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

[Pawan Gupta]

On Fri, Jan 19, 2024 at 07:58:28AM +0300, kirill.shutemov@xxxxxxxxxxxxxxx wrote:
> 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.

Right.

> > [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>

Thanks.