Bug 1214035 (CVE-2015-3340, xsa132) - CVE-2015-3340 xen: information leak through XEN_DOMCTL_gettscinfo (xsa132)
Summary: CVE-2015-3340 xen: information leak through XEN_DOMCTL_gettscinfo (xsa132)
Alias: CVE-2015-3340, xsa132
Product: Security Response
Classification: Other
Component: vulnerability
Version: unspecified
Hardware: All
OS: Linux
Target Milestone: ---
Assignee: Red Hat Product Security
QA Contact:
Depends On: 1214037
TreeView+ depends on / blocked
Reported: 2015-04-21 19:44 UTC by Martin Prpič
Modified: 2023-05-12 16:31 UTC (History)
21 users (show)

Fixed In Version:
Doc Type: Bug Fix
Doc Text:
Clone Of:
Last Closed: 2015-04-21 19:52:16 UTC

Attachments (Terms of Use)

Description Martin Prpič 2015-04-21 19:44:20 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.


Applying the appropriate attached patch resolves this issue.

xsa132-unstable.patch xen-unstable, Xen 4.5.x, Xen 4.4.x, Xen 4.3.x
xsa132-4.2.patch Xen 4.2.x

$ sha256sum xsa132*.patch
3a28eb33c02360ec22c51824e469b1cf6be87941256d0b3aa34a5bd1d7735328 xsa132-4.2.patch
329d4edf1e1133795ece41f2fc8887c5f4cc06b42ced63c810c610b17bcee46d xsa132.patch

Comment 1 Martin Prpič 2015-04-21 19:45:50 UTC
Upstream patches:

xsa132-4.2.patch -- http://xenbits.xen.org/xsa/xsa132-4.2.patch
xsa132.patch     -- http://xenbits.xen.org/xsa/xsa132.patch

External References:


Comment 2 Martin Prpič 2015-04-21 19:46:38 UTC

Red Hat would like to thank the Xen project for reporting this issue.

Comment 3 Martin Prpič 2015-04-21 19:51:49 UTC
Created xen tracking bugs for this issue:

Affects: fedora-all [bug 1214037]

Comment 4 Martin Prpič 2015-04-21 19:52:16 UTC

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

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