Bug 1342529 (CVE-2016-5242, xsa181)

Summary: CVE-2016-5242 xsa181 xen: arm: Host crash caused by VMID exhaustion (XSA-181)
Product: [Other] Security Response Reporter: Adam Mariš <amaris>
Component: vulnerabilityAssignee: Red Hat Product Security <security-response-team>
Status: CLOSED NOTABUG QA Contact:
Severity: medium Docs Contact:
Priority: medium    
Version: unspecifiedCC: ailan, drjones, imammedo, knoel, m.a.young, mrezanin, pbonzini, rkrcmar, virt-maint, vkuznets, xen-maint
Target Milestone: ---Keywords: Security
Target Release: ---   
Hardware: All   
OS: Linux   
Fixed In Version: Doc Type: If docs needed, set a value
Doc Text:
Story Points: ---
Clone Of: Environment:
Last Closed: 2016-06-03 12:29:32 UTC Type: ---
Regression: --- Mount Type: ---
Documentation: --- CRM:
Verified Versions: Category: ---
oVirt Team: --- RHEL 7.3 requirements from Atomic Host:
Cloudforms Team: --- Target Upstream Version:
Bug Depends On: 1342530    
Bug Blocks:    

Description Adam Mariš 2016-06-03 12:27:22 UTC

VMIDs are a finite hardware resource, and allocated as part of domain
creation.  If no free VMIDs are available when trying to create a new domain,
a bug in the error path causes a NULL pointer to be used, resulting in a Data
Abort and host crash.


Attempting to create too many concurrent domains causes a host crash rather
than a graceful error.  A malicious device driver domain can hold references
to domains, preventing its VMID being released.


Xen versions 4.4 and later are affected.  Older Xen versions are unaffected.

x86 systems are not affected.

Only arm systems with less-privileged device driver domains can expose this


There is no mitigation.  Not using driver domains reclassifies the problem,
but does not fix it.


The crash was discussed publicly on xen-devel, before it was appreciated
that there was a security problem.


This issue was discovered by Aaron Cornelius of DornerWorks.

External References:



Name: the Xen project
Upstream: Aaron Cornelius (DornerWorks)

Comment 1 Adam Mariš 2016-06-03 12:27:54 UTC
Created xen tracking bugs for this issue:

Affects: fedora-all [bug 1342530]

Comment 2 Fedora Update System 2016-06-17 15:57:28 UTC
xen-4.5.3-8.fc23 has been pushed to the Fedora 23 stable repository. If problems still persist, please make note of it in this bug report.

Comment 3 Fedora Update System 2016-06-18 18:44:07 UTC
xen-4.6.1-11.fc24 has been pushed to the Fedora 24 stable repository. If problems still persist, please make note of it in this bug report.