The mm_init function in kernel/fork.c in the Linux kernel before 4.12.10 does not clear the ->exe_file member of a new process's mm_struct, allowing a local attacker to achieve a use-after-free or possibly have unspecified other impact by running a specially crafted program.
https://www.kernel.org/pub/linux/kernel/v4.x/ChangeLog-4.12.10
https://github.com/torvalds/linux/commit/2b7e8665b4ff51c034c55df3cff76518d1a9ee3a