Bug 1006298 (CVE-2013-4329)

Summary: CVE-2013-4329 xen: libxl partially sets up HVM passthrough even with disabled iommu
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, jforbes, jkurik, kraxel, m.a.young, mrezanin, pbonzini, rkrcmar, virt-maint, xen-maint
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: 2013-09-10 12:08:05 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: 1006301    
Bug Blocks: 1006302    

Description Petr Matousek 2013-09-10 12:06:44 UTC 
With HVM domains, libxl's setup of PCI passthrough devices does the IOMMU setup after giving (via the device model) the guest access to the hardware and advertising it to the guest.

If the IOMMU is disabled the overall setup fails, but after the device has been made available to the guest; subsequent DMA instructions from the guest to the device will cause wild DMA.

A HVM domain, given access to a device which bus mastering capable in the absence of a functioning IOMMU, can mount a privilege escalation or denial of service attack affecting the whole system.

References:

http://lists.xen.org/archives/html/xen-announce/2013-09/msg00001.html

Acknowledgements:

Red Hat would like to thank the Xen project for reporting this issue.
Comment 1 Petr Matousek 2013-09-10 12:08:05 UTC 
Statement:

Not vulnerable.

This issue does not affect the versions of the xen package as shipped with Red Hat Enterprise Linux 5 as it does not provide support for the libxl toolstack.

This issue does not affect Red Hat Enterprise Linux 6 and Red Hat Enterprise MRG 2.
Comment 2 Petr Matousek 2013-09-10 12:09:14 UTC 
Created xen tracking bugs for this issue:

Affects: fedora-all [bug 1006301]
Comment 3 Petr Matousek 2013-09-10 17:24:06 UTC 
Adding CVE as per:

  http://seclists.org/oss-sec/2013/q3/579