Synopsis
Important: kernel security and bug fix update
Type/Severity
Security Advisory: Important
Topic
An update for kernel is now available for Red Hat Enterprise Linux 7.2 Advanced Update Support, Red Hat Enterprise Linux 7.2 Telco Extended Update Support, and Red Hat Enterprise Linux 7.2 Update Services for SAP Solutions.
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
The kernel packages contain the Linux kernel, the core of any Linux operating system.
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, x86 AMD)
Red Hat would like to thank Ken Johnson (Microsoft Security Response Center) and Jann Horn (Google Project Zero) for reporting this issue.
Bug Fix(es):
- When switching from the indirect branch speculation (IBRS) feature to the retpolines feature, the IBRS state of some CPUs was sometimes not handled correctly. Consequently, some CPUs were left with the IBRS Model-Specific Register (MSR) bit set to 1, which could lead to performance issues. With this update, the underlying source code has been fixed to clear the IBRS MSR bits correctly, thus fixing the bug. (BZ#1586145)
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
The system must be rebooted for this update to take effect.
Affected Products
-
Red Hat Enterprise Linux Server - AUS 7.2 x86_64
-
Red Hat Enterprise Linux Server - TUS 7.2 x86_64
-
Red Hat Enterprise Linux Server - Update Services for SAP Solutions 7.2 x86_64
Fixes
- BZ - 1566890 - CVE-2018-3639 hw: cpu: speculative store bypass
CVEs
References
Vulmon