Oracle Linux: CVE-2018-18397: ELSA-2019-4528: Unbreakable Enterprise kernel security update (IMPORTANT) (Multiple Advisories)

The userfaultfd implementation in the Linux kernel before 4.19.7 mishandles access control for certain UFFDIO_ ioctl calls, as demonstrated by allowing local users to write data into holes in a tmpfs file (if the user has read-only access to that file, and that file contains holes), related to fs/userfaultfd.c and mm/userfaultfd.c.
A flaw was found in the Linux kernel with files on tmpfs and hugetlbfs. An attacker is able to bypass file permissions on filesystems mounted with tmpfs/hugetlbs to modify a file and possibly disrupt normal system behavior. At this time there is an understanding there is no crash or privilege escalation but the impact of modifications on these filesystems of files in production systems may have adverse affects.