Bug 1194581 - (CVE-2022-23034) VUL-0: CVE-2022-23034: xen: a PV guest could DoS Xen while unmapping a grant (XSA-394)
(CVE-2022-23034)
VUL-0: CVE-2022-23034: xen: a PV guest could DoS Xen while unmapping a grant ...
Status: RESOLVED FIXED
Classification: Novell Products
Product: SUSE Security Incidents
Classification: Novell Products
Component: Incidents
unspecified
Other Other
: P3 - Medium : Normal
: ---
Assigned To: Security Team bot
Security Team bot
https://smash.suse.de/issue/320172/
CVSSv3.1:SUSE:CVE-2022-23034:4.0:(AV:...
:
Depends on:
Blocks:
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Reported: 2022-01-12 09:52 UTC by Thomas Leroy
Modified: 2022-02-21 15:08 UTC (History)
3 users (show)

See Also:
Found By: ---
Services Priority:
Business Priority:
Blocker: ---
Marketing QA Status: ---
IT Deployment: ---


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Description Thomas Leroy 2022-01-12 09:52:17 UTC
-----BEGIN PGP SIGNED MESSAGE-----
Hash: SHA256

            Xen Security Advisory CVE-2022-23034 / XSA-394

           A PV guest could DoS Xen while unmapping a grant

              *** EMBARGOED UNTIL 2022-01-25 12:00 UTC ***

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

To address XSA-380, reference counting was introduced for grant
mappings. PV guests can request two forms of mappings.  When both are in
use for any individual mapping, unmapping of such a mapping can be
requested in two steps.  The reference count for such a mapping would
then mistakenly be decremented twice.  Underflow of the counters gets
detected, resulting in the triggering of a hypervisor bug check.

IMPACT
======

Malicious guest kernels may be able to mount a Denial of Service (DoS)
attack affecting the entire system.

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

All Xen versions from at least 3.2 onwards are vulnerable in principle,
if they have the XSA-380 fixes applied.

Only x86 systems are vulnerable.  Arm systems are not vulnerable.

Only x86 PV guests can leverage the vulnerability.  x86 HVM and PVH
guests cannot leverage the vulnerability.  Additionally from Xen 4.13
onwards x86 PV guests can leverage this vulnerability only when being
granted access to pages owned by another domain.

MITIGATION
==========

Not running PV guests will avoid the vulnerability.

- From Xen 4.13 onwards, running PV guests in SILO mode will also avoid
the vulnerability.

RESOLUTION
==========

Applying the appropriate attached patch resolves this issue.

Note that patches for released versions are generally prepared to
apply to the stable branches, and may not apply cleanly to the most
recent release tarball.  Downstreams are encouraged to update to the
tip of the stable branch before applying these patches.

xsa394.patch           xen-unstable - Xen 4.13.x
xsa394-4.12.patch      Xen 4.12.x

$ sha256sum xsa394*
93f4d3b58d49ba239115753c9905b7c3720b438c48ef8fb701f15081aa317159  xsa394.meta
f2a3420e8d3eb1cf728f90d3c352ace0d3c67f7933201ce9b784d63afaeaa179  xsa394.patch
ee93797546ac9e82f98211366f9acc733332b0d5ab7ef73840c2acd2bb1439ca  xsa394-4.12.patch
$

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

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

HOWEVER, deployment of the mitigations described above is NOT permitted
during the embargo on public-facing systems with untrusted guest users
and administrators.  This is because such a configuration change is
recognizable by the affected guests.

