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|| ||Security ERRATA Important: qemu-kvm on SL6.x x86_64 |
|| ||Wed, 25 Jan 2012 15:20:53 -0600|
|| ||Article, Thread
Synopsis: Important: qemu-kvm security, bug fix, and enhancement update
Issue Date: 2012-01-23
CVE Numbers: CVE-2012-0029
KVM (Kernel-based Virtual Machine) is a full virtualization solution for
Linux on AMD64 and Intel 64 systems. qemu-kvm is the user-space component
for running virtual machines using KVM.
A heap overflow flaw was found in the way QEMU-KVM emulated the e1000
network interface card. A privileged guest user in a virtual machine whose
network interface is configured to use the e1000 emulated driver could use
this flaw to crash the host or, possibly, escalate their privileges on the
This update also fixes the following bug:
* qemu-kvm has a "scsi" option, to be used, for example, with the
"-device" option: "-device virtio-blk-pci,drive=[drive name],scsi=off".
Previously, however, it only masked the feature bit, and did not reject
SCSI commands if a malicious guest ignored the feature bit and issued a
request. This update corrects this issue. The "scsi=off" option can be
used to mitigate the virtualization aspect of CVE-2011-4127 before the
2.6.32-220.2.1.el6 kernel update is installed on the host.
This mitigation is only required if you do not have the 2.6.32-220.2.1.el6
kernel update installed on the host and you are using raw format virtio
disks backed by a partition or LVM volume.
If you run guests by invoking /usr/libexec/qemu-kvm directly, use the
"-global virtio-blk-pci.scsi=off" option to apply the mitigation. If you
are using libvirt, as recommended, and have libvirt-0.9.4-23.el6_2.4
installed, no manual action is required: guests will automatically use "scsi=off".
The libvirt-0.9.4-23.el6_2.4 package is a SL6 fastbug for 6.2 which is not yet released.
Note: After installing the 2.6.32-220.2.1.el6 kernel update, SCSI requests
issued by guests via the SG_IO IOCTL will not be passed to the underlying
block device when using raw format virtio disks backed by a partition or
LVM volume, even if "scsi=on" is used.
As well, this update adds the following enhancement:
* Prior to this update, qemu-kvm was not built with RELRO or PIE support.
qemu-kvm is now built with full RELRO and PIE support as a security
All users of qemu-kvm should upgrade to these updated packages, which
correct these issues and add this enhancement. 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.
vgabios-0.6b-3.6.el6.noarch.rpm was added to 6.0 and 6.1 to resolve a dependency issue
- Scientific Linux Development Team
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