linux-kernel - Re: [PATCH v6 15/22] objtool: Add action to check for absence of absolute relocations

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: <20250811072013.GNaJmZrWDWsZQY_Eig@fat_crate.local>
Date: Mon, 11 Aug 2025 09:20:13 +0200
From: Borislav Petkov <bp@...en8.de>
To: Ard Biesheuvel <ardb+git@...gle.com>,
	Josh Poimboeuf <jpoimboe@...nel.org>,
	Peter Zijlstra <peterz@...radead.org>
Cc: linux-kernel@...r.kernel.org, linux-efi@...r.kernel.org, x86@...nel.org,
	Ard Biesheuvel <ardb@...nel.org>, Ingo Molnar <mingo@...nel.org>,
	Kevin Loughlin <kevinloughlin@...gle.com>,
	Tom Lendacky <thomas.lendacky@....com>,
	Nikunj A Dadhania <nikunj@....com>
Subject: Re: [PATCH v6 15/22] objtool: Add action to check for absence of
 absolute relocations

On Tue, Jul 22, 2025 at 09:27:24AM +0200, Ard Biesheuvel wrote:
> From: Ard Biesheuvel <ardb@...nel.org>
> 
> The x86 startup code must not use absolute references to code or data,
> as it executes before the kernel virtual mapping is up.
> 
> Add an action to objtool to check all allocatable sections (with the
> exception of __patchable_function_entries, which uses absolute
> references for nebulous reasons) and raise an error if any absolute
> references are found.
> 
> Note that debug sections typically contain lots of absolute references
> too, but those are not allocatable so they will be ignored.
> 
> Signed-off-by: Ard Biesheuvel <ardb@...nel.org>
> ---
>  tools/objtool/arch/x86/decode.c         | 12 ++++++
>  tools/objtool/builtin-check.c           |  2 +
>  tools/objtool/check.c                   | 44 ++++++++++++++++++++
>  tools/objtool/include/objtool/arch.h    |  1 +
>  tools/objtool/include/objtool/builtin.h |  1 +
>  5 files changed, 60 insertions(+)

Looks ok to me.

Peter, Josh?

-- 
Regards/Gruss,
    Boris.

https://people.kernel.org/tglx/notes-about-netiquette