On Sun, Jan 24, 2021, Greg KH wrote: > 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@xxxxxxxxxxxxxxxxx> > > --- > > 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. The WARN will only fire if someone introduces a kernel bug. It's one part documentation, two parts helping detect future breakage. Even if the VA page management is significantly reworked, I'm having a hard time envisioning a scenario where adding VA pages before ECREATE would be anything but a kernel bug.
