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

RHSA-2018:0020 - 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 6.2 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 6.2 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 6.2

SRPM
kernel-2.6.32-220.76.2.el6.src.rpm SHA-256: fbdeaa5fb2674e22baea856898ca523dd69c0e75cc50664dcbb9b57019f67096
x86_64
kernel-2.6.32-220.76.2.el6.x86_64.rpm SHA-256: 5e468876d431495a7bd5aae0d53bed30b68805f28b20dbca6f9bab33edee9acc
kernel-debug-2.6.32-220.76.2.el6.x86_64.rpm SHA-256: 47d7f58811358e6f6dfc165e7b5ec95128c74258e1c28100cff6ca1b5e82b2e5
kernel-debug-debuginfo-2.6.32-220.76.2.el6.x86_64.rpm SHA-256: 4fc8333b818c9ac14c4a9b7d4456ad877eebb1ae990afb554ca2d07ff5b4faf9
kernel-debug-debuginfo-2.6.32-220.76.2.el6.x86_64.rpm SHA-256: 4fc8333b818c9ac14c4a9b7d4456ad877eebb1ae990afb554ca2d07ff5b4faf9
kernel-debug-devel-2.6.32-220.76.2.el6.x86_64.rpm SHA-256: 359e0c6756fc6776ca1d68e812834c2a363911c3558b5e0988010e968e23a966
kernel-debuginfo-2.6.32-220.76.2.el6.x86_64.rpm SHA-256: 4417a89dcdffa3dd1702d3fd0783b36d3f3e9706cbfc33f9e55fe522806b8c3a
kernel-debuginfo-2.6.32-220.76.2.el6.x86_64.rpm SHA-256: 4417a89dcdffa3dd1702d3fd0783b36d3f3e9706cbfc33f9e55fe522806b8c3a
kernel-debuginfo-common-x86_64-2.6.32-220.76.2.el6.x86_64.rpm SHA-256: e9fe6035be21d1738545fdf64e6cca06fc67fcfdad7245e1506ba3a014b3779f
kernel-debuginfo-common-x86_64-2.6.32-220.76.2.el6.x86_64.rpm SHA-256: e9fe6035be21d1738545fdf64e6cca06fc67fcfdad7245e1506ba3a014b3779f
kernel-devel-2.6.32-220.76.2.el6.x86_64.rpm SHA-256: dabe86d9e78c5e314ee4b77075da0200ab706a8747768ad1d5faeacf72301065
kernel-doc-2.6.32-220.76.2.el6.noarch.rpm SHA-256: 85dce6573ad4bc2a7e75d1ed053ada7f6e42025eb71a7dace05b1a5e9c497431
kernel-firmware-2.6.32-220.76.2.el6.noarch.rpm SHA-256: 716856bf5e77dac3927fa2bfcf0d281de22db74d25dad56fe46bdea26732d51d
kernel-headers-2.6.32-220.76.2.el6.x86_64.rpm SHA-256: 7985b44d840b9252c4235d6840bc2c7eedad17ce5a1508a6f81a7b1ceea56f25
perf-2.6.32-220.76.2.el6.x86_64.rpm SHA-256: 22681eb58200f7b233d860905d673ac7d4a426056be0140bcc68f9c2014fff9b
perf-debuginfo-2.6.32-220.76.2.el6.x86_64.rpm SHA-256: 7240f77846cca423232f8b1f292b7049a0924c6c081a64fdfecd15ea99c4a368
perf-debuginfo-2.6.32-220.76.2.el6.x86_64.rpm SHA-256: 7240f77846cca423232f8b1f292b7049a0924c6c081a64fdfecd15ea99c4a368
python-perf-2.6.32-220.76.2.el6.x86_64.rpm SHA-256: 3a12136a679f4fedb7bf123f6075fa12db12b0c2c0a5370782303615ad79158a
python-perf-debuginfo-2.6.32-220.76.2.el6.x86_64.rpm SHA-256: 6a451dd31456fa6fde130fbca6f88fb46e1a3bb967a9511eb08f37a807b30c3d
python-perf-debuginfo-2.6.32-220.76.2.el6.x86_64.rpm SHA-256: 6a451dd31456fa6fde130fbca6f88fb46e1a3bb967a9511eb08f37a807b30c3d

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