Bug 1877382 (CVE-2020-25604) - CVE-2020-25604 xen: race when migrating timers between x86 HVM vCPU-s (XSA-336)
Summary: CVE-2020-25604 xen: race when migrating timers between x86 HVM vCPU-s (XSA-336)
Keywords:
Status: CLOSED WONTFIX
Alias: CVE-2020-25604
Product: Security Response
Classification: Other
Component: vulnerability
Version: unspecified
Hardware: All
OS: Linux
medium
medium
Target Milestone: ---
Assignee: Red Hat Product Security
QA Contact:
URL:
Whiteboard:
Depends On: 1881618
Blocks: 1877386
TreeView+ depends on / blocked
 
Reported: 2020-09-09 13:54 UTC by Guilherme de Almeida Suckevicz
Modified: 2021-02-16 19:17 UTC (History)
25 users (show)

Fixed In Version:
Doc Type: If docs needed, set a value
Doc Text:
A race condition flaw was found in Xen. When migrating timers of x86 HVM guests between its vCPUs, the locking model that is used allows for a second vCPU of the same guest that is also operating on the timers, to release a lock that was not acquired. The issue leads to the hypervisor hanging or crashing, resulting in a denial of service (DoS). The highest threat from this vulnerability is to system availability.
Clone Of:
Environment:
Last Closed: 2020-09-22 20:41:18 UTC
Embargoed:

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Description Guilherme de Almeida Suckevicz 2020-09-09 13:54:04 UTC 
When migrating timers of x86 HVM guests between its vCPU-s, the locking model used allows for a second vCPU of the same guest also operating on the timers to release a lock that it didn't acquire.
Comment 1 Guilherme de Almeida Suckevicz 2020-09-09 13:54:10 UTC 
Acknowledgments:

Name: the Xen project
Comment 2 Mauro Matteo Cascella 2020-09-15 16:09:14 UTC 
Statement:

Only x86 HVM guests with more than one vCPU can exploit this vulnerability. ARM systems as well as x86 PV and PVH guests are not affected by this flaw.

This flaw has been rated as having a security impact of Moderate, and is not currently planned to be addressed in future updates of Red Hat Enterprise Linux 5. Red Hat Enterprise Linux 5 is now in Extended Life Phase of the support and maintenance life cycle. For additional information, refer to the Red Hat Enterprise Linux Life Cycle: https://access.redhat.com/support/policy/updates/errata/.
Comment 3 Mauro Matteo Cascella 2020-09-15 16:12:10 UTC 
Mitigation:

There is no known mitigation for this flaw apart from applying the patch.
Comment 4 Mauro Matteo Cascella 2020-09-22 18:28:54 UTC 
Created xen tracking bugs for this issue:

Affects: fedora-all [bug 1881618]
Comment 5 Product Security DevOps Team 2020-09-22 20:41:18 UTC 
This bug is now closed. Further updates for individual products will be reflected on the CVE page(s):

https://access.redhat.com/security/cve/cve-2020-25604
Comment 6 Mauro Matteo Cascella 2020-09-23 07:35:03 UTC 
External References:

https://xenbits.xen.org/xsa/advisory-336.html
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