RHEL 6 : qemu-kvm-rhev (RHSA-2012:1233)

This script is Copyright (C) 2014-2017 Tenable Network Security, Inc.


Synopsis :

The remote Red Hat host is missing one or more security updates.

Description :

Updated qemu-kvm-rhev packages that fix one security issue and two
bugs are now available for Red Hat Enterprise Linux 6.

The Red Hat Security Response Team has rated this update as having
important security impact. A Common Vulnerability Scoring System
(CVSS) base score, which gives a detailed severity rating, is
available from the CVE link in the References section.

KVM (Kernel-based Virtual Machine) is a full virtualization solution
for Linux on AMD64 and Intel 64 systems. The qemu-kvm-rhev packages
form the user-space component for running virtual machines using KVM.

A flaw was found in the way QEMU handled VT100 terminal escape
sequences when emulating certain character devices. A guest user with
privileges to write to a character device that is emulated on the host
using a virtual console back-end could use this flaw to crash the
qemu-kvm process on the host or, possibly, escalate their privileges
on the host. (CVE-2012-3515)

When using qemu-kvm-rhev on a Red Hat Enterprise Linux 6 host not
managed by Red Hat Enterprise Virtualization :

* This flaw did not affect the default use of KVM. Affected
configurations were :

- When guests were started from the command line
('/usr/libexec/qemu-kvm') without the '-nodefaults'
option, and also without specifying a serial or parallel
device, or a virtio-console device, that specifically
does not use a virtual console (vc) back-end. (Note that
Red Hat does not support invoking 'qemu-kvm' from the
command line without '-nodefaults' on Red Hat Enterprise
Linux 6.)

- Guests that were managed via libvirt, such as when using
Virtual Machine Manager (virt-manager), but that have a
serial or parallel device, or a virtio-console device,
that uses a virtual console back-end. By default, guests
managed via libvirt will not use a virtual console
back-end for such devices.

When using qemu-kvm-rhev on a Red Hat Enterprise Virtualization
managed Red Hat Enterprise Linux 6 host :

* This flaw did not affect the default use of a Red Hat Enterprise
Virtualization host: it is not possible to add a device that uses a
virtual console back-end via Red Hat Enterprise Virtualization
Manager.

To specify a virtual console back-end for a device and therefore be
vulnerable to this issue, the device would have to be created another
way, for example, by using a VDSM hook.

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

This update also fixes the following bugs :

* Previously, the KVM modules were not loaded by the postinstall
scriptlet of RPM scripts. This bug caused various issues and required
the system to be rebooted to resolve them. With this update, the
modules are loaded properly by the scriptlet and no unnecessary
reboots are now required. (BZ#839897)

* Previously, when a guest was started up with two serial devices,
qemu-kvm returned an error message and terminated the boot because IRQ
4 for the ISA bus was being used by both devices. This update fixes
the qemu-kvm code, which allows IRQ 4 to be used by more than one
device on the ISA bus, and the boot now succeeds in the described
scenario. (BZ#840054)

All users of qemu-kvm-rhev are advised to upgrade to these updated
packages, which fix these issues. After installing this update, shut
down all running virtual machines. Once all virtual machines have shut
down, start them again for this update to take effect.

See also :

https://www.redhat.com/security/data/cve/CVE-2012-3515.html
http://rhn.redhat.com/errata/RHSA-2012-1233.html

Solution :

Update the affected packages.

Risk factor :

High / CVSS Base Score : 7.2
(CVSS2#AV:L/AC:L/Au:N/C:C/I:C/A:C)
CVSS Temporal Score : 6.3
(CVSS2#E:ND/RL:OF/RC:C)
Public Exploit Available : false

Family: Red Hat Local Security Checks

Nessus Plugin ID: 78932 ()

Bugtraq ID: 55413

CVE ID: CVE-2012-3515

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