Describe CVE-2015-4178.
What is CVE-2015-4178?
The fs_pin implementation in the Linux kernel before 4.0.5 does not ensure the internal consistency of a certain list data structure, which allows local users to cause a denial of service (system crash) by leveraging user-namespace root access for an MNT_DETACH umount2 system call, related to fs/fs_pin.c and include/linux/fs_pin.h..