A flaw was found in the Linux kernel that fs/ocfs2/aops.c omits use of a semaphore and consequently has a race condition for access to the extent tree during read operations in DIRECT mode, which allows local users to cause a denial of service by modifying a certain e_cpos field.
An upstream patch:
Created kernel tracking bugs for this issue:
Affects: fedora-all [bug 1557557]
This was fixed for Fedora with the 4.15 rebases.