AND: 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 6 Thomas Leroy 2022-01-12 16:51:58 UTC
The incorrect refcount decrementing was introduced in XSA-380, whose patch was released in the following codestreams:
- SUSE:SLE-11-SP4:Update	4.4.4_48-61.64.1	
- SUSE:SLE-12-SP2:Update 	4.7.6_14-43.76.1	
- SUSE:SLE-12-SP3:Update 	4.9.4_18-3.86.1	
- SUSE:SLE-12-SP4:Update 	4.11.4_18-2.54.1	
- SUSE:SLE-12-SP5:Update	4.12.4_10-3.42.1	
- SUSE:SLE-15:Update 	        	
- SUSE:SLE-15-SP1:Update 	4.12.3_08-3.28.1	
- SUSE:SLE-15-SP2:Update 	4.13.1_06-3.7.1	
- SUSE:SLE-15-SP3:Update

Therefore, I think these codestreams are affected. 
However, I can't find the XSA-380 commit in openSUSE:Factory (and openSUSE:Leap:15.3:Update), am I missing something?
Comment 7 Charles Arnold 2022-01-12 18:36:21 UTC
(In reply to Thomas Leroy from comment #6)
> The incorrect refcount decrementing was introduced in XSA-380, whose patch
> was released in the following codestreams:
> - SUSE:SLE-11-SP4:Update	4.4.4_48-61.64.1	
> - SUSE:SLE-12-SP2:Update 	4.7.6_14-43.76.1	
> - SUSE:SLE-12-SP3:Update 	4.9.4_18-3.86.1	
> - SUSE:SLE-12-SP4:Update 	4.11.4_18-2.54.1	
> - SUSE:SLE-12-SP5:Update	4.12.4_10-3.42.1	
> - SUSE:SLE-15:Update 	        	
> - SUSE:SLE-15-SP1:Update 	4.12.3_08-3.28.1	
> - SUSE:SLE-15-SP2:Update 	4.13.1_06-3.7.1	
> - SUSE:SLE-15-SP3:Update
> 
> Therefore, I think these codestreams are affected. 
> However, I can't find the XSA-380 commit in openSUSE:Factory (and
> openSUSE:Leap:15.3:Update), am I missing something?

We don't need to worry about the openSUSE releases. Leap is handled automatically
when SLE is updated. I'll submit to Factory after the fixes go public if they are
required there but we don't need to track security fixes in Factory because there
is no formal support for Factory/Tumbleweed.
Comment 8 Thomas Leroy 2022-01-13 07:53:32 UTC
(In reply to Charles Arnold from comment #7)
> We don't need to worry about the openSUSE releases. Leap is handled
> automatically
> when SLE is updated. I'll submit to Factory after the fixes go public if
> they are
> required there but we don't need to track security fixes in Factory because
> there
> is no formal support for Factory/Tumbleweed.

Alright, thanks Charles!
Comment 12 Gianluca Gabrielli 2022-01-20 10:39:26 UTC
UPDATES IN VERSION 2
====================

Include IOMMU aspect. Reword SILO mitigation.

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

To address XSA-380, reference counting was introduced for grant
mappings for the case where a PV guest would have the IOMMU enabled. PV
guests can request two forms of mappings.  When both are in use for any
individual mapping, unmapping of such a mapping can be requested in two
steps.  The reference count for such a mapping would then mistakenly be
decremented twice.  Underflow of the counters gets detected, resulting
in the triggering of a hypervisor bug check.

IMPACT
======

Malicious guest kernels may be able to mount a Denial of Service (DoS)
attack affecting the entire system.

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

All Xen versions from at least 3.2 onwards are vulnerable in principle,
if they have the XSA-380 fixes applied.

Only x86 systems are vulnerable.  Arm systems are not vulnerable.

Only x86 PV guests with access to PCI devices can leverage the
vulnerability.  x86 HVM and PVH guests, as well as PV guests without
access to PCI devices, cannot leverage the vulnerability.

Additionally from Xen 4.13 onwards x86 PV guests can leverage this
vulnerability only when being granted access to pages owned by another
domain.

MITIGATION
==========

Not running PV guests will avoid the vulnerability.

For Xen 4.12 and older not passing through PCI devices to PV guests will
avoid the vulnerability.

For Xen 4.13 and newer not enabling PCI device pass-through for PV
guests will avoid the vulnerability.  This can be achieved via omitting
any "passthrough=..." and "pci=..." settings from xl guest configuration
files, or by setting "passthrough=disabled" there.

