ksmbd: fix slab-out-of-bounds in smb_strndup_from_utf16()
In the Linux kernel, the following vulnerability has been resolved:

ksmbd: fix slab-out-of-bounds in smb_strndup_from_utf16()

If ->NameOffset of smb2_create_req is smaller than Buffer offset of
smb2_create_req, slab-out-of-bounds read can happen from smb2_open.
This patch set the minimum value of the name offset to the buffer offset
to validate name length of smb2_create_req().