From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id E5F88C3DA7A for ; Thu, 5 Jan 2023 11:13:26 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S231519AbjAELN0 (ORCPT ); Thu, 5 Jan 2023 06:13:26 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:51960 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S231496AbjAELNY (ORCPT ); Thu, 5 Jan 2023 06:13:24 -0500 Received: from out3-smtp.messagingengine.com (out3-smtp.messagingengine.com [66.111.4.27]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 0984FDFB2; Thu, 5 Jan 2023 03:13:21 -0800 (PST) Received: from compute2.internal (compute2.nyi.internal [10.202.2.46]) by mailout.nyi.internal (Postfix) with ESMTP id 7CAB65C0217; Thu, 5 Jan 2023 06:13:20 -0500 (EST) Received: from mailfrontend2 ([10.202.2.163]) by compute2.internal (MEProxy); Thu, 05 Jan 2023 06:13:20 -0500 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=kroah.com; h=cc :cc:content-type:date:date:from:from:in-reply-to:in-reply-to :message-id:mime-version:references:reply-to:sender:subject :subject:to:to; s=fm2; t=1672917200; x=1673003600; bh=MlE9dXjnxE uaB1SpiJoDafHMm0b0Dvnr1NzJJpalc+A=; b=DS6GAtox3oYuPPb0fM0VAZK5E+ qMJhSUZgmOrcvzaTyO9Cvrr5NXgoTqhhm9wVDxDqJAvnOVvnsheqQnLK8M9awhE6 qwC3FZJRwkZqMCIQLPr46CDdYlC15uqCjoOqOJcHKcdg3wQinYeHhDB5OLzmllD/ RQ6bHIz7qDoMEH7wfPtM2NA+JfLEqq+1H0a3ns0Xq2RSz0nUmtDaWa2j+APKoIrz KAYFOaTXukAXOGbdi9TSGlbV/52gvTlVS6w40BxOZCiIQ3YSsM1NwWBYOjOkjciT wA5kUR9nxNob7WNyVy/JB6Bf8mLvJEor+AzX+4mAFtofote2XjHiPR60Bxkg== DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d= messagingengine.com; h=cc:cc:content-type:date:date:feedback-id :feedback-id:from:from:in-reply-to:in-reply-to:message-id :mime-version:references:reply-to:sender:subject:subject:to:to :x-me-proxy:x-me-proxy:x-me-sender:x-me-sender:x-sasl-enc; s= fm2; t=1672917200; x=1673003600; bh=MlE9dXjnxEuaB1SpiJoDafHMm0b0 Dvnr1NzJJpalc+A=; b=k1IqUz3mSg66Q2RSeyGw3slzqtXbeujKO96OFZbHxGdT dx4jvjMl0enM43DWZMBqABabmq4+H1/91HAHDDb/DEgs78z+5om6niRHhE4FAmOQ srakdaZKYJl6NfD6WlI8+EiamDd/acwt67Tpy+xbgUshOIF5CryPV+WeZUGWBfnW 3aQ8q98pe5gkSzbSiV2GmbfMQ3XWsS6uUUCxsqd0JhfFP1x+nOicVVnehyE1MiBs xPCaO1wE3H2cnwtRU2O5XuSSphRL0mALnYlGXhI0S/KeLe+KhSj8DPjmWnDb7Qr6 Uli/HSduaGlf8uU3VYEVnJkCh9aX+O3MkqbdCyVGSw== X-ME-Sender: X-ME-Received: X-ME-Proxy-Cause: gggruggvucftvghtrhhoucdtuddrgedvhedrjeekgddviecutefuodetggdotefrodftvf curfhrohhfihhlvgemucfhrghsthforghilhdpqfgfvfdpuffrtefokffrpgfnqfghnecu uegrihhlohhuthemuceftddtnecusecvtfgvtghiphhivghnthhsucdlqddutddtmdenuc fjughrpeffhffvvefukfhfgggtuggjsehttdertddttddvnecuhfhrohhmpefirhgvghcu mffjuceoghhrvghgsehkrhhorghhrdgtohhmqeenucggtffrrghtthgvrhhnpeegheeuhe fgtdeluddtleekfeegjeetgeeikeehfeduieffvddufeefleevtddtvdenucffohhmrghi nhepkhgvrhhnvghlrdhorhhgnecuvehluhhsthgvrhfuihiivgeptdenucfrrghrrghmpe hmrghilhhfrhhomhepghhrvghgsehkrhhorghhrdgtohhm X-ME-Proxy: Feedback-ID: i787e41f1:Fastmail Received: by mail.messagingengine.com (Postfix) with ESMTPA; Thu, 5 Jan 2023 06:13:19 -0500 (EST) Date: Thu, 5 Jan 2023 12:13:16 +0100 From: Greg KH To: Ard Biesheuvel Cc: Mark Rutland , Lee Jones , stable@vger.kernel.org, linux-efi@vger.kernel.org, linux-arm-kernel@lists.infradead.org, will@kernel.org, catalin.marinas@arm.com, Sami Tolvanen , Kees Cook Subject: Re: [PATCH 1/2] arm64: efi: Execute runtime services from a dedicated stack Message-ID: References: <20221205201210.463781-1-ardb@kernel.org> <20221205201210.463781-2-ardb@kernel.org> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: Precedence: bulk List-ID: X-Mailing-List: linux-efi@vger.kernel.org On Wed, Jan 04, 2023 at 05:32:18PM +0100, Ard Biesheuvel wrote: > On Wed, 4 Jan 2023 at 17:30, Mark Rutland wrote: > > > > On Wed, Jan 04, 2023 at 05:15:34PM +0100, Ard Biesheuvel wrote: > > > On Wed, 4 Jan 2023 at 17:13, Mark