- From Xen 4.13 onwards, XSM SILO can be available as a security policy
designed to permit guests to only be able to communicate with Dom0.
Dom0 does not normally offer its pages for guests to map, which means
the use of SILO mode normally mitigates the vulnerability.
Comment 15 Gianluca Gabrielli 2022-01-25 12:11:32 UTC
Public: https://xenbits.xen.org/xsa/advisory-394.html
Comment 16 Thomas Leroy 2022-01-25 14:14:06 UTC
SUSE:SLE-15-SP4:Update is also affected.
Comment 20 Swamp Workflow Management 2022-02-04 14:18:47 UTC
SUSE-SU-2022:0333-1: An update that fixes three vulnerabilities is now available.

Category: security (important)
Bug References: 1194576,1194581,1194588
CVE References: CVE-2022-23033,CVE-2022-23034,CVE-2022-23035
JIRA References: 
Sources used:
SUSE Linux Enterprise Module for Server Applications 15-SP3 (src):    xen-4.14.3_06-150300.3.18.2
SUSE Linux Enterprise Module for Basesystem 15-SP3 (src):    xen-4.14.3_06-150300.3.18.2
SUSE Linux Enterprise Micro 5.1 (src):    xen-4.14.3_06-150300.3.18.2

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 21 Swamp Workflow Management 2022-02-04 14:25:21 UTC
openSUSE-SU-2022:0333-1: An update that fixes three vulnerabilities is now available.

Category: security (important)
Bug References: 1194576,1194581,1194588
CVE References: CVE-2022-23033,CVE-2022-23034,CVE-2022-23035
JIRA References: 
Sources used:
openSUSE Leap 15.3 (src):    xen-4.14.3_06-150300.3.18.2
Comment 22 Swamp Workflow Management 2022-02-04 14:32:09 UTC
SUSE-SU-2022:0332-1: An update that fixes two vulnerabilities is now available.

Category: security (important)
Bug References: 1194581,1194588
CVE References: CVE-2022-23034,CVE-2022-23035
JIRA References: 
Sources used:
SUSE Linux Enterprise Server for SAP 15 (src):    xen-4.10.4_32-3.71.1
SUSE Linux Enterprise High Performance Computing 15-LTSS (src):    xen-4.10.4_32-3.71.1
SUSE Linux Enterprise High Performance Computing 15-ESPOS (src):    xen-4.10.4_32-3.71.1

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 23 Swamp Workflow Management 2022-02-04 14:32:47 UTC
SUSE-SU-2022:0331-1: An update that fixes two vulnerabilities is now available.

Category: security (important)
Bug References: 1194581,1194588
CVE References: CVE-2022-23034,CVE-2022-23035
JIRA References: 
Sources used:
SUSE OpenStack Cloud Crowbar 9 (src):    xen-4.11.4_26-2.68.1
SUSE OpenStack Cloud 9 (src):    xen-4.11.4_26-2.68.1
SUSE Linux Enterprise Server for SAP 12-SP4 (src):    xen-4.11.4_26-2.68.1
SUSE Linux Enterprise Server 12-SP4-LTSS (src):    xen-4.11.4_26-2.68.1

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 24 Swamp Workflow Management 2022-02-07 17:18:37 UTC
SUSE-SU-2022:0342-1: An update that fixes two vulnerabilities is now available.

Category: security (important)
Bug References: 1194581,1194588
CVE References: CVE-2022-23034,CVE-2022-23035
JIRA References: 
Sources used:
SUSE Linux Enterprise Server 12-SP2-BCL (src):    xen-4.7.6_20-43.85.1

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 25 Swamp Workflow Management 2022-02-09 20:20:20 UTC
SUSE-SU-2022:0359-1: An update that fixes two vulnerabilities is now available.

Category: security (important)
Bug References: 1194581,1194588
CVE References: CVE-2022-23034,CVE-2022-23035
JIRA References: 
Sources used:
SUSE OpenStack Cloud Crowbar 8 (src):    xen-4.9.4_26-3.100.1
SUSE OpenStack Cloud 8 (src):    xen-4.9.4_26-3.100.1
SUSE Linux Enterprise Server for SAP 12-SP3 (src):    xen-4.9.4_26-3.100.1
SUSE Linux Enterprise Server 12-SP3-LTSS (src):    xen-4.9.4_26-3.100.1
SUSE Linux Enterprise Server 12-SP3-BCL (src):    xen-4.9.4_26-3.100.1
HPE Helion Openstack 8 (src):    xen-4.9.4_26-3.100.1

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 26 Swamp Workflow Management 2022-02-17 14:19:40 UTC
SUSE-SU-2022:0467-1: An update that fixes three vulnerabilities is now available.

