linux-kernel - Re: [RESEND PATCH 3/3] x86/sgx: Add xa_store_range() return value check in sgx_setup_epc

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Message-ID: <0b22047833ec63106b7b2c97ca0dcda0bd16470b.camel@intel.com>
Date:   Tue, 1 Nov 2022 02:41:39 +0000
From:   "Huang, Kai" <kai.huang@...el.com>
To:     "jarkko@...nel.org" <jarkko@...nel.org>,
        "dave.hansen@...ux.intel.com" <dave.hansen@...ux.intel.com>
CC:     "linux-sgx@...r.kernel.org" <linux-sgx@...r.kernel.org>,
        "Luck, Tony" <tony.luck@...el.com>,
        "Chatre, Reinette" <reinette.chatre@...el.com>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>
Subject: Re: [RESEND PATCH 3/3] x86/sgx: Add xa_store_range() return value
 check in sgx_setup_epc_section()

On Tue, 2022-10-04 at 22:42 +0000, Huang, Kai wrote:
> On Wed, 2022-10-05 at 01:21 +0300, Jarkko Sakkinen wrote:
> > On Tue, Oct 04, 2022 at 11:04:29AM +1300, Kai Huang wrote:
> > > In sgx_setup_epc_section(), xa_store_range() is called to store EPC
> > > pages' owner section to an Xarray using physical addresses of those EPC
> > > pages as index.  Currently, the return value of xa_store_range() is not
> > > checked, but actually it can fail (i.e. due to -ENOMEM).
> > > 
> > > Not checking the return value of xa_store_range() would result in the
> > > EPC section being used by SGX driver (and KVM SGX guests), but part or
> > > all of its EPC pages not being handled by the memory failure handling of
> > > EPC page.  Such inconsistency should be avoided, even at the cost that
> > > this section won't be used by the kernel.
> > > 
> > > Add the missing check of the return value of xa_store_range(), and when
> > > it fails, clean up and fail to initialize the EPC section.
> > > 
> > > Fixes: 40e0e7843e23 ("x86/sgx: Add infrastructure to identify SGX EPC pages")
> > > Signed-off-by: Kai Huang <kai.huang@...el.com>
> > 
> > Reviewed-by: Jarkko Sakkinen <jarkko@...nel.org>
> > 
> > This needs:
> > 
> > Cc: stable@...r.kernel.org # v5.17+
> > 
> > Dave, can you pick this independently of rest of the patch set
> > (unless ofc you have change suggestions)?
> > 
> > BR, Jarkko
> 
> Thanks Jarkko.  I will add the "Cc stable" part if I need to send out a new
> version.
>  
> -- 
> Thanks,
> -Kai
> 

Hi Dave,

Is this patch worth to do?  For now this should be more like a theoretical issue
that I just saw when scanning the code.  If it is worth to do I'll send out a
new one with Jarkko's reviewed-by and CC stable tag.

-- 
Thanks,
-Kai