The do_shmat function in ipc/shm.c in the Linux kernel through 4.9.12 does not restrict the address calculated by a certain rounding operation, which allows local users to map page zero, and consequently bypass a protection mechanism that exists for the mmap system call, by making crafted shmget and shmat system calls in a privileged context. http://web.nvd.nist.gov/view/vuln/detail?vulnId=CVE-2017-5669
