Re: [PATCH v6 1/6] x86/tdx: Fix "in-kernel MMIO" check

[Kirill A. Shutemov]

On Fri, Sep 06, 2024 at 01:49:59PM +0200, Alexey Gladkov wrote:
> From: "Alexey Gladkov (Intel)" <legion@xxxxxxxxxx>
> 
> TDX only supports kernel-initiated MMIO operations. The handle_mmio()
> function checks if the #VE exception occurred in the kernel and rejects
> the operation if it did not.
> 
> However, userspace can deceive the kernel into performing MMIO on its
> behalf. For example, if userspace can point a syscall to an MMIO address,
> syscall does get_user() or put_user() on it, triggering MMIO #VE. The
> kernel will treat the #VE as in-kernel MMIO.
> 
> Ensure that the target MMIO address is within the kernel before decoding
> instruction.
> 
> Cc: stable@xxxxxxxxxxxxxxx
> Signed-off-by: Alexey Gladkov (Intel) <legion@xxxxxxxxxx>

Reviewed-by: Kirill A. Shutemov <kirill.shutemov@xxxxxxxxxxxxxxx>

-- 
  Kiryl Shutsemau / Kirill A. Shutemov