RHSA-2011:1850 - Security Advisory

Topic

An updated rhev-hypervisor6 package that fixes one security issue and two
bugs is now available.

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.

Description

The rhev-hypervisor6 package provides a Red Hat Enterprise Virtualization
Hypervisor ISO disk image. The Red Hat Enterprise Virtualization Hypervisor
is a dedicated Kernel-based Virtual Machine (KVM) hypervisor. It includes
everything necessary to run and manage virtual machines: A subset of the
Red Hat Enterprise Linux operating environment and the Red Hat Enterprise
Virtualization Agent.

Note: Red Hat Enterprise Virtualization Hypervisor is only available for
the Intel 64 and AMD64 architectures with virtualization extensions.

Using the SG_IO IOCTL to issue SCSI requests to partitions or LVM volumes
resulted in the requests being passed to the underlying block device. If a
privileged user only had access to a single partition or LVM volume, they
could use this flaw to bypass those restrictions and gain read and write
access (and be able to issue other SCSI commands) to the entire block
device.

In KVM (Kernel-based Virtual Machine) environments using raw format virtio
disks backed by a partition or LVM volume, a privileged guest user could
bypass intended restrictions and issue read and write requests (and other
SCSI commands) on the host, and possibly access the data of other guests
that reside on the same underlying block device. Refer to Red Hat Bugzilla
bug 752375 for further details and a mitigation script for users who cannot
apply this update immediately. (CVE-2011-4127)

This updated package provides updated components that include fixes for
various security issues. These issues have no security impact on Red Hat
Enterprise Virtualization Hypervisor itself, however. The security fixes
included in this update address the following CVE numbers:

CVE-2011-4539 (dhcp issue)

CVE-2011-4339 (ipmitool issue)

CVE-2011-1530 (krb5 issue)

This update also fixes the following bugs:

• Virtual LAN (VLAN) identifiers containing a space were accepted, even

though they could not be configured correctly. With this update, VLAN
identifiers containing a space are rejected with an "Invalid VLAN ID"
message. (BZ#761537)

• After configuring netconsole, it was not possible to start the service:

the "service netconsole start" command failed with a warning that
configfs.ko could not be found, and a fatal error that netconsole.ko could
not be inserted. With this update, the netconsole service starts as
expected. Note that after netconsole is configured, the service will not
automatically start, even after rebooting. The service must be manually
started. (BZ#765898)

Users of the Red Hat Enterprise Virtualization Hypervisor are advised to
upgrade to this updated package, which corrects these issues.

Solution

Before applying this update, make sure all previously-released errata
relevant to your system have been applied.

This update is available via the Red Hat Network. Details on how to
use the Red Hat Network to apply this update are available at
https://access.redhat.com/kb/docs/DOC-11259

Affected Products

• Red Hat Virtualization 6 x86_64

Fixes

• BZ - 752375 - CVE-2011-4127 kernel: possible privilege escalation via SG_IO ioctl
• BZ - 760333 - rhev-hypervisor6 6.2 update 1 release bugzilla
• BZ - 761537 - vlan id should not accept a space in it
• BZ - 765898 - netconsole does not work

CVEs

• CVE-2011-4127

References

• https://access.redhat.com/security/updates/classification/#important
• https://bugzilla.redhat.com/show_bug.cgi?id=752375