Bug 1222453

Summary: VUL-0: CVE-2024-2201: xen: x86: Native Branch History Injection (XSA-456)
Product: [Novell Products] SUSE Security Incidents Reporter: Gianluca Gabrielli <gianluca.gabrielli>
Component: IncidentsAssignee: Charles Arnold <carnold>
Status: IN_PROGRESS --- QA Contact: Security Team bot <security-team>
Severity: Normal    
Priority: P3 - Medium CC: jbeulich, meissner, rfrohl
Version: unspecified   
Target Milestone: ---   
Hardware: Other   
OS: Other   
URL: https://smash.suse.de/issue/368751/
Whiteboard: CVSSv3.1:SUSE:CVE-2024-2201:5.1:(AV:L/AC:H/PR:N/UI:N/S:U/C:H/I:N/A:N)
Found By: --- Services Priority:
Business Priority: Blocker: ---
Marketing QA Status: --- IT Deployment: ---
Bug Depends on:    
Bug Blocks: 1217339    
Attachments: xsa456.bundle

Description Gianluca Gabrielli 2024-04-08 10:38:05 UTC 
Created attachment 874127 [details]
xsa456.bundle

-----BEGIN PGP SIGNED MESSAGE-----
Hash: SHA256

            Xen Security Advisory CVE-2024-2201 / XSA-456

                 x86: Native Branch History Injection

              *** EMBARGOED UNTIL 2024-04-09 17:00 UTC ***

ISSUE DESCRIPTION
=================

In August 2022, researchers at VU Amsterdam disclosed Spectre-BHB.

Spectre-BHB was discussed in XSA-398.  At the time, the susceptibility
of Xen to Spectre-BHB was uncertain so no specific action was taken in
XSA-398.  However, various changes were made thereafter in upstream Xen
as a consequence; more on these later.

VU Amsterdam have subsequently adjusted the attack to be pulled off
entirely from userspace, without the aid of a managed runtime in the
victim context.

For more details, see:
  https://vusec.net/projects/ XXX - TBC
  https://vusec.net/projects/bhi-spectre-bhb
  https://www.intel.com/content/www/us/en/developer/articles/technical/software-security-guidance/technical-documentation/branch-history-injection.html
  https://xenbits.xen.org/xsa/advisory-398.html

IMPACT
======

An attacker might be able to infer the contents of arbitrary host
memory, including memory assigned to other guests.

VULNERABLE SYSTEMS
==================

Systems running all versions of Xen are affected.

Only Intel x86 CPUs are potentially affected.  CPUs from other
manufacturers are not known to be affected.

A wide range of Intel CPUs employ Branch History prediction techniques.
However for older CPUs existing Spectre-v2 mitigations (XSA-254) are
believed to be sufficient to mitigate Native-BHI.

Therefore, the rest of the discussion will be limited in scope to the
CPUs for which a change in behaviour is expected.  These are believed to
be all CPUs with eIBRS (Enhanced IBRS, a.k.a. IBRS_ALL or IBRS_ATT).
eIBRS signifies a hardware adjustment (mode-tagged indirect predictions)
designed to combat Spectre-v2, available in CPUs from 2019 onwards.

To determine if a system has eIBRS, run `xen-cpuid -v` in dom0, looking for
the string "eibrs" in the Dynamic Raw block of information.  e.g.

  # xen-cpuid -v
  ...
  Dynamic sets:
  Raw                             ...
    ...
    [16] MSR_ARCH_CAPS.lo         ... eibrs ...
    ...
  ...

Be aware that the Static sets are compile time information so will include the
string "eibrs" irrespective of hardware support.  If there is no row for "[16]
MSR_ARCH_CAPS.lo" then the fixes for XSA-435 are missing.

MITIGATION
==========

There are no mitigations.

RESOLUTION
==========

WARNING: Fixes are still in development; this is not a complete resolution!!

Attached is an interim git bundle containing XSAs 454, 455, the prerequisite
backports of 456 from staging, and some parts of the 456 fix which are ready.
It does not contain the whole 456 fix.

See https://git-scm.com/docs/git-bundle for information on git bundles.

In Xen 4.17, in response to the original Spectre-BHB, CET-IBT support was
added to Xen to use on capable hardware.  It also came with work to remove
unnecessary function pointers, and to de-virtualise function pointers at boot,
as both a performance and hardening improvement.  This work has been steadily
continuing since, and every removed/de-virtualised function pointer reduces
the options available to an adversary trying to mount a Native-BHI attack.

xsa456.bundle

$ sha256sum xsa456*
c5a4365b0168e179da19032a3f1a4103704c19d0d2b6ab41dec7b5cb715ed30b  xsa456.bundle
$

DEPLOYMENT DURING EMBARGO
=========================

Deployment of the patches and/or mitigations described above (or
others which are substantially similar) is permitted during the
embargo, even on public-facing systems with untrusted guest users and
administrators.

But: Distribution of updated software is prohibited (except to other
members of the predisclosure list).

