Topic

An update for qemu-kvm-rhev is now available for Red Hat Virtualization 4 for Red Hat Enterprise Linux 7.

Red Hat Product Security has rated this update as having a security impact of Important. A Common Vulnerability Scoring System (CVSS) base score, which gives a detailed severity rating, is available for each vulnerability from the CVE link(s) in the References section.

Description

KVM (Kernel-based Virtual Machine) is a full virtualization solution for Linux on a variety of architectures. The qemu-kvm-rhev packages provide the user-space component for running virtual machines that use KVM in environments managed by Red Hat products.

Security Fix(es):

• An industry-wide issue was found in the way many modern microprocessor designs have implemented speculative execution of Load & Store instructions (a commonly used performance optimization). It relies on the presence of a precisely-defined instruction sequence in the privileged code as well as the fact that memory read from address to which a recent memory write has occurred may see an older value and subsequently cause an update into the microprocessor's data cache even for speculatively executed instructions that never actually commit (retire). As a result, an unprivileged attacker could use this flaw to read privileged memory by conducting targeted cache side-channel attacks. (CVE-2018-3639)

Red Hat would like to thank Ken Johnson (Microsoft Security Response Center) and Jann Horn (Google Project Zero) for reporting this issue.

Note: This is the qemu-kvm-rhev side of the CVE-2018-3639 mitigation that includes support for guests running on hosts with AMD processors.

Bug Fix(es):

• Previously, using device passthrough for a SCSI-2 device failed and returned an "Illegal Request" error. With this update, the QEMU emulator checks the SCSI version of the device when performing passthrough. As a result, the described problem no longer occurs. (BZ#1571370)
• Under certain circumstances, resuming a paused guest generated redundant "VIR_DOMAIN_PAUSED_UNKNOWN" error messages in the libvirt log. This update corrects the event sending order when resuming guests, which prevents the errors being logged. (BZ#1582122)

Enhancement(s):

• With this update, Ceph storage is supported by KVM virtualization on all CPU architectures supported by Red Hat. (BZ#1588001)

Solution

For details on how to apply this update, which includes the changes described in this advisory, refer to:

https://access.redhat.com/articles/11258

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.

Affected Products

• Red Hat Virtualization 4 for RHEL 7 x86_64
• Red Hat Virtualization for IBM Power LE 4 for RHEL 7 ppc64le

Fixes

• BZ - 1566890 - CVE-2018-3639 hw: cpu: speculative store bypass
• BZ - 1582122 - IOERROR pause code lost after resuming a VM while I/O error is still present [rhel-7.5.z]
• BZ - 1588001 - Enable Native Ceph support on non x86_64 CPUs [rhel-7.5.z]

CVEs

• CVE-2018-3639

References

• https://access.redhat.com/security/updates/classification/#important
• https://access.redhat.com/security/vulnerabilities/ssbd