In FreeBSD 12.0-STABLE before r347474, 12.0-RELEASE before 12.0-RELEASE-p7, 11.2-STABLE before r347475, and 11.2-RELEASE before 11.2-RELEASE-p11, a bug in the FFS implementation causes up to three bytes of kernel stack memory to be written to disk as uninitialized directory entry padding.
https://security.FreeBSD.org/advisories/FreeBSD-SA-19:10.ufs.asc
http://packetstormsecurity.com/files/153523/FreeBSD-Security-Advisory-FreeBSD-SA-19-10.ufs.html