Re: [PATCH] x86/lam: Disable ADDRESS_MASKING in most cases

[kirill . shutemov]

On Thu, Jan 18, 2024 at 06:35:47PM -0800, Pawan Gupta wrote:
> Intel feature Linear Address Masking (LAM) has a weakness related to
> transient execution as described in the SLAM paper[1]. Unless Linear
> Address Space Separation (LASS) is enabled this weakness may be
> exploitable.
> 
> Until kernel adds support for LASS[2], only allow LAM for COMPILE_TEST,
> or when speculation mitigations have been disabled at compile time,
> otherwise keep LAM disabled.
> 

It worth adding that there's no HW on market that supports LAM, so nobody
affected by the issue.

> [1] SLAM: https://download.vusec.net/papers/slam_sp24.pdf
> [2] LASS: https://lore.kernel.org/lkml/20230609183632.48706-1-alexander.shishkin@xxxxxxxxxxxxxxx/
> 
> Cc: stable@xxxxxxxxxxxxxxx # v6.4+
> Signed-off-by: Pawan Gupta <pawan.kumar.gupta@xxxxxxxxxxxxxxx>

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

-- 
  Kiryl Shutsemau / Kirill A. Shutemov