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a="1971265" X-IronPort-AV: E=Sophos;i="6.27,183,1787036400"; d="scan'208";a="1971265" Received: from orviesa005.jf.intel.com ([10.64.159.145]) by fmvoesa111.fm.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 28 Oct 2026 13:51:00 -0700 X-CSE-ConnectionGUID: CfVnjuYjSD+ILdf6xGMCow== X-CSE-MsgGUID: 07F29Qw8Trim9omE97SzGw== X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="6.27,183,1787036400"; d="scan'208";a="4860617" Received: from jjgreens-desk24.amr.corp.intel.com (HELO [10.125.108.218]) ([10.125.108.218]) by smtpauth.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 28 Oct 2026 13:51:00 -0700 Message-ID: <3d982c1c-4c97-4dbc-958a-4e71131c0020@intel.com> Date: Wed, 28 Oct 2026 13:50:59 -0700 X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Post: List-Help: List-Subscribe: List-Unsubscribe: List-Owner: Precedence: list MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH] x86/entry/32: Harden return-to-user To: s1nkhole Cc: x86@kernel.org, Andy Lutomirski , Thomas Gleixner , Ingo Molnar , Borislav Petkov , Dave Hansen , hpa@zytor.com, Peter Zijlstra , Kees Cook , Brian Gerst , Pawan Gupta , linux-hardening@vger.kernel.org, linux-kernel@vger.kernel.org References: <20261028192139.32606-1-dedemorow@gmail.com> From: Dave Hansen Content-Language: en-US Autocrypt: addr=dave.hansen@intel.com; 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charset=UTF-8 Content-Transfer-Encoding: 7bit On 10/28/26 12:21, s1nkhole wrote: > If you have a moment: this is my first work on arch/x86, and I would like > to contribute something that is actually useful. Is there a small task > in x86/entry or in kernel hardening that you would suggest as a better > starting point, or a place where help with testing or review would be > welcome? I can build and run kernels under QEMU. It's not small, but kernel shadow stacks are an _incredibly_ powerful hardening tool. You can buy a system off the shelf that sanely supports them (including FRED), but the kernel doesn't support them yet. My current work in progress is here: > https://git.kernel.org/pub/scm/linux/kernel/git/daveh/devel.git/log/?h=kss-2026-10-23 Another set of eyes on that would be nice. Although I do think I'm going to abandon tacking the shadow stack on to the thread_union for now. So I don't suggest looking at it too deeply until I get another version out the door. One thing you could do today is go into the list in here: > https://git.kernel.org/pub/scm/linux/kernel/git/daveh/devel.git/commit/?h=kss-2026-10-21&id=4dab5fe58904ee07b3622f25bbe3c1b7ff820bf5 and pick a feature or two and figure out if they need fixing for shadow stacks or not, and if so what a fix might look like. Or another set of eyes on this: > https://git.kernel.org/pub/scm/linux/kernel/git/daveh/devel.git/log/?h=taskfun-2026-10-26 It's ready to post but I'm just waiting for the merge window to close.