Synopsis:          Important: kernel security update
Advisory ID:       SLSA-2018:0007-1
Issue Date:        2018-01-03
CVE Numbers:       CVE-2017-5753
                   CVE-2017-5715
                   CVE-2017-5754
--

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. The performance impact of these patches may vary considerably based on workload
and hardware configuration.

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.
--

SL7
  x86_64
    kernel-3.10.0-693.11.6.el7.x86_64.rpm
    kernel-debug-3.10.0-693.11.6.el7.x86_64.rpm
    kernel-debug-debuginfo-3.10.0-693.11.6.el7.x86_64.rpm
    kernel-debug-devel-3.10.0-693.11.6.el7.x86_64.rpm
    kernel-debuginfo-3.10.0-693.11.6.el7.x86_64.rpm
    kernel-debuginfo-common-x86_64-3.10.0-693.11.6.el7.x86_64.rpm
    kernel-devel-3.10.0-693.11.6.el7.x86_64.rpm
    kernel-headers-3.10.0-693.11.6.el7.x86_64.rpm
    kernel-tools-3.10.0-693.11.6.el7.x86_64.rpm
    kernel-tools-debuginfo-3.10.0-693.11.6.el7.x86_64.rpm
    kernel-tools-libs-3.10.0-693.11.6.el7.x86_64.rpm
    perf-3.10.0-693.11.6.el7.x86_64.rpm
    perf-debuginfo-3.10.0-693.11.6.el7.x86_64.rpm
    python-perf-3.10.0-693.11.6.el7.x86_64.rpm
    python-perf-debuginfo-3.10.0-693.11.6.el7.x86_64.rpm
    kernel-tools-libs-devel-3.10.0-693.11.6.el7.x86_64.rpm
  noarch
    kernel-abi-whitelists-3.10.0-693.11.6.el7.noarch.rpm
    kernel-doc-3.10.0-693.11.6.el7.noarch.rpm

- Scientific Linux Development Team