Re: [PATCH v3 5/5] x86/sgx: Remove redundant if conditions in sgx_encl_create

Greg KH
2021-01-24T08:21:47Z

On Sun, Jan 24, 2021 at 02:29:07PM +0800, Tianjia Zhang wrote:
> In this scenario, there is no case where va_page is NULL, and
> the error has been checked. The if condition statement here is
> redundant, so remove the condition detection.
>
> Signed-off-by: Tianjia Zhang <tianjia.zhang@linux.alibaba.com>
> ---
> arch/x86/kernel/cpu/sgx/ioctl.c | 8 +++++---
> 1 file changed, 5 insertions(+), 3 deletions(-)
>
> diff --git a/arch/x86/kernel/cpu/sgx/ioctl.c b/arch/x86/kernel/cpu/sgx/ioctl.c
> index 1c6ecf9fbeff..b0b829f1b761 100644
> --- a/arch/x86/kernel/cpu/sgx/ioctl.c
> +++ b/arch/x86/kernel/cpu/sgx/ioctl.c
> @@ -66,9 +66,11 @@ static int sgx_encl_create(struct sgx_encl *encl, struct sgx_secs *secs)
> va_page = sgx_encl_grow(encl);
> if (IS_ERR(va_page))
> return PTR_ERR(va_page);
> - else if (va_page)
> - list_add(&va_page->list, &encl->va_pages);
> - /* else the tail page of the VA page list had free slots. */
> +
> + if (WARN_ONCE(!va_page, "non-empty VA page list before ECREATE"))
> + return -EIO;

So you just crashed machines that have panic-on-warn enabled. Don't do
that for no reason, just handle the error and move on.

thanks,

greg k-h