Rutland wrote: > > > > > > > > On Wed, Jan 04, 2023 at 02:56:19PM +0100, Ard Biesheuvel wrote: > > > > > On Wed, 4 Jan 2023 at 11:40, Lee Jones wrote: > > > > > > > > > > > > On Mon, 05 Dec 2022, Ard Biesheuvel wrote: > > > > > > > > > > > > > With the introduction of PRMT in the ACPI subsystem, the EFI rts > > > > > > > workqueue is no longer the only caller of efi_call_virt_pointer() in the > > > > > > > kernel. This means the EFI runtime services lock is no longer sufficient > > > > > > > to manage concurrent calls into firmware, but also that firmware calls > > > > > > > may occur that are not marshalled via the workqueue mechanism, but > > > > > > > originate directly from the caller context. > > > > > > > > > > > > > > For added robustness, and to ensure that the runtime services have 8 KiB > > > > > > > of stack space available as per the EFI spec, introduce a spinlock > > > > > > > protected EFI runtime stack of 8 KiB, where the spinlock also ensures > > > > > > > serialization between the EFI rts workqueue (which itself serializes EFI > > > > > > > runtime calls) and other callers of efi_call_virt_pointer(). > > > > > > > > > > > > > > While at it, use the stack pivot to avoid reloading the shadow call > > > > > > > stack pointer from the ordinary stack, as doing so could produce a > > > > > > > gadget to defeat it. > > > > > > > > > > > > > > Signed-off-by: Ard Biesheuvel > > > > > > > --- > > > > > > > arch/arm64/include/asm/efi.h | 3 +++ > > > > > > > arch/arm64/kernel/efi-rt-wrapper.S | 13 +++++++++- > > > > > > > arch/arm64/kernel/efi.c | 25 ++++++++++++++++++++ > > > > > > > 3 files changed, 40 insertions(+), 1 deletion(-) > > > > > > > > > > > > Could we have this in Stable please? > > > > > > > > > > > > Upstream commit: ff7a167961d1b ("arm64: efi: Execute runtime services from a dedicated stack") > > > > > > > > > > > > Ard, do we need Patch 2 as well, or can this be applied on its own? > > > > > > > > > > > > > > > > Thanks for the reminder. > > > > > > > > > > Only patch #1 is needed. It should be applied to v5.10 and later. > > > > > > > > Hold on, why did this go into mainline when I had an outstanding comment w.r.t. > > > > the stack unwinder? > > > > > > > > From your last reply to me there I was expecting a respin with that fixed. > > > > > > > > > > Apologies for the confusion. > > > > > > I have a patch for this queued up, but AIUI, that cannot be merged all > > > the way back to v5.10, so these need to remain separate changes in any > > > case. > > > > > > https://git.kernel.org/pub/scm/linux/kernel/git/next/linux-next.git/commit/?id=c2530a04a73e6b75ed71ed14d09d7b42d6300013 > > > > Ah, ok, thanks for the pointer! > > > > I'm a little uneasy here, still. > > > > By backporting this we're also backporting the new breakage of the stack > > unwinder, and the minimal change for backports would be to add the lock and not > > the new stack (which was added for additinoal robustness, not to fix the bug > > the lock fixes). > > > > I do appreciate that the additional stack is likely more useful than the > > occasional diagnostic output from the kernel, but it does seem like this has > > traded off one bug for another, and I'm just a little annoyed because I pointed > > that out before the first pull request was made. > > > > I do know that this isn't malicious, and I'm not trying to start a fight, but > > now we have to consider whether we want/need to backport a stack unwinder fix > > to account for this, and we hadn't had that discussion before. > > > > In that case, let's drop these backports for the time being, and > collaborate on a solution that works for all of us. > > Greg, could you please drop these again? Thanks. Dropped now from all queues, thanks. greg k-h