Predisclosure list members who wish to deploy significantly different
patches and/or mitigations, please contact the Xen Project Security
Team.

(Note: this during-embargo deployment notice is retained in
post-embargo publicly released Xen Project advisories, even though it
is then no longer applicable.  This is to enable the community to have
oversight of the Xen Project Security Team's decisionmaking.)

For more information about permissible uses of embargoed information,
consult the Xen Project community's agreed Security Policy:
  http://www.xenproject.org/security-policy.html
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Comment 5 OBSbugzilla Bot 2024-04-10 04:55:04 UTC 
This is an autogenerated message for OBS integration:
This bug (1222453) was mentioned in
https://build.opensuse.org/request/show/1166538 Factory / xen
Comment 6 Johannes Segitz 2024-04-10 07:54:04 UTC 
public
Comment 8 Maintenance Automation 2024-04-12 16:30:43 UTC 
SUSE-SU-2024:1259-1: An update that solves three vulnerabilities and has one security fix can now be installed.

Category: security (moderate)
Bug References: 1027519, 1221984, 1222302, 1222453
CVE References: CVE-2023-46842, CVE-2024-2201, CVE-2024-31142
Maintenance Incident: [SUSE:Maintenance:33341](https://smelt.suse.de/incident/33341/)
Sources used:
openSUSE Leap 15.4 (src):
 xen-4.16.6_02-150400.4.55.1
openSUSE Leap Micro 5.3 (src):
 xen-4.16.6_02-150400.4.55.1
openSUSE Leap Micro 5.4 (src):
 xen-4.16.6_02-150400.4.55.1
SUSE Linux Enterprise Micro for Rancher 5.3 (src):
 xen-4.16.6_02-150400.4.55.1
SUSE Linux Enterprise Micro 5.3 (src):
 xen-4.16.6_02-150400.4.55.1
SUSE Linux Enterprise Micro for Rancher 5.4 (src):
 xen-4.16.6_02-150400.4.55.1
SUSE Linux Enterprise Micro 5.4 (src):
 xen-4.16.6_02-150400.4.55.1

NOTE: This line indicates an update has been released for the listed product(s). At times this might be only a partial fix. If you have questions please reach out to maintenance coordination.
Comment 9 Maintenance Automation 2024-04-15 20:30:08 UTC 
SUSE-SU-2024:1295-1: An update that solves three vulnerabilities and has one security fix can now be installed.

Category: security (moderate)
Bug References: 1027519, 1221984, 1222302, 1222453
CVE References: CVE-2023-46842, CVE-2024-2201, CVE-2024-31142
Maintenance Incident: [SUSE:Maintenance:33340](https://smelt.suse.de/incident/33340/)
Sources used:
openSUSE Leap 15.5 (src):
 xen-4.17.4_02-150500.3.30.1
SUSE Linux Enterprise Micro 5.5 (src):
 xen-4.17.4_02-150500.3.30.1
Basesystem Module 15-SP5 (src):
 xen-4.17.4_02-150500.3.30.1
Server Applications Module 15-SP5 (src):
 xen-4.17.4_02-150500.3.30.1

NOTE: This line indicates an update has been released for the listed product(s). At times this might be only a partial fix. If you have questions please reach out to maintenance coordination.
Comment 13 Maintenance Automation 2024-05-07 08:30:04 UTC 
SUSE-SU-2024:1541-1: An update that solves three vulnerabilities and has one security fix can now be installed.

Category: security (moderate)
Bug References: 1027519, 1221984, 1222302, 1222453
CVE References: CVE-2023-46842, CVE-2024-2201, CVE-2024-31142
Maintenance Incident: [SUSE:Maintenance:33626](https://smelt.suse.de/incident/33626/)
Sources used:
SUSE Linux Enterprise Software Development Kit 12 SP5 (src):
 xen-4.12.4_48-3.109.1
SUSE Linux Enterprise Server for SAP Applications 12 SP5 (src):
 xen-4.12.4_48-3.109.1
SUSE Linux Enterprise High Performance Computing 12 SP5 (src):
 xen-4.12.4_48-3.109.1
SUSE Linux Enterprise Server 12 SP5 (src):
 xen-4.12.4_48-3.109.1

NOTE: This line indicates an update has been released for the listed product(s). At times this might be only a partial fix. If you have questions please reach out to maintenance coordination.
Comment 14 Maintenance Automation 2024-05-07 08:30:07 UTC 
SUSE-SU-2024:1540-1: An update that solves three vulnerabilities can now be installed.

