The aio_mount function in fs/aio.c in the Linux kernel before 4.7.7 does not properly restrict execute access, which makes it easier for local users to bypass intended SELinux W^X policy restrictions, and consequently gain privileges, via an io_setup system call.
https://github.com/torvalds/linux/commit/22f6b4d34fcf039c63a94e7670e0da24f8575a5a