RHSA-2018:1351 - Security Advisory

Topic

An update for kernel is now available for Red Hat Enterprise Linux 6.6 Advanced Update Support and Red Hat Enterprise Linux 6.6 Telco Extended Update Support.

Red Hat Product Security has rated this update as having a security impact of Moderate. 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.

[Updated 10 May 2018]

The references to CVE-2017-5754 x86 (32-bit) mitigation were removed because Red Hat Enterprise Linux 6.6 Advanced Update Support and Red Hat Enterprise Linux 6.6 Telco Extended Update Support do not include support for x86 32-bit architecture. Consequently, impact rating of this erratum was changed from Important to Moderate.

Description

The kernel packages contain the Linux kernel, the core of any Linux operating system.

Security Fix(es):

• Kernel: error in exception handling leads to DoS (CVE-2018-8897)

For more details about the security issue(s), including the impact, a CVSS score, and other related information, refer to the CVE page(s) listed in the References section.

Red Hat would like to thank Nick Peterson (Everdox Tech LLC) and Andy Lutomirski for reporting this issue.

Bug Fix(es):

• If an NFSv3 client mounted a subdirectory of an exported file system, a directory entry to the mount hosting the export was incorrectly held even after clearing the cache. Consequently, attempts to unmount the subdirectory with the umount command failed with the EBUSY error. With this update, the underlying source code has been fixed, and the unmount operation now succeeds as expected in the described situation. (BZ#1538588)
• The kernel build requirements have been updated to the GNU Compiler Collection (GCC) compiler version that has the support for Retpolines. The Retpolines mechanism is a software construct that leverages specific knowledge of the underlying hardware to mitigate the branch target injection, also known as Spectre variant 2 vulnerability described in CVE-2017-5715. (BZ#1554254)

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 6.6 x86_64
• Red Hat Enterprise Linux Server - TUS 6.6 x86_64

Fixes

• BZ - 1567074 - CVE-2018-8897 Kernel: error in exception handling leads to DoS

CVEs

• CVE-2018-8897

References

• https://access.redhat.com/security/updates/classification/#moderate
• https://access.redhat.com/security/vulnerabilities/pop_ss