Important kernel security update: New kernel 2.6.32-042stab138.1 for Virtuozzo Containers for Linux 4.7, Server Bare Metal 5.0

Issue date: 2019-05-16

Applies to: Virtuozzo Containers for Linux 4.7, Server Bare Metal 5.0

Virtuozzo Advisory ID: VZA-2019-036

1. Overview

This update provides a new kernel 2.6.32-042stab138.1 for Virtuozzo Containers for Linux 4.7 and Server Bare Metal 5.0 based on the RHEL 6.10 kernel 2.6.32-754.14.2.el6. The new kernel inherits security fixes for the Microarchitectural Store Buffer Data (MDS) vulnerability from the RHEL kernel.

2. Security Fixes

  • [Important] A flaw was found in the implementation of the ‘fill buffer’, a mechanism used by modern CPUs when a cache-miss is made on L1 CPU cache. If an attacker can generate a load operation that would create a page fault, the execution will continue speculatively with incorrect data from the fill buffer while the data is fetched from higher level caches. This response time can be measured to infer data in the fill buffer. (CVE-2018-12130)

  • [Moderate] Modern Intel microprocessors implement hardware-level micro-optimizations to improve the performance of writing data back to CPU caches. The write operation is split into STA (STore Address) and STD (STore Data) sub-operations. These sub-operations allow the processor to hand-off address generation logic into these sub-operations for optimized writes. Both of these sub-operations write to a shared distributed processor structure called the ‘processor store buffer’. As a result, an unprivileged attacker could use this flaw to read private data resident within the CPU’s processor store buffer. (CVE-2018-12126)

  • [Moderate] Microprocessors use a ‘load port’ subcomponent to perform load operations from memory or IO. During a load operation, the load port receives data from the memory or IO subsystem and then provides the data to the CPU registers and operations in the CPU’s pipelines. Stale load operations results are stored in the ‘load port’ table until overwritten by newer operations. Certain load-port operations triggered by an attacker can be used to reveal data about previous stale requests leaking data back to the attacker via a timing side-channel. (CVE-2018-12127)

  • [Moderate] Uncacheable memory on some microprocessors utilizing speculative execution may allow an authenticated user to potentially enable information disclosure via a side channel with local access. (CVE-2019-11091)

3. Installing the Update

The update is only available for customers subscribed to the Extended Lifecycle Support (ELS) program. Download and install the update using the vzup2date utility included in the distribution. Reboot the host to apply the update.