BugLink: https://bugs.launchpad.net/bugs/1884564

commit 84e99e58 upstream.

Add barrier to soob. Return -EOVERFLOW if the buffer
is exceeded.
Suggested-by: Hillf Danton <hdanton@sina.com>
Reported-by: syzbot+bfdd4a2f07be52351350@syzkaller.appspotmail.com
Signed-off-by: Casey Schaufler <casey@schaufler-ca.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: Kamal Mostafa <kamal@canonical.com>
Signed-off-by: Khalid Elmously <khalid.elmously@canonical.com>