Re: [PATCH v17 18/23] platform/x86: Intel SGX driver

[Dave Hansen]

> +struct sgx_encl *sgx_encl_alloc(struct sgx_secs *secs)
> +{
...
> +	kref_init(&encl->refcount);
> +	INIT_LIST_HEAD(&encl->add_page_reqs);
> +	INIT_RADIX_TREE(&encl->page_tree, GFP_KERNEL);
> +	mutex_init(&encl->lock);
> +	INIT_WORK(&encl->add_page_work, sgx_add_page_worker);
> +
> +	encl->mm = current->mm;  <---------------------------------> +	encl->base = secs->base;
> +	encl->size = secs->size;
> +	encl->ssaframesize = secs->ssa_frame_size;
> +	encl->backing = backing;
> +
> +	return encl;
> +}

How is this OK without taking a reference on the mm?

I have a feeling a bunch of your bugs with the mmu notifiers and so
forth are because the refcounting is wrong here.

Sean's SGX_ENCL_MM_RELEASED would, I think be unnecessary if you just
take a refcount here and release it when the enclave is destroyed.