Re: [PATCH RFC] x86/sgx: Check that the address is within ELRANGE

[Sean Christopherson <sean.j.christopherson@intel.com>]

On Thu, Jun 13, 2019 at 07:42:40PM +0300, Jarkko Sakkinen wrote:
> In sgx_encl_page_alloc() check that the given address within the
> ELRANGE. Return -EINVAL if not.
> 
> Reported-by: Shay Katz-zamir <shay.katz-zamir@intel.com>
> Cc: Sean Christopherson <sean.j.christopherson@intel.com>
> Signed-off-by: Jarkko Sakkinen <jarkko.sakkinen@linux.intel.com>
> ---
>  arch/x86/kernel/cpu/sgx/driver/ioctl.c | 7 +++++++
>  1 file changed, 7 insertions(+)
> 
> diff --git a/arch/x86/kernel/cpu/sgx/driver/ioctl.c b/arch/x86/kernel/cpu/sgx/driver/ioctl.c
> index d17c60dca114..9d3fc770b4d9 100644
> --- a/arch/x86/kernel/cpu/sgx/driver/ioctl.c
> +++ b/arch/x86/kernel/cpu/sgx/driver/ioctl.c
> @@ -240,19 +240,26 @@ static struct sgx_encl_page *sgx_encl_page_alloc(struct sgx_encl *encl,
>  	struct sgx_encl_page *encl_page;
>  	int ret;
>  
> +	if (addr < encl->base || addr > (encl->base + encl->size))

The upper bounds check should be "addr >= (encl->base + encl->size)" or
"addr > (encl->base + encl->size - 1)"

> +		return ERR_PTR(-EINVAL);
> +
>  	if (radix_tree_lookup(&encl->page_tree, PFN_DOWN(addr)))
>  		return ERR_PTR(-EEXIST);
> +
>  	encl_page = kzalloc(sizeof(*encl_page), GFP_KERNEL);
>  	if (!encl_page)
>  		return ERR_PTR(-ENOMEM);
> +
>  	encl_page->desc = addr;
>  	encl_page->encl = encl;
> +
>  	ret = radix_tree_insert(&encl->page_tree, PFN_DOWN(encl_page->desc),
>  				encl_page);
>  	if (ret) {
>  		kfree(encl_page);
>  		return ERR_PTR(ret);
>  	}
> +
>  	return encl_page;
>  }
>  
> -- 
> 2.20.1
>