RHSA-2018:0496 - Security Advisory

Topic

An update for kernel is now available for Red Hat Enterprise Linux 6.7 Extended Update Support.

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):

• hw: cpu: speculative execution branch target injection (s390-only) (CVE-2017-5715, Important)
• hw: cpu: speculative execution bounds-check bypass (s390 and powerpc) (CVE-2017-5753, Important)
• hw: cpu: speculative execution permission faults handling (powerpc-only) (CVE-2017-5754)

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

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#1538587)
• The Return Trampoline (Retpoline) mechanism mitigates the branch target injection, also known as the Spectre variant 2 vulnerability. With this update, Retpoline has been implemented into the Red Hat Enterprise Linux kernel. (BZ#1543023)

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

Users of kernel are advised to upgrade to these updated packages, which fix these bugs. The system must be rebooted for this update to take effect.

Affected Products

• Red Hat Enterprise Linux for x86_64 - Extended Update Support 6.7 x86_64
• Red Hat Enterprise Linux for x86_64 - Extended Update Support 6.7 i386
• Red Hat Enterprise Linux for IBM z Systems - Extended Update Support 6.7 s390x
• Red Hat Enterprise Linux for Power, big endian - Extended Update Support 6.7 ppc64
• Red Hat Enterprise Linux EUS Compute Node 6.7 x86_64
• Red Hat Enterprise Linux for SAP Solutions for x86_64 - Extended Update Support 6.7 x86_64

Fixes

• BZ - 1519778 - CVE-2017-5753 hw: cpu: speculative execution bounds-check bypass
• BZ - 1519780 - CVE-2017-5715 hw: cpu: speculative execution branch target injection
• BZ - 1519781 - CVE-2017-5754 hw: cpu: speculative execution permission faults handling

CVEs

• CVE-2017-5753

References

• https://access.redhat.com/security/updates/classification/#important