Category: security (important)
Bug References: 1194576,1194581,1194588
CVE References: CVE-2022-23033,CVE-2022-23034,CVE-2022-23035
JIRA References: 
Sources used:
SUSE Manager Server 4.1 (src):    xen-4.13.4_04-3.43.2
SUSE Manager Retail Branch Server 4.1 (src):    xen-4.13.4_04-3.43.2
SUSE Manager Proxy 4.1 (src):    xen-4.13.4_04-3.43.2
SUSE Linux Enterprise Server for SAP 15-SP2 (src):    xen-4.13.4_04-3.43.2
SUSE Linux Enterprise Server 15-SP2-LTSS (src):    xen-4.13.4_04-3.43.2
SUSE Linux Enterprise Server 15-SP2-BCL (src):    xen-4.13.4_04-3.43.2
SUSE Linux Enterprise Realtime Extension 15-SP2 (src):    xen-4.13.4_04-3.43.2
SUSE Linux Enterprise Micro 5.0 (src):    xen-4.13.4_04-3.43.2
SUSE Linux Enterprise High Performance Computing 15-SP2-LTSS (src):    xen-4.13.4_04-3.43.2
SUSE Linux Enterprise High Performance Computing 15-SP2-ESPOS (src):    xen-4.13.4_04-3.43.2
SUSE Enterprise Storage 7 (src):    xen-4.13.4_04-3.43.2

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 27 Swamp Workflow Management 2022-02-17 14:21:30 UTC
SUSE-SU-2022:14886-1: An update that fixes two vulnerabilities is now available.

Category: security (important)
Bug References: 1194581,1194588
CVE References: CVE-2022-23034,CVE-2022-23035
JIRA References: 
Sources used:
SUSE Linux Enterprise Server 11-SP4-LTSS (src):    xen-4.4.4_52-61.70.1
SUSE Linux Enterprise Debuginfo 11-SP4 (src):    xen-4.4.4_52-61.70.1

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 28 Swamp Workflow Management 2022-02-17 14:23:14 UTC
SUSE-SU-2022:0469-1: An update that fixes three vulnerabilities is now available.

Category: security (important)
Bug References: 1194576,1194581,1194588
CVE References: CVE-2022-23033,CVE-2022-23034,CVE-2022-23035
JIRA References: 
Sources used:
SUSE Linux Enterprise Software Development Kit 12-SP5 (src):    xen-4.12.4_18-3.58.2
SUSE Linux Enterprise Server 12-SP5 (src):    xen-4.12.4_18-3.58.2

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 29 Swamp Workflow Management 2022-02-17 14:26:25 UTC
SUSE-SU-2022:0468-1: An update that fixes three vulnerabilities is now available.

Category: security (important)
Bug References: 1194576,1194581,1194588
CVE References: CVE-2022-23033,CVE-2022-23034,CVE-2022-23035
JIRA References: 
Sources used:
SUSE Linux Enterprise Server for SAP 15-SP1 (src):    xen-4.12.4_18-3.60.2
SUSE Linux Enterprise Server 15-SP1-LTSS (src):    xen-4.12.4_18-3.60.2
SUSE Linux Enterprise Server 15-SP1-BCL (src):    xen-4.12.4_18-3.60.2
SUSE Linux Enterprise High Performance Computing 15-SP1-LTSS (src):    xen-4.12.4_18-3.60.2
SUSE Linux Enterprise High Performance Computing 15-SP1-ESPOS (src):    xen-4.12.4_18-3.60.2
SUSE Enterprise Storage 6 (src):    xen-4.12.4_18-3.60.2
SUSE CaaS Platform 4.0 (src):    xen-4.12.4_18-3.60.2

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.