: CVE-2018-12126, CVE-2018-12127, CVE-2018-12130,
CVE-2019-11091
For general information regarding FreeBSD Security Advisories,
including descriptions of the fields above, security branches, and the
following sections, please visit <URL:https://security.FreeBSD.org/>.
I. Background
Modern processors make use of speculative execution, an optimization
technique which performs some action in advance of knowing whether the
result will actually be used.
II. Problem Description
On some Intel processors utilizing speculative execution a local process may
be able to infer stale information from microarchitectural buffers to obtain
a memory disclosure.
III. Impact
An attacker may be able to read secret data from the kernel or from a
process when executing untrusted code (for example, in a web browser).
IV. Workaround
No workaround is available.
Systems with users or processors in different trust domains should disable
Hyper-Threading by setting the machdep.hyperthreading_allowed tunable to 0:
# echo ‘machdep.hyperthreading_allowed=0 >> /boot/loader.conf’
# shutdown
V. Solution
Perform one of the following:
Update CPU microcode, upgrade your vulnerable system to a supported FreeBSD
stable or release / security branch (releng) dated after the correction date,
evaluate mitigation and Hyper Threading controls, and reboot the system.
New CPU microcode may be available in a BIOS update from your system vendor,
or by installing the devcpu-data package or sysutils/devcpu-data port.
Ensure that the BIOS update or devcpu-data package is dated after 2014-05-14.
If using the package or port the microcode update can be applied at boot time
by adding the following lines to the system’s /boot/loader.conf:
cpu_microcode_load=”YES”
cpu_microcode_name=”/boot/firmware/intel-ucode.bin”
Microcode updates can also be applied while the system is running. See
cpucontrol(8) for details.
1) To update your vulnerable system via a binary patch:
Systems running a RELEASE version of FreeBSD on the i386 or amd64
platforms can be updated via the freebsd-update(8) utility:
# freebsd-update fetch
# freebsd-update install
Follow additional details under “Mitigation Configuration” below.
2) To update your vulnerable system via a source code patch:
The following patches have been verified to apply to the applicable
FreeBSD release branches.
a) Download the relevant patch from the location below, and verify the
detached PGP signature using your PGP utility.
[FreeBSD 12.0-STABLE]
# fetch https://security.FreeBSD.org/patches/SA-19:07/mds.12-stable.patch
# fetch https://security.FreeBSD.org/patches/SA-19:07/mds.12-stable.patch.asc
# gpg –verify mds.12-stable.patch.asc
[FreeBSD 12.0-RELEASE]
# fetch https://security.FreeBSD.org/patches/SA-19:07/mds.12.0.patch
# fetch https://security.FreeBSD.org/patches/SA-19:07/mds.12.0.patch.asc
# gpg –verify mds.12.0.patch.asc
[FreeBSD 11.3-PRERELEASE]
# fetch https://security.FreeBSD.org/patches/SA-19:07/mds.11-stable.patch
# fetch https://security.FreeBSD.org/patches/SA-19:07/mds.11-stable.patch.asc
# gpg –verify mds.11-stable.patch.asc
[FreeBSD 11.2-RELEASE]
# fetch https://security.FreeBSD.org/patches/SA-19:07/mds.11.2.patch
# fetch https://security.FreeBSD.org/patches/SA-19:07/mds.11.2.patch.asc
# gpg –verify mds.11.2.patch.asc
b) Apply the patch. Execute the following commands as root:
# cd /usr/src
# patch < /path/to/patch
c) Recompile your kernel as described in
<URL:https://www.FreeBSD.org/handbook/kernelconfig.html>.
Mitigation Configuration
Systems with users, processes, or virtual machines in different trust
domains should disable Hyper-Threading by setting the
machdep.hyperthreading_allowed tunable to 0:
# echo machdep.hyperthreading_allowed=0 >> /boot/loader.conf
To activate the MDS mitigation set the hw.mds_disable sysctl. The settings
are:
0 – mitigation disabled
1 – VERW instruction (microcode) mitigation enabled
2 – Software sequence mitigation enabled (not recommended)
3 – Automatic VERW or Software selection
Automatic mode uses the VERW instruction if supported by the CPU / microcode,
or software sequences if not. To enable automatic mode at boot:
# echo hw.mds_disable=3 >> /etc/sysctl.conf
Reboot the system:
# shutdown -r +10min “Security update”
Check the mitigation status:
# sysctl hw.mds_disable_state
hw.mds_disable_state: software Silvermont
VI. Correction details
The following list contains the correction revision numbers for each
affected branch.
Branch/path Revision
– ————————————————————————-
stable/12/ r347567
releng/12.0/ r346594
stable/11/ r347568
releng/11.2/ r347595
– ————————————————————————-
To see which files were modified by a particular revision, run the
following command, replacing NNNNNN with the revision number, on a
machine with Subversion installed:
# svn diff -cNNNNNN –summarize svn://svn.freebsd.org/base
Or visit the following URL, replacing NNNNNN with the revision number:
<URL:https://svnweb.freebsd.org/base?view=revision&revision=NNNNNN>
VII. References
<URL:https://www.intel.com/content/www/us/en/security-center/advisory/intel-sa-00233.html>
<URL:https://www.intel.com/content/www/us/en/architecture-and-technology/mds.html>
The latest revision of this advisory is available at
<URL:https://security.FreeBSD.org/advisories/FreeBSD-SA-19:07.mds.asc>
—–BEGIN PGP SIGNATURE—–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=QUYl
—–END PGP SIGNATURE—–
_______________________________________________
freebsd-security-notifications@freebsd.org mailing list
https://lists.freebsd.org/mailman/listinfo/freebsd-security-notifications
To unsubscribe, send any mail to “freebsd-security-notifications-unsubscribe@freebsd.org”
