This kernel update is based on the upstream 4.14.20 and and adds KPTI mitigation for Meltdown (CVE-2017-5754) on 32bit x86. Arm platorm has now also addedmitigations for Meltdown (CVE-2017-5754) and Spectre, variant 2 (CVE-2017-5715).
For other fixes in this update, read the referenced changelogs.