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 lists.xenproject.org (lists.xenproject.org [192.237.175.120]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.lore.kernel.org (Postfix) with ESMTPS id 7D465D2C55E for ; Tue, 22 Oct 2024 14:21:30 +0000 (UTC) Received: from list by lists.xenproject.org with outflank-mailman.824225.1238318 (Exim 4.92) (envelope-from ) id 1t3Fkn-0003MI-Pk; Tue, 22 Oct 2024 14:20:57 +0000 X-Outflank-Mailman: Message body and most headers restored to incoming version Received: by outflank-mailman (output) from mailman id 824225.1238318; Tue, 22 Oct 2024 14:20:57 +0000 Received: from localhost ([127.0.0.1] helo=lists.xenproject.org) by lists.xenproject.org with esmtp (Exim 4.92) (envelope-from ) id 1t3Fkn-0003MB-NC; Tue, 22 Oct 2024 14:20:57 +0000 Received: by outflank-mailman (input) for mailman id 824225; Tue, 22 Oct 2024 14:20:55 +0000 Received: from se1-gles-sth1-in.inumbo.com ([159.253.27.254] helo=se1-gles-sth1.inumbo.com) by lists.xenproject.org with esmtp (Exim 4.92) (envelope-from ) id 1t3Fkl-0003Ly-Th for xen-devel@lists.xenproject.org; Tue, 22 Oct 2024 14:20:55 +0000 Received: from mail-lj1-x22e.google.com (mail-lj1-x22e.google.com [2a00:1450:4864:20::22e]) by se1-gles-sth1.inumbo.com (Halon) with ESMTPS id d8f86901-9080-11ef-a0be-8be0dac302b0; Tue, 22 Oct 2024 16:20:54 +0200 (CEST) Received: by mail-lj1-x22e.google.com with SMTP id 38308e7fff4ca-2fb561f273eso56793961fa.2 for ; Tue, 22 Oct 2024 07:20:54 -0700 (PDT) Received: from [10.125.226.166] ([185.25.67.249]) by smtp.gmail.com with ESMTPSA id 4fb4d7f45d1cf-5cb66c726besm3203491a12.93.2024.10.22.07.20.52 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Tue, 22 Oct 2024 07:20:53 -0700 (PDT) X-BeenThere: xen-devel@lists.xenproject.org List-Id: Xen developer discussion List-Unsubscribe: , List-Post: List-Help: List-Subscribe: , Errors-To: xen-devel-bounces@lists.xenproject.org Precedence: list Sender: "Xen-devel" X-Inumbo-ID: d8f86901-9080-11ef-a0be-8be0dac302b0 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=citrix.com; s=google; t=1729606854; x=1730211654; darn=lists.xenproject.org; h=content-transfer-encoding:in-reply-to:autocrypt:from :content-language:references:cc:to:subject:user-agent:mime-version :date:message-id:from:to:cc:subject:date:message-id:reply-to; bh=3f3pXqNyI+bwOtKt5dUl7KO7hRUU1R9j1/G49d53U6A=; b=vvKdhj//oqzVgvxLSe2sfriMMQ6G3WIXBvgQVpijpHyeZGNN18TN1iDiER1fwpQR+Q 2zNbgEPy0HWg3/83hQ5+aShsFd4q5fcGD40RiIVGxLDTgXFhfnPoTWzrGu61P4f+qPFc 