Oracle Linux: CVE-2016-2143: ELSA-2016-1539: kernel security and bug fix update (IMPORTANT) (Multiple Advisories)

The fork implementation in the Linux kernel before 4.5 on s390 platforms mishandles the case of four page-table levels, which allows local users to cause a denial of service (system crash) or possibly have unspecified other impact via a crafted application, related to arch/s390/include/asm/mmu_context.h and arch/s390/include/asm/pgalloc.h.
It was reported that on s390x, the fork of a process with four page table levels will cause memory corruption with a variety of symptoms. All processes are created with three level page table and a limit of 4TB for the address space. If the parent process has four page table levels with a limit of 8PB, the function that duplicates the address space will try to copy memory areas outside of the address space limit for the child process.