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. http://web.nvd.nist.gov/view/vuln/detail?vulnId=CVE-2016-2143