1b6kx5A4Y3Y3lSzPmXnQ80Y/nEI3t/jvyK0Z8= X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20230601; t=1729606854; x=1730211654; h=content-transfer-encoding:in-reply-to:autocrypt:from :content-language:references:cc:to:subject:user-agent:mime-version :date:message-id:x-gm-message-state:from:to:cc:subject:date :message-id:reply-to; bh=3f3pXqNyI+bwOtKt5dUl7KO7hRUU1R9j1/G49d53U6A=; b=dl7K2Fa/l0Vj7vhIf57T4eeEQ7RCZqMo+UNSlfRN2nojByYGL7NCjHrbbgT1pOUGqX JOMMWsNKewj/0/hA4BNGpmxO9ml44T72Nain7EYPBybLWF3QdBZVrF31hj6hCqbqhpax lVJAhpP1d51RqwF6uTCzW3OsTef++0cwHx98QdeUEAo5V6C5xgnTGBtEzCgUi7cjLsM7 gxwOAEmzfhCYEi+73reuynwG4glR+M3zNoYAckBErgvAjrrNjFEMNJp5rcx9AVcHOv+A xrHAxRZhpkEnNCOemV8COX7YjxLtenDnotH+qzNkY60+P82EDyUr/FxZJUfqbaTSZt7I mSRg== X-Gm-Message-State: AOJu0YyxWv/oHIkgesH6728ufcSF9r0rP3QGOv2+9Z2DGFy3JVaA3f3J S5ylEZPF1+3aU022Uq+5jy0daQEWu2WLfbRxNV/vhRK58xnX8Cu40HOhxag5vRg= X-Google-Smtp-Source: AGHT+IEvOl91P9RM15RtFys8ueGxh/rArnfJRHUdg0YzGtzn3WMYarRUG4gApY2nf2z8vC4Av45GJQ== X-Received: by 2002:a2e:1309:0:b0:2f3:b71a:1e91 with SMTP id 38308e7fff4ca-2fc90541af3mr17989571fa.17.1729606853595; Tue, 22 Oct 2024 07:20:53 -0700 (PDT) Message-ID: <0273bc68-855d-4833-8c2f-ad9ff845c92b@citrix.com> Date: Tue, 22 Oct 2024 15:20:51 +0100 MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH] x86/boot: Fix PVH boot during boot_info transition period To: =?UTF-8?Q?Roger_Pau_Monn=C3=A9?= Cc: Xen-devel , Jan Beulich , "Daniel P . Smith" References: <20241022124114.84498-1-andrew.cooper3@citrix.com> Content-Language: en-GB From: Andrew Cooper Autocrypt: addr=andrew.cooper3@citrix.com; keydata= xsFNBFLhNn8BEADVhE+Hb8i0GV6mihnnr/uiQQdPF8kUoFzCOPXkf7jQ5sLYeJa0cQi6Penp VtiFYznTairnVsN5J+ujSTIb+OlMSJUWV4opS7WVNnxHbFTPYZVQ3erv7NKc2iVizCRZ2Kxn srM1oPXWRic8BIAdYOKOloF2300SL/bIpeD+x7h3w9B/qez7nOin5NzkxgFoaUeIal12pXSR Q354FKFoy6Vh96gc4VRqte3jw8mPuJQpfws+Pb+swvSf/i1q1+1I4jsRQQh2m6OTADHIqg2E ofTYAEh7R5HfPx0EXoEDMdRjOeKn8+vvkAwhviWXTHlG3R1QkbE5M/oywnZ83udJmi+lxjJ5 YhQ5IzomvJ16H0Bq+TLyVLO/VRksp1VR9HxCzItLNCS8PdpYYz5TC204ViycobYU65WMpzWe LFAGn8jSS25XIpqv0Y9k87dLbctKKA14Ifw2kq5OIVu2FuX+3i446JOa2vpCI9GcjCzi3oHV e00bzYiHMIl0FICrNJU0Kjho8pdo0m2uxkn6SYEpogAy9pnatUlO+erL4LqFUO7GXSdBRbw5 gNt25XTLdSFuZtMxkY3tq8MFss5QnjhehCVPEpE6y9ZjI4XB8ad1G4oBHVGK5LMsvg22PfMJ ISWFSHoF/B5+lHkCKWkFxZ0gZn33ju5n6/FOdEx4B8cMJt+cWwARAQABzSlBbmRyZXcgQ29v cGVyIDxhbmRyZXcuY29vcGVyM0BjaXRyaXguY29tPsLBegQTAQgAJAIbAwULCQgHAwUVCgkI CwUWAgMBAAIeAQIXgAUCWKD95wIZAQAKCRBlw/kGpdefoHbdD/9AIoR3k6fKl+RFiFpyAhvO 59ttDFI7nIAnlYngev2XUR3acFElJATHSDO0ju+hqWqAb8kVijXLops0gOfqt3VPZq9cuHlh IMDquatGLzAadfFx2eQYIYT+FYuMoPZy/aTUazmJIDVxP7L383grjIkn+7tAv+qeDfE+txL4 