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Bug 547202 (CVE-2015-3340) - <app-emulation/xen-{4.2.5-r9,4.4.2-r2,4.5.0-r6}: Information leak through XEN_DOMCTL_gettscinfo (XSA-132) (CVE-2015-3340)
Summary: <app-emulation/xen-{4.2.5-r9,4.4.2-r2,4.5.0-r6}: Information leak through XEN...
Alias: CVE-2015-3340
Product: Gentoo Security
Classification: Unclassified
Component: Vulnerabilities (show other bugs)
Hardware: All Linux
: Normal normal (vote)
Assignee: Gentoo Security
Whiteboard: B4 [glsa cve]
Depends on:
Reported: 2015-04-20 17:30 UTC by Kristian Fiskerstrand (RETIRED)
Modified: 2016-04-05 07:00 UTC (History)
1 user (show)

See Also:
Package list:
Runtime testing required: ---


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Description Kristian Fiskerstrand (RETIRED) gentoo-dev 2015-04-20 17:30:23 UTC

The handler for XEN_DOMCTL_gettscinfo failed to initialize a padding
field subsequently copied to guest memory.

A similar leak existed in XEN_SYSCTL_getdomaininfolist, which is being
addressed here regardless of that operation being declared unsafe for
disaggregation by XSA-77.


Malicious or buggy stub domain kernels or tool stacks otherwise living
outside of Domain0 may be able to read sensitive data relating to the
hypervisor or other guests not under the control of that domain.


Xen 4.0.x and later are vulnerable.

Only x86 systems are vulnerable.  ARM systems are not vulnerable.

The vulnerability is only exposed to service domains with privilege over
another guest.  In a usual configuration that means only device model
emulators (qemu-dm) when these are running in a separate domain.

In the case of HVM guests whose device model is running in an
unrestricted dom0 process, qemu-dm already has the ability to cause
problems for the whole system.  So in that case the vulnerability is
not applicable.

This vulnerability is applicable for an HVM guest with a stub qemu-dm.
That is, where the device model runs in a separate domain (in the case
of xl, as requested by "device_model_stubdomain_override=1" in the xl
domain configuration file).  In this case a guest which has already
exploited another vulnerability, to gain control of the device model,
would be able to exercise the information leak.

However, the security of a system with qemu-dm running in a stub domain
is still better than with a qemu-dm running as an unrestricted dom0
process.  Therefore users with these configurations should not switch
to an unrestricted dom0 qemu-dm.

Finally, in a radically disaggregated system, where the service domain
software (probably, the device model domain image in the HVM case) is
not always supplied by the host administrator, a malicious service
domain administrator can exercise this vulnerability.


There is no mitigation available.

In a radically disaggregated system, restricting HVM service domains
to software images approved by the host administrator will avoid the
vulnerability (so long as there isn't also a vulnerability in the
service domain).


The fix for this bug was publicly posted on xen-devel, before it was
appreciated that there was a security problem.


This issue was recognized as security issue by Jan Beulich of SUSE.
Comment 1 Yixun Lan archtester gentoo-dev 2015-05-14 05:16:44 UTC
fixed in tree, thanks

Comment 2 Kristian Fiskerstrand (RETIRED) gentoo-dev 2015-05-14 19:20:43 UTC
request filed together with bug 549200
Comment 3 GLSAMaker/CVETool Bot gentoo-dev 2015-06-07 13:54:02 UTC
CVE-2015-3340 (
  Xen 4.2.x through 4.5.x does not initialize certain fields, which allows
  certain remote service domains to obtain sensitive information from memory
  via a (1) XEN_DOMCTL_gettscinfo or (2) XEN_SYSCTL_getdomaininfolist request.
Comment 4 GLSAMaker/CVETool Bot gentoo-dev 2016-04-05 07:00:05 UTC
This issue was resolved and addressed in
 GLSA 201604-03 at
by GLSA coordinator Yury German (BlueKnight).