[SECURITY] [DLA 1989-1] linux security update

Package : linux
Version : 3.16.76-1
CVE ID : CVE-2019-0154 CVE-2019-11135

Several vulnerabilities have been discovered in the Linux kernel that
may lead to a privilege escalation, denial of service, or information
leak.

CVE-2019-0154

Intel discovered that on their 8th and 9th generation GPUs,
reading certain registers while the GPU is in a low-power state
can cause a system hang.  A local user permitted to use the GPU
can use this for denial of service.

This update mitigates the issue through changes to the i915
driver.

The affected chips (gen8) are listed at
<https://en.wikipedia.org/wiki/List_of_Intel_graphics_processing_units#Gen8>;.

CVE-2019-11135

It was discovered that on Intel CPUs supporting transactional
memory (TSX), a transaction that is going to be aborted may
continue to execute speculatively, reading sensitive data from
internal buffers and leaking it through dependent operations.
Intel calls this "TSX Asynchronous Abort" (TAA).

For CPUs affected by the previously published Microarchitectural
Data Sampling (MDS) issues (CVE-2018-12126, CVE-2018-12127,
CVE-2018-12130, CVE-2019-11091), the existing mitigation also
mitigates this issue.

For processors that are vulnerable to TAA but not MDS, this update
disables TSX by default.  This mitigation requires updated CPU
microcode.  An updated intel-microcode package (only available in
Debian non-free) will be provided via a future DLA.  The updated
CPU microcode may also be available as part of a system firmware
("BIOS") update.

Further information on the mitigation can be found at
<https://www.kernel.org/doc/html/latest/admin-guide/hw-vuln/tsx_async_abort.html>
or in the linux-doc-3.16 package.

Intel's explanation of the issue can be found at
<https://software.intel.com/security-software-guidance/insights/deep-dive-intel-transactional-synchronization-extensions-intel-tsx-asynchronous-abort>;.

For Debian 8 "Jessie", these problems have been fixed in version
3.16.76-1. This update also includes other fixes from upstream stable
updates.

We recommend that you upgrade your linux packages.

Further information about Debian LTS security advisories, how to apply
these updates to your system and frequently asked questions can be
found at: https://wiki.debian.org/LTS

–
Ben Hutchings - Debian developer, member of kernel, installer and LTS teams
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