SAm1UHNvmdfgL2/lcmL3xRh7sub3nJilM93RWX1Pe5LBSDXO45uzCGEdst6uSlzYR/MEr+5Z JQQ32JV64zwvf/aKaagSQSQMYNX9JFgfZ3TKWC1KJQbX5ssoX/5hNLqxMcZV3TN7kU8I3kjK mPec9+1nECOjjJSO/h4P0sBZyIUGfguwzhEeGf4sMCuSEM4xjCnwiBwftR17sr0spYcOpqET ZGcAmyYcNjy6CYadNCnfR40vhhWuCfNCBzWnUW0lFoo12wb0YnzoOLjvfD6OL3JjIUJNOmJy RCsJ5IA/Iz33RhSVRmROu+TztwuThClw63g7+hoyewv7BemKyuU6FTVhjjW+XUWmS/FzknSi dAG+insr0746cTPpSkGl3KAXeWDGJzve7/SBBfyznWCMGaf8E2P1oOdIZRxHgWj0zNr1+ooF /PzgLPiCI4OMUttTlEKChgbUTQ+5o0P080JojqfXwbPAyumbaYcQNiH1/xYbJdOFSiBv9rpt TQTBLzDKXok86M7BTQRS4TZ/ARAAkgqudHsp+hd82UVkvgnlqZjzz2vyrYfz7bkPtXaGb9H4 Rfo7mQsEQavEBdWWjbga6eMnDqtu+FC+qeTGYebToxEyp2lKDSoAsvt8w82tIlP/EbmRbDVn 7bhjBlfRcFjVYw8uVDPptT0TV47vpoCVkTwcyb6OltJrvg/QzV9f07DJswuda1JH3/qvYu0p vjPnYvCq4NsqY2XSdAJ02HrdYPFtNyPEntu1n1KK+gJrstjtw7KsZ4ygXYrsm/oCBiVW/OgU g/XIlGErkrxe4vQvJyVwg6YH653YTX5hLLUEL1NS4TCo47RP+wi6y+TnuAL36UtK/uFyEuPy wwrDVcC4cIFhYSfsO0BumEI65yu7a8aHbGfq2lW251UcoU48Z27ZUUZd2Dr6O/n8poQHbaTd 6bJJSjzGGHZVbRP9UQ3lkmkmc0+XCHmj5WhwNNYjgbbmML7y0fsJT5RgvefAIFfHBg7fTY/i kBEimoUsTEQz+N4hbKwo1hULfVxDJStE4sbPhjbsPCrlXf6W9CxSyQ0qmZ2bXsLQYRj2xqd1 bpA+1o1j2N4/au1R/uSiUFjewJdT/LX1EklKDcQwpk06Af/N7VZtSfEJeRV04unbsKVXWZAk uAJyDDKN99ziC0Wz5kcPyVD1HNf8bgaqGDzrv3TfYjwqayRFcMf7xJaL9xXedMcAEQEAAcLB XwQYAQgACQUCUuE2fwIbDAAKCRBlw/kGpdefoG4XEACD1Qf/er8EA7g23HMxYWd3FXHThrVQ HgiGdk5Yh632vjOm9L4sd/GCEACVQKjsu98e8o3ysitFlznEns5EAAXEbITrgKWXDDUWGYxd pnjj2u+GkVdsOAGk0kxczX6s+VRBhpbBI2PWnOsRJgU2n10PZ3mZD4Xu9kU2IXYmuW+e5KCA vTArRUdCrAtIa1k01sPipPPw6dfxx2e5asy21YOytzxuWFfJTGnVxZZSCyLUO83sh6OZhJkk b9rxL9wPmpN/t2IPaEKoAc0FTQZS36wAMOXkBh24PQ9gaLJvfPKpNzGD8XWR5HHF0NLIJhgg 4ZlEXQ2fVp3XrtocHqhu4UZR4koCijgB8sB7Tb0GCpwK+C4UePdFLfhKyRdSXuvY3AHJd4CP 4JzW0Bzq/WXY3XMOzUTYApGQpnUpdOmuQSfpV9MQO+/jo7r6yPbxT7CwRS5dcQPzUiuHLK9i nvjREdh84qycnx0/6dDroYhp0DFv4udxuAvt1h4wGwTPRQZerSm4xaYegEFusyhbZrI0U9tJ B8WrhBLXDiYlyJT6zOV2yZFuW47VrLsjYnHwn27hmxTC/7tvG3euCklmkn9Sl9IAKFu29RSo d5bD8kMSCYsTqtTfT6W4A3qHGvIDta3ptLYpIAOD2sY3GYq2nf3Bbzx81wZK14JdDDHUX2Rs 6+ahAA== In-Reply-To: Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit On 22/10/2024 3:12 pm, Roger Pau Monné wrote: > On Tue, Oct 22, 2024 at 01:41:14PM +0100, Andrew Cooper wrote: >> multiboot_fill_boot_info() taking the physical address of the multiboot_info >> structure leads to a subtle use-after-free on the PVH path, with rather less >> subtle fallout. >> >> The pointers used by __start_xen(), mbi and mod, are either: >> >> - MB: Directmap pointers into the trampoline, or >> - PVH: Xen pointers into .initdata, or >> - EFI: Directmap pointers into Xen. >> >> Critically, these either remain valid