linux-kernel - Re: [PATCH v6 2/3] x86/entry_32: Clear CPU buffers after register restore in NMI return

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Message-ID: <d7c9d883-72d5-4258-8f36-be4268acf581@intel.com>
Date: Thu, 12 Sep 2024 10:39:13 -0700
From: Dave Hansen <dave.hansen@...el.com>
To: Pawan Gupta <pawan.kumar.gupta@...ux.intel.com>,
 Borislav Petkov <bp@...en8.de>, Dave Hansen <dave.hansen@...ux.intel.com>
Cc: linux-kernel@...r.kernel.org, x86@...nel.org,
 Robert Gill <rtgill82@...il.com>, Jari Ruusu <jariruusu@...tonmail.com>,
 Brian Gerst <brgerst@...il.com>,
 "Linux regression tracking (Thorsten Leemhuis)" <regressions@...mhuis.info>,
 antonio.gomez.iglesias@...ux.intel.com, daniel.sneddon@...ux.intel.com
Subject: Re: [PATCH v6 2/3] x86/entry_32: Clear CPU buffers after register
 restore in NMI return

On 9/5/24 09:00, Pawan Gupta wrote:
> CPU buffers are currently cleared after call to exc_nmi, but before
> register state is restored. This may be okay for MDS mitigation but not for
> RDFS. Because RDFS mitigation requires CPU buffers to be cleared when
> registers don't have any sensitive data.
> 
> Move CLEAR_CPU_BUFFERS after RESTORE_ALL_NMI.

This needs some grammar tweaking, but we can do that when it get applied.

Acked-by: Dave Hansen <dave.hansen@...ux.intel.com>