Category: security (moderate)
Bug References: 1221984, 1222302, 1222453
CVE References: CVE-2023-46842, CVE-2024-2201, CVE-2024-31142
Maintenance Incident: [SUSE:Maintenance:33625](https://smelt.suse.de/incident/33625/)
Sources used:
openSUSE Leap 15.3 (src):
 xen-4.14.6_14-150300.3.72.1
SUSE Linux Enterprise Micro 5.1 (src):
 xen-4.14.6_14-150300.3.72.1
SUSE Linux Enterprise Micro 5.2 (src):
 xen-4.14.6_14-150300.3.72.1
SUSE Linux Enterprise Micro for Rancher 5.2 (src):
 xen-4.14.6_14-150300.3.72.1

NOTE: This line indicates an update has been released for the listed product(s). At times this might be only a partial fix. If you have questions please reach out to maintenance coordination.
Comment 15 Gianluca Gabrielli 2024-05-09 07:58:35 UTC 
            Xen Security Advisory CVE-2024-2201 / XSA-456
                              version 3

                 x86: Native Branch History Injection

UPDATES IN VERSION 3
====================

Issues were found with the original code changes.  See the bottom of the
Resolution section for how to obtain those.

[...]

RESOLUTION
==========

[...]

Issues were in those found subsequently.  To address those, newer commits
from the stable branches need updating to, in particular

stable-4.15	056500003eb44314cb90f2e3e7b2d405e86b5657
stable-4.16	d0e8f8ffbb19b5df5f767328baeb54c069b08e6a
stable-4.17	effcf70f020ff12d34c80e2abde0ecb00ce92bda
stable-4.18	f0ff1d9cb96041a84a24857a6464628240deed4f

For 4.15, since we're closing the branch, RELEASE-4.15.7 was tagged in
addition; other release activities - as per above - will follow.
Comment 18 Maintenance Automation 2024-07-16 16:30:09 UTC 
SUSE-SU-2024:2535-1: An update that solves six vulnerabilities and has one security fix can now be installed.

Category: security (important)
Bug References: 1214083, 1221332, 1221334, 1221984, 1222302, 1222453, 1227355
CVE References: CVE-2023-28746, CVE-2023-46842, CVE-2024-2193, CVE-2024-2201, CVE-2024-31142, CVE-2024-31143
Maintenance Incident: [SUSE:Maintenance:33138](https://smelt.suse.de/incident/33138/)
Sources used:
SUSE Linux Enterprise High Performance Computing 15 SP2 LTSS 15-SP2 (src):
 xen-4.13.5_12-150200.3.93.1
SUSE Linux Enterprise Server 15 SP2 LTSS 15-SP2 (src):
 xen-4.13.5_12-150200.3.93.1
SUSE Linux Enterprise Server for SAP Applications 15 SP2 (src):
 xen-4.13.5_12-150200.3.93.1

NOTE: This line indicates an update has been released for the listed product(s). At times this might be only a partial fix. If you have questions please reach out to maintenance coordination.
Comment 19 Maintenance Automation 2024-07-16 16:30:11 UTC 
SUSE-SU-2024:2534-1: An update that solves two vulnerabilities and has one security fix can now be installed.

Category: security (important)
Bug References: 1027519, 1222453, 1227355
CVE References: CVE-2024-2201, CVE-2024-31143
Maintenance Incident: [SUSE:Maintenance:34727](https://smelt.suse.de/incident/34727/)
Sources used:
SUSE Linux Enterprise Software Development Kit 12 SP5 (src):
 xen-4.12.4_50-3.112.1
SUSE Linux Enterprise Server for SAP Applications 12 SP5 (src):
 xen-4.12.4_50-3.112.1
SUSE Linux Enterprise High Performance Computing 12 SP5 (src):
 xen-4.12.4_50-3.112.1
SUSE Linux Enterprise Server 12 SP5 (src):
 xen-4.12.4_50-3.112.1

NOTE: This line indicates an update has been released for the listed product(s). At times this might be only a partial fix. If you have questions please reach out to maintenance coordination.
Comment 20 Maintenance Automation 2024-07-16 16:30:15 UTC 
SUSE-SU-2024:2533-1: An update that solves two vulnerabilities can now be installed.

Category: security (important)
Bug References: 1222453, 1227355
CVE References: CVE-2024-2201, CVE-2024-31143
Maintenance Incident: [SUSE:Maintenance:34726](https://smelt.suse.de/incident/34726/)
Sources used:
openSUSE Leap 15.3 (src):
 xen-4.14.6_16-150300.3.75.1
SUSE Linux Enterprise High Performance Computing LTSS 15 SP3 (src):
 xen-4.14.6_16-150300.3.75.1
SUSE Linux Enterprise Server 15 SP3 LTSS 15-SP3 (src):
 xen-4.14.6_16-150300.3.75.1
SUSE Linux Enterprise Server for SAP Applications 15 SP3 (src):
 xen-4.14.6_16-150300.3.75.1
SUSE Enterprise Storage 7.1 (src):
 xen-4.14.6_16-150300.3.75.1
SUSE Linux Enterprise Micro 5.1 (src):
 xen-4.14.6_16-150300.3.75.1
SUSE Linux Enterprise Micro 5.2 (src):
 xen-4.14.6_16-150300.3.75.1
SUSE Linux Enterprise Micro for Rancher 5.2 (src):
 xen-4.14.6_16-150300.3.75.1

NOTE: This line indicates an update has been released for the listed product(s). At times this might be only a partial fix. If you have questions please reach out to maintenance coordination.