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

RHSA-2018:0021 - Security Advisory

Synopsis

Important: kernel-rt security update

Type/Severity

Security Advisory: Important

Topic

An update for kernel-rt is now available for Red Hat Enterprise MRG 2.

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-rt packages provide the Real Time Linux Kernel, which enables fine-tuning for systems with extremely high determinism requirements.

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

  • MRG Realtime 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

MRG Realtime 2

SRPM
kernel-rt-3.10.0-693.11.1.rt56.606.el6rt.src.rpm SHA-256: 616bc512a11b18f3656be61d0fbd3f4979f61f8b3ef7aa8cbc25092072436305
x86_64
kernel-rt-3.10.0-693.11.1.rt56.606.el6rt.x86_64.rpm SHA-256: 3873b93c206f9e4c42c41a5fd32fc5b91625b71d8c9be1d32c782fec5632c9c1
kernel-rt-debug-3.10.0-693.11.1.rt56.606.el6rt.x86_64.rpm SHA-256: e46c34043c7a434eb3effdd96af00b4ec9575e2c0f13ffc82252ac92a2f0be43
kernel-rt-debug-debuginfo-3.10.0-693.11.1.rt56.606.el6rt.x86_64.rpm SHA-256: ff3b81ec94706363b14334b8f59661713de321c9490089cd05e258c150589dd7
kernel-rt-debug-devel-3.10.0-693.11.1.rt56.606.el6rt.x86_64.rpm SHA-256: 6d6026eab24171e868e21d57b91a75b8ea5d1d968b8f240b5b35bf10d9054b3e
kernel-rt-debuginfo-3.10.0-693.11.1.rt56.606.el6rt.x86_64.rpm SHA-256: cd2601ae00c764a2e67b19daac3c9ea35426f1c0266fe691d5058c17cb775d12
kernel-rt-debuginfo-common-x86_64-3.10.0-693.11.1.rt56.606.el6rt.x86_64.rpm SHA-256: ff65c8f2c885125412636c524c17ba196b6ff84bf15d0a7eb5363c1d6c239ed0
kernel-rt-devel-3.10.0-693.11.1.rt56.606.el6rt.x86_64.rpm SHA-256: afd27324035df4555b402f8ffd39077fd9dde0bba733e92dbe732111d785a1f3
kernel-rt-doc-3.10.0-693.11.1.rt56.606.el6rt.noarch.rpm SHA-256: 5768ad6fbb94dfd89a3f51e5bb4664f4a5d992766efdb601dec5fd0e43e8582d
kernel-rt-firmware-3.10.0-693.11.1.rt56.606.el6rt.noarch.rpm SHA-256: 3ce5c209202b48104318ed989f965f3c2be3664f5773a056adc66bd317847146
kernel-rt-trace-3.10.0-693.11.1.rt56.606.el6rt.x86_64.rpm SHA-256: 7052e50d751d92718a9550a3654f1a58c476dfa095bab9a7172a40ecb5220551
kernel-rt-trace-debuginfo-3.10.0-693.11.1.rt56.606.el6rt.x86_64.rpm SHA-256: d8d3ea4a7f71e5b8e008382381ce65b015b4da63f9b34f58ee059b997fad989c
kernel-rt-trace-devel-3.10.0-693.11.1.rt56.606.el6rt.x86_64.rpm SHA-256: b64c365b2d626cf93693e32a9e4d47a940477f46853b3ac829bae698790598b2
kernel-rt-vanilla-3.10.0-693.11.1.rt56.606.el6rt.x86_64.rpm SHA-256: 42011da4a32e53882edb36e731249111feedfd44fe1e001e280899fa85b797d6
kernel-rt-vanilla-debuginfo-3.10.0-693.11.1.rt56.606.el6rt.x86_64.rpm SHA-256: 1c064d8fe954885305e7ce78cdd4a06aa3465feff32bfd941342671b844b1d5d
kernel-rt-vanilla-devel-3.10.0-693.11.1.rt56.606.el6rt.x86_64.rpm SHA-256: f4de7877497704404f3e0807ad80ac5fea44a3d9b45626f08a7f2b2b312ea183

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