From: Alexander Shishkin <alexander.shishkin@linux.intel.com>
To: Matthew Wilcox <willy@infradead.org>
Cc: Andy Lutomirski <luto@kernel.org>,
Thomas Gleixner <tglx@linutronix.de>,
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linux-doc@vger.kernel.org, linux-kernel@vger.kernel.org,
linux-efi@vger.kernel.org, alexander.shishkin@linux.intel.com
Subject: Re: [PATCH v5 00/16] Enable Linear Address Space Separation support
Date: Wed, 30 Oct 2024 09:16:05 +0200 [thread overview]
Message-ID: <87plnit616.fsf@ubik.fi.intel.com> (raw)
In-Reply-To: <ZyEX4cp-iiwiF_yX@casper.infradead.org>
Matthew Wilcox <willy@infradead.org> writes:
> On Mon, Oct 28, 2024 at 06:07:48PM +0200, Alexander Shishkin wrote:
> I lack the wit to read & understand these patches to answer this
> question, so I'll just ask it:
I was hoping they are readable and straightforward. Please, do point out
things that are not so, or not explained well enough, I'll fix them.
> What happens when the kernel does a NULL pointer dereference (due to a
> bug)? It's not an attempt to access userspace, but it should result in
> a good bug report. Normally this would be outside a STAC/CLAC region,
> but I suppose technically it could be within one.
Outside of STAC/CLAC there will be a message, see 13/16 or [0]. It
doesn't have helpful things like "if (address < PAGE_SIZE) printk("NULL
ptr deref\n);", but since it prints the address, I assumed it was
sufficient. Does this sound reasonable? Or is it preferrable to make it
look exactly like the !LASS NULL dereference?
Inside STAC/CLAC it should trigger a regular page fault and all the
error messages that result from it.
[0] https://lore.kernel.org/all/20241028160917.1380714-14-alexander.shishkin@linux.intel.com/
Thanks,
--
Alex
prev parent reply other threads:[~2024-10-30 7:16 UTC|newest]
Thread overview: 42+ messages / expand[flat|nested] mbox.gz Atom feed top
2024-10-28 16:07 [PATCH v5 00/16] Enable Linear Address Space Separation support Alexander Shishkin
2024-10-28 16:07 ` [PATCH v5 01/16] x86/cpu: Enumerate the LASS feature bits Alexander Shishkin
2024-10-29 14:55 ` Kirill A. Shutemov
2024-10-29 21:46 ` Sohil Mehta
2024-10-28 16:07 ` [PATCH v5 02/16] x86/asm: Introduce inline memcpy and memset Alexander Shishkin
2024-10-28 16:07 ` [PATCH v5 03/16] x86/alternatives: Disable LASS when patching kernel alternatives Alexander Shishkin
2024-10-28 17:49 ` Dave Hansen
2024-10-29 11:36 ` Peter Zijlstra
2024-10-29 18:48 ` Peter Zijlstra
2024-10-30 7:40 ` Alexander Shishkin
2024-10-28 16:07 ` [PATCH v5 04/16] init/main.c: Move EFI runtime service initialization to x86/cpu Alexander Shishkin
2024-10-29 22:35 ` Sohil Mehta
2024-10-30 7:36 ` Ard Biesheuvel
2024-10-28 16:07 ` [PATCH v5 05/16] x86/cpu: Defer CR pinning setup until after EFI initialization Alexander Shishkin
2024-10-29 22:10 ` Sohil Mehta
2024-10-29 22:26 ` Luck, Tony
2024-10-29 22:52 ` Dave Hansen
2024-10-29 22:59 ` Luck, Tony
2024-10-29 23:02 ` H. Peter Anvin
2024-10-29 23:03 ` Dave Hansen
2024-10-29 23:05 ` H. Peter Anvin
2024-10-29 23:18 ` Luck, Tony
2024-10-29 23:41 ` H. Peter Anvin
2024-10-30 11:43 ` Kirill A. Shutemov
2024-10-28 16:07 ` [PATCH v5 06/16] efi: Disable LASS around set_virtual_address_map call Alexander Shishkin
2024-10-29 15:00 ` Kirill A. Shutemov
2024-10-28 16:07 ` [PATCH v5 07/16] x86/vsyscall: Reorganize the #PF emulation code Alexander Shishkin
2024-10-28 16:07 ` [PATCH v5 08/16] x86/traps: Consolidate user fixups in exc_general_protection() Alexander Shishkin
2024-10-28 16:07 ` [PATCH v5 09/16] x86/vsyscall: Add vsyscall emulation for #GP Alexander Shishkin
2024-10-28 16:07 ` [PATCH v5 10/16] x86/vsyscall: Disable LASS if vsyscall mode is set to EMULATE Alexander Shishkin
2024-10-28 16:07 ` [PATCH v5 11/16] x86/vsyscall: Document the fact that vsyscall=emulate disables LASS Alexander Shishkin
2024-10-29 23:41 ` Sohil Mehta
2024-10-28 16:08 ` [PATCH v5 12/16] x86/cpu: Set LASS CR4 bit as pinning sensitive Alexander Shishkin
2024-10-28 16:08 ` [PATCH v5 13/16] x86/traps: Communicate a LASS violation in #GP message Alexander Shishkin
2024-10-28 16:08 ` [PATCH v5 14/16] x86/cpu: Make LAM depend on LASS Alexander Shishkin
2024-10-31 0:06 ` Sohil Mehta
2024-10-28 16:08 ` [PATCH v5 15/16] x86/cpu: Enable LASS during CPU initialization Alexander Shishkin
2024-10-28 16:08 ` [PATCH v5 16/16] Revert "x86/lam: Disable ADDRESS_MASKING in most cases" Alexander Shishkin
2024-10-28 20:41 ` Kirill A. Shutemov
2024-10-28 22:00 ` Alexander Shishkin
2024-10-29 17:14 ` [PATCH v5 00/16] Enable Linear Address Space Separation support Matthew Wilcox
2024-10-30 7:16 ` Alexander Shishkin [this message]
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