From: Sohil Mehta <sohil.mehta@intel.com>
To: "Edgecombe, Rick P" <rick.p.edgecombe@intel.com>,
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Subject: Re: [PATCH v10 04/15] x86/cpu: Set LASS CR4 bit as pinning sensitive
Date: Tue, 7 Oct 2025 16:11:51 -0700 [thread overview]
Message-ID: <7635c45d-97b3-4773-95db-e61ad872ce22@intel.com> (raw)
In-Reply-To: <e873d2b06a18b69e246f8011c556259d21c7e022.camel@intel.com>
On 10/7/2025 11:24 AM, Edgecombe, Rick P wrote:
>> Security features such as LASS are not expected to be disabled once
>> initialized. Add LASS to the CR4 pinned mask.
>>
>
> I was debating whether we really need this, given the LASS and CR pinning threat
> models. CR pinning seems to be about after an attacker has already hijacked a
> control flow and is looking to escalate it into more control.
Can you please explain more? How is LASS different from SMAP and SMEP
for which the CR pinning code was initially added?
> We could maybe get
> away with dropping this and the following patch. But it would still be good to
> get a warning if it gets turned off inadvertently I think. It might be worth
> adding justification like that to the log.
My understanding from the previous discussions was that CR pinning
deferral might be beneficial independent of LASS.
https://lore.kernel.org/lkml/c59aa7ac-62a6-45ec-b626-de518b25f7d9@intel.com/
The pinning enforcement provides the warning and reprograms the bit.
Maybe, I've misunderstood your comment.
next prev parent reply other threads:[~2025-10-07 23:12 UTC|newest]
Thread overview: 74+ messages / expand[flat|nested] mbox.gz Atom feed top
2025-10-07 6:51 [PATCH v10 00/15] x86: Enable Linear Address Space Separation support Sohil Mehta
2025-10-07 6:51 ` [PATCH v10 01/15] x86/cpu: Enumerate the LASS feature bits Sohil Mehta
2025-10-07 18:19 ` Edgecombe, Rick P
2025-10-07 18:28 ` Dave Hansen
2025-10-07 20:20 ` Sohil Mehta
2025-10-07 20:38 ` Edgecombe, Rick P
2025-10-07 20:53 ` Sohil Mehta
2025-10-16 3:10 ` H. Peter Anvin
2025-10-07 20:49 ` Sohil Mehta
2025-10-07 23:16 ` Xin Li
2025-10-08 16:00 ` Edgecombe, Rick P
2025-10-16 15:35 ` Borislav Petkov
2025-10-21 18:03 ` Sohil Mehta
2025-10-07 6:51 ` [PATCH v10 02/15] x86/asm: Introduce inline memcpy and memset Sohil Mehta
2025-10-21 12:47 ` Borislav Petkov
2025-10-21 13:48 ` David Laight
2025-10-21 18:06 ` Sohil Mehta
2025-10-07 6:51 ` [PATCH v10 03/15] x86/alternatives: Disable LASS when patching kernel alternatives Sohil Mehta
2025-10-07 16:55 ` Edgecombe, Rick P
2025-10-07 22:28 ` Sohil Mehta
2025-10-08 16:22 ` Edgecombe, Rick P
2025-10-10 17:10 ` Sohil Mehta
2025-10-21 20:03 ` Borislav Petkov
2025-10-21 20:55 ` Sohil Mehta
2025-10-22 9:56 ` Borislav Petkov
2025-10-22 19:49 ` Sohil Mehta
2025-10-22 20:03 ` Luck, Tony
2025-10-22 8:25 ` Peter Zijlstra
2025-10-22 9:40 ` Borislav Petkov
2025-10-22 10:22 ` Peter Zijlstra
2025-10-22 10:52 ` Borislav Petkov
2025-10-07 6:51 ` [PATCH v10 04/15] x86/cpu: Set LASS CR4 bit as pinning sensitive Sohil Mehta
2025-10-07 18:24 ` Edgecombe, Rick P
2025-10-07 23:11 ` Sohil Mehta [this message]
2025-10-08 16:52 ` Edgecombe, Rick P
2025-10-10 19:03 ` Sohil Mehta
2025-10-07 6:51 ` [PATCH v10 05/15] x86/cpu: Defer CR pinning enforcement until late_initcall() Sohil Mehta
2025-10-07 17:23 ` Edgecombe, Rick P
2025-10-07 23:05 ` Sohil Mehta
2025-10-08 17:36 ` Edgecombe, Rick P
2025-10-10 20:45 ` Sohil Mehta
2025-10-15 21:17 ` Sohil Mehta
2025-10-17 19:28 ` Sohil Mehta
2025-10-07 6:51 ` [PATCH v10 06/15] x86/efi: Disable LASS while mapping the EFI runtime services Sohil Mehta
2025-10-07 6:51 ` [PATCH v10 07/15] x86/kexec: Disable LASS during relocate kernel Sohil Mehta
2025-10-07 17:43 ` Edgecombe, Rick P
2025-10-07 22:33 ` Sohil Mehta
2025-10-07 6:51 ` [PATCH v10 08/15] x86/vsyscall: Reorganize the page fault emulation code Sohil Mehta
2025-10-07 18:37 ` Edgecombe, Rick P
2025-10-07 18:48 ` Dave Hansen
2025-10-07 19:53 ` Edgecombe, Rick P
2025-10-07 22:52 ` Sohil Mehta
2025-10-08 17:42 ` Edgecombe, Rick P
2025-10-30 16:58 ` Andy Lutomirski
2025-10-30 17:22 ` H. Peter Anvin
2025-10-30 17:35 ` Andy Lutomirski
2025-10-30 19:28 ` Sohil Mehta
2025-10-30 21:37 ` David Laight
2025-10-07 6:51 ` [PATCH v10 09/15] x86/traps: Consolidate user fixups in exc_general_protection() Sohil Mehta
2025-10-07 17:46 ` Edgecombe, Rick P
2025-10-07 22:41 ` Sohil Mehta
2025-10-08 17:43 ` Edgecombe, Rick P
2025-10-07 6:51 ` [PATCH v10 10/15] x86/vsyscall: Add vsyscall emulation for #GP Sohil Mehta
2025-10-07 6:51 ` [PATCH v10 11/15] x86/vsyscall: Disable LASS if vsyscall mode is set to EMULATE Sohil Mehta
2025-10-07 18:43 ` Edgecombe, Rick P
2025-10-07 6:51 ` [PATCH v10 12/15] x86/traps: Communicate a LASS violation in #GP message Sohil Mehta
2025-10-07 18:07 ` Edgecombe, Rick P
2025-10-07 6:51 ` [PATCH v10 13/15] x86/traps: Generalize #GP address decode and hint code Sohil Mehta
2025-10-07 18:43 ` Edgecombe, Rick P
2025-10-07 6:51 ` [PATCH v10 14/15] x86/traps: Provide additional hints for a kernel stack segment fault Sohil Mehta
2025-10-07 6:51 ` [PATCH v10 15/15] x86/cpu: Enable LASS by default during CPU initialization Sohil Mehta
2025-10-07 18:42 ` Edgecombe, Rick P
2025-10-07 16:23 ` [PATCH v10 00/15] x86: Enable Linear Address Space Separation support Edgecombe, Rick P
2025-10-17 19:52 ` Sohil Mehta
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