Race condition in mm/gup.c in the Linux kernel 2.x through 4.x before 4.8.3
allows local users to gain privileges by leveraging incorrect handling of a
copy-on-write (COW) feature to write to a read-only memory mapping, as
exploited in the wild in October 2016, aka "Dirty COW."

It was discovered that a race condition existed in the memory manager of
the Linux kernel when handling copy-on-write breakage of private read-only
memory mappings. A local attacker could use this to gain administrative
privileges.