Hi Greg,
commit 92d34134193e ("jfs: Fix inconsistency between memory allocation and ea_buf->max_size") fixes CVE-2018-12233. As far as I can see, the commit is not in any stable releases. It applies to all stable releases at least as far back as v4.4.y (and it builds unless I really messed up).
Copying author and committer in case there are any concerns. Otherwise, please apply to stable releases.
Thanks, Guenter