across move_xen() (MB, PVH), or rely on >> move_xen() being inhibited (EFI). >> >> The conversion to multiboot_fill_boot_info(), taking only mbi_p, makes the PVH >> path use directmap pointers into Xen, as well as move_xen() which invalidates >> said pointers. >> >> Switch multiboot_fill_boot_info() to consume the same virtual addresses that >> __start_xen() currently uses. This keeps all the pointers valid for the >> duration of __start_xen(), for all boot protocols. >> >> It can be safely untangled once multiboot_fill_boot_info() takes a full copy >> the multiboot info data, and __start_xen() has been moved over to using the >> new boot_info consistently. >> >> Right now, bi->{loader,cmdline,mods} are problematic. Nothing uses >> bi->mods[], and nothing uses bi->cmdline after move_xen(). >> >> bi->loader is used after move_xen(), although only for cmdline_cook() of >> dom0's cmdline, where it happens to be benign because PVH boot skips the >> inspection of the bootloader name. >> >> Signed-off-by: Andrew Cooper > Acked-by: Roger Pau Monné Thanks. > > One nit below about dropping a const keyword. > >> --- >> CC: Jan Beulich >> CC: Roger Pau Monné >> CC: Daniel P. Smith >> >> This is more proof that Xen only boots by accident. It certainly isn't by any >> kind of design. >> >> https://gitlab.com/xen-project/people/andyhhp/xen/-/pipelines/1506947472 >> including the pending work to add a PVShim test >> >> This is the least-invasive fix given the rest of the Hyperlaunch series. >> >> A different option would to introduce EFI and PVH forms of >> multiboot_fill_boot_info(), but that would involve juggling even more moving >> parts during the transition period. >> --- >> xen/arch/x86/setup.c | 25 ++++++++++++++++++++----- >> 1 file changed, 20 insertions(+), 5 deletions(-) >> >> diff --git a/xen/arch/x86/setup.c b/xen/arch/x86/setup.c >> index db670258d650..e43b56d4e80f 100644 >> --- a/xen/arch/x86/setup.c >> +++ b/xen/arch/x86/setup.c >> @@ -283,11 +283,10 @@ struct boot_info __initdata xen_boot_info = { >> .cmdline = "", >> }; >> >> -static struct boot_info *__init multiboot_fill_boot_info(unsigned long mbi_p) >> +static struct boot_info *__init multiboot_fill_boot_info( >> + multiboot_info_t *mbi, module_t *mods) > Shouldn't mbi keep the const keyword? Given there are no changes on > how it's used in multiboot_fill_boot_info(). Fine. FWIW, https://gitlab.com/xen-project/people/andyhhp/xen/-/pipelines/1507153249 is previously-crashing consider_modules() change, with this fix in place, shown now to be functioning. ~Andrew