Re: [PULL] vhost: cleanups and fixes

[Linus Torvalds]

On Thu, Nov 1, 2018 at 4:00 PM Kees Cook <keescook@xxxxxxxxxxxx> wrote:
>
> +       memset(&rsp, 0, sizeof(rsp));
> +       rsp.response = VIRTIO_SCSI_S_FUNCTION_REJECTED;
> +       resp = vq->iov[out].iov_base;
> +       ret = __copy_to_user(resp, &rsp, sizeof(rsp));
>
> Is it actually safe to trust that iov_base has passed an earlier
> access_ok() check here? Why not just use copy_to_user() instead?

Good point.

We really should have removed those double-underscore things ages ago.

Also, apart from the address, what about the size? Wouldn't it be
better to use copy_to_iter() rather than implement it badly by hand?

               Linus