linux-kernel - Re: [PATCH] x86/tdx: Fix data leak in mmio

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Message-ID: <zz4zxwnmvtcaadlu743s7wcmc4weblvzyy5cpoy7qberd3ckoj@ovsehcctbewb>
Date: Mon, 26 Aug 2024 22:44:14 +0300
From: "Kirill A. Shutemov" <kirill.shutemov@...ux.intel.com>
To: Dave Hansen <dave.hansen@...el.com>
Cc: Thomas Gleixner <tglx@...utronix.de>, Ingo Molnar <mingo@...hat.com>, 
	Borislav Petkov <bp@...en8.de>, Dave Hansen <dave.hansen@...ux.intel.com>, x86@...nel.org, 
	"H. Peter Anvin" <hpa@...or.com>, linux-kernel@...r.kernel.org, linux-coco@...ts.linux.dev, 
	Sean Christopherson <seanjc@...gle.com>, stable@...r.kernel.org
Subject: Re: [PATCH] x86/tdx: Fix data leak in mmio_read()

On Mon, Aug 26, 2024 at 09:41:49AM -0700, Dave Hansen wrote:
> On 8/26/24 05:53, Kirill A. Shutemov wrote:
> > The mmio_read() function makes a TDVMCALL to retrieve MMIO data for an
> > address from the VMM.
> > 
> > Sean noticed that mmio_read() unintentionally exposes the value of an
> > initialized variable on the stack to the VMM.
> > 
> > Do not send the original value of *val to the VMM.
> 
> The key to this is that 'val' is only used for the _return_ value, right?

Correct.

-- 
  Kiryl Shutsemau / Kirill A. Shutemov