Bug 1035811 (CVE-2013-6400)

Summary: CVE-2013-6400 xen: IOMMU TLB flushing may be inadvertently suppressed
Product: [Other] Security Response Reporter: Petr Matousek <pmatouse>
Component: vulnerabilityAssignee: Red Hat Product Security <security-response-team>
Status: CLOSED NOTABUG QA Contact:
Severity: high Docs Contact:
Priority: high    
Version: unspecifiedCC: drjones, imammedo, pbonzini, rkrcmar, security-response-team
Target Milestone: ---Keywords: Security
Target Release: ---   
Hardware: All   
OS: Linux   
Whiteboard:
Fixed In Version: Doc Type: Bug Fix
Doc Text:
Story Points: ---
Clone Of: Environment:
Last Closed: 2013-11-28 14:28:53 UTC Type: ---
Regression: --- Mount Type: ---
Documentation: --- CRM:
Verified Versions: Category: ---
oVirt Team: --- RHEL 7.3 requirements from Atomic Host:
Cloudforms Team: --- Target Upstream Version:
Embargoed:
Bug Depends On: 1040024    
Bug Blocks: 1035806    

Description Petr Matousek 2013-11-28 14:26:21 UTC 
An internal flag is used to temporarily suppress IOMMU TLB flushes, in
order to consolidate multiple single page flushes into one wider
flush.  This flag is not cleared again, on certain error paths.  This
can result in TLB flushes not happening when they are needed.
Retaining stale TLB entries could allow guests access to memory that
ought to have been revoked, or grant greater access than intended.

Malicious guest administrators might be able to cause host-wide denial of
service, or escalate their privilege to that of the host.

Acknowledgements:

Red Hat would like to thank the Xen project for reporting this issue.
Comment 2 Petr Matousek 2013-11-28 14:28:53 UTC 
Statement:

Not vulnerable.

This issue did not affect the versions of the kernel-xen package as shipped with Red Hat Enterprise Linux 5.

This issue did not affect Red Hat Enterprise Linux 6 and Red Hat Enterprise MRG 2 as we did not have support for Xen hypervisor.
Comment 3 Petr Matousek 2013-12-10 14:25:21 UTC 
This is now public via:

  http://www.openwall.com/lists/oss-security/2013/12/10/7
Comment 4 Petr Matousek 2013-12-10 14:26:09 UTC 
Created xen tracking bugs for this issue:

Affects: fedora-all [bug 1040024]