(RHSA-2018:2060) Important: qemu-kvm-rhev security and bug fix update

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)