Issued:
2018-01-04
Updated:
2018-01-04

RHSA-2018:0018 - Security Advisory

Synopsis

Important: kernel security update

Type/Severity

Security Advisory: Important

Topic

An update for kernel is now available for Red Hat Enterprise Linux 6.4 Advanced 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):

An industry-wide issue was found in the way many modern microprocessor designs have implemented speculative execution of instructions (a commonly used performance optimization). There are three primary variants of the issue which differ in the way the speculative execution can be exploited.

Note: This issue is present in hardware and cannot be fully fixed via software update. The updated kernel packages provide software mitigation for this hardware issue at a cost of potential performance penalty. Please refer to References section for further information about this issue and the performance impact.

In this update mitigations for x86-64 architecture are provided.

Variant CVE-2017-5753 triggers the speculative execution by performing a bounds-check bypass. It relies on the presence of a precisely-defined instruction sequence in the privileged code as well as the fact that memory accesses may cause allocation 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 cross the syscall boundary and read privileged memory by conducting targeted cache side-channel attacks. (CVE-2017-5753, Important)

Variant CVE-2017-5715 triggers the speculative execution by utilizing branch target injection. It relies on the presence of a precisely-defined instruction sequence in the privileged code as well as the fact that memory accesses may cause allocation 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 cross the syscall and guest/host boundaries and read privileged memory by conducting targeted cache side-channel attacks. (CVE-2017-5715, Important)

Variant CVE-2017-5754 relies on the fact that, on impacted microprocessors, during speculative execution of instruction permission faults, exception generation triggered by a faulting access is suppressed until the retirement of the whole instruction block. In a combination with the fact that memory accesses may populate the cache even when the block is being dropped and never committed (executed), an unprivileged local attacker could use this flaw to read privileged (kernel space) memory by conducting targeted cache side-channel attacks. (CVE-2017-5754, Important)

Note: CVE-2017-5754 affects Intel x86-64 microprocessors. AMD x86-64 microprocessors are not affected by this issue.

Red Hat would like to thank Google Project Zero for reporting these issues.

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 6.4 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

(none)

References

Red Hat Enterprise Linux Server - AUS 6.4

SRPM
kernel-2.6.32-358.84.2.el6.src.rpm SHA-256: 3fb84960a60c556163ce7f0613f9f28db8c963737542f73f08afa5d1b7729ef4
x86_64
kernel-2.6.32-358.84.2.el6.x86_64.rpm SHA-256: c0f63609ebac6eb6373ea18d004c13de423ae88fb6deb6f8f9f600a7060e41a8
kernel-debug-2.6.32-358.84.2.el6.x86_64.rpm SHA-256: cddea226d1604d5eb4a44d8dd5d87ab63a7aa50ad91407e677e4884965291463
kernel-debug-debuginfo-2.6.32-358.84.2.el6.x86_64.rpm SHA-256: 47ceb9d0520d32403cca3a0f7931850bac73dd2e0132e048466ad1297059ce8e
kernel-debug-debuginfo-2.6.32-358.84.2.el6.x86_64.rpm SHA-256: 47ceb9d0520d32403cca3a0f7931850bac73dd2e0132e048466ad1297059ce8e
kernel-debug-devel-2.6.32-358.84.2.el6.x86_64.rpm SHA-256: 76b633e9f3af8c2afe09ce63d3ff7eaee5f5e7549cf5067636ac2f4235fb2f8b
kernel-debuginfo-2.6.32-358.84.2.el6.x86_64.rpm SHA-256: e33e92120ce83b1465d3d225c6e02bbf3fd147ce6bad2fdba1e412c26b244a82
kernel-debuginfo-2.6.32-358.84.2.el6.x86_64.rpm SHA-256: e33e92120ce83b1465d3d225c6e02bbf3fd147ce6bad2fdba1e412c26b244a82
kernel-debuginfo-common-x86_64-2.6.32-358.84.2.el6.x86_64.rpm SHA-256: 9bee6a79a944730660d888c079ad8f6b9645fc587fd8220708f866131dc84a77
kernel-debuginfo-common-x86_64-2.6.32-358.84.2.el6.x86_64.rpm SHA-256: 9bee6a79a944730660d888c079ad8f6b9645fc587fd8220708f866131dc84a77
kernel-devel-2.6.32-358.84.2.el6.x86_64.rpm SHA-256: c01f44a7e3106e14f1f86965c5de5ef7179e28d0491b989d73f829c851199d5d
kernel-doc-2.6.32-358.84.2.el6.noarch.rpm SHA-256: a2cd22462231e503df131f2206ea52d4b2741502ffc3cf634c3b37138f1a2c23
kernel-firmware-2.6.32-358.84.2.el6.noarch.rpm SHA-256: 5f3b7a6bdd1a7d0c3b601a34ca823ccb5cad24b9293d5a9e65fb2c97e272f456
kernel-headers-2.6.32-358.84.2.el6.x86_64.rpm SHA-256: b1ea44b5a4e2337aeba1ba604af86022f50a2ea7959d1583b9e2614b47db9dd6
perf-2.6.32-358.84.2.el6.x86_64.rpm SHA-256: 730ce7958e4b6d2201909bece7c0d4a7e22471acb8aabc61939a24e8fad62ff4
perf-debuginfo-2.6.32-358.84.2.el6.x86_64.rpm SHA-256: 122a05c3a278ac004afce3741ca48ffa32459c00e3a017b059560d39ba3acd4a
perf-debuginfo-2.6.32-358.84.2.el6.x86_64.rpm SHA-256: 122a05c3a278ac004afce3741ca48ffa32459c00e3a017b059560d39ba3acd4a
python-perf-2.6.32-358.84.2.el6.x86_64.rpm SHA-256: c354d07e67b9207fee316389b179beb7983387e221a90b9000f04e329f1b3413
python-perf-debuginfo-2.6.32-358.84.2.el6.x86_64.rpm SHA-256: 42acecadcad371c374f6cba07ee3a7d144aaf7bd571f8fc833faa2c276d7c6e2
python-perf-debuginfo-2.6.32-358.84.2.el6.x86_64.rpm SHA-256: 42acecadcad371c374f6cba07ee3a7d144aaf7bd571f8fc833faa2c276d7c6e2

The Red Hat security contact is secalert@redhat.com. More contact details at https://access.redhat.com/security/team/contact/.