Important kernel security update: CVE-2018-3639 (x86 AMD) and other issues; new kernel 2.6.32-042stab132.1; Virtuozzo 6.0 Update 12 Hotfix 29 (6.0.12-3710)

Issue date: 2018-07-17

Applies to: Virtuozzo 6.0

Virtuozzo Advisory ID: VZA-2018-048

1. Overview

This update provides a new kernel 2.6.32-042stab132.1 for Virtuozzo 6.0 that is a rebase to the Red Hat Enterprise Linux 6.10 kernel 2.6.32-754.2.1.el6. The new kernel introduces security fixes.

2. Security Fixes

  • [Important] [x86 AMD] 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)

  • [Moderate] By mmap()ing a FUSE-backed file onto a process’s memory containing command line arguments (or environment strings), an attacker can cause utilities from psutils or procps (such as ps, w) or any other program which makes a read() call to the /proc//cmdline (or /proc//environ) files to block indefinitely (denial of service) or for some controlled time (as a synchronization primitive for other attacks). (CVE-2018-1120)

  • [Moderate] A Floating Point Unit (FPU) state information leakage flaw was found in the way the Linux kernel saved and restored the FPU state during task switch. Linux kernels that follow the ‘Lazy FPU Restore’ scheme are vulnerable to the FPU state information leakage issue. An unprivileged local attacker could use this flaw to read FPU state bits by conducting targeted cache side-channel attacks, similar to the Meltdown vulnerability disclosed earlier this year. (CVE-2018-3665)

  • [Moderate] A flaw was found in the way the Linux kernel handled exceptions delivered after a stack switch operation via Mov SS or Pop SS instructions. During the stack switch operation, processor does not deliver interrupts and exceptions, they are delivered once the first instruction after the stack switch is executed. An unprivileged system user could use this flaw to crash the system kernel resulting in DoS. This CVE-2018-10872 was assigned due to regression of CVE-2018-8897. (CVE-2018-10872)

3. Installing the Update

Install the update by running ‘yum update’.