Linux XFS has a decade-old race condition allowing full root access

Linux systems using the XFS filesystem suffer from a race condition that could enable an unprivileged local user to gain full root access. The flaw affects systems with Linux kernel 4.11 or later that have enabled the XFS feature reflink, which permits the creation of copies of a file without actually copying its data. According to Qualys Threat Research Unit (TRU), there was a way around the file write protections reflink depends on.