From patchwork Tue Sep 6 11:27:19 2022 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-Patchwork-Submitter: "Jason A. Donenfeld" X-Patchwork-Id: 12967374 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.gnu.org (lists.gnu.org [209.51.188.17]) (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 0A479C54EE9 for ; Tue, 6 Sep 2022 12:12:57 +0000 (UTC) Received: from localhost ([::1]:46994 helo=lists1p.gnu.org) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1oVXRo-00045i-62 for qemu-devel@archiver.kernel.org; Tue, 06 Sep 2022 08:12:56 -0400 Received: from eggs.gnu.org ([2001:470:142:3::10]:52050) by lists.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1oVWjw-0007uP-Pj for qemu-devel@nongnu.org; Tue, 06 Sep 2022 07:27:36 -0400 Received: from dfw.source.kernel.org ([2604:1380:4641:c500::1]:51468) by eggs.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1oVWju-0001Uy-FK for qemu-devel@nongnu.org; Tue, 06 Sep 2022 07:27:36 -0400 Received: from smtp.kernel.org (relay.kernel.org [52.25.139.140]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by dfw.source.kernel.org (Postfix) with ESMTPS id 93FF360EDF; Tue, 6 Sep 2022 11:27:32 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id 18074C433C1; Tue, 6 Sep 2022 11:27:31 +0000 (UTC) Authentication-Results: smtp.kernel.org; dkim=pass (1024-bit key) header.d=zx2c4.com header.i=@zx2c4.com header.b="UalZnmN5" DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=zx2c4.com; s=20210105; t=1662463648; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version:content-type:content-type: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=i+ork0NWYelhpUJH59zxJVPX87EnVj/k4lofQfUOJss=; b=UalZnmN5JxemeO9m/kL/eoKdQWR7ObxBcocnkUWxcqyZVMfuYG9r6ozw+scGPPqf0GJ3Aw Z7TuEoD3W9L1VAn3mtSxLUS+azh4E3/vB8N68UH5VFzRSqEHRriuKePlaPG5ay0vNpIIJ8 K9t0Pyb6HkwefHoGyvYMREJZpliwK0c= Received: by mail.zx2c4.com (ZX2C4 Mail Server) with ESMTPSA id 9796e1ac (TLSv1.3:TLS_AES_256_GCM_SHA384:256:NO); Tue, 6 Sep 2022 11:27:28 +0000 (UTC) From: "Jason A. Donenfeld" To: qemu-devel@nongnu.org Cc: "Jason A. Donenfeld" , Laurent Vivier , "Michael S . Tsirkin" , Paolo Bonzini , Peter Maydell , =?utf-8?q?Philippe_Mathieu-Daud?= =?utf-8?q?=C3=A9?= , Richard Henderson , Ard Biesheuvel , Gerd Hoffmann Subject: [PATCH v3 1/2] x86: only modify setup_data if the boot protocol indicates safety Date: Tue, 6 Sep 2022 13:27:19 +0200 Message-Id: <20220906112720.292836-1-Jason@zx2c4.com> In-Reply-To: References: MIME-Version: 1.0 Received-SPF: pass client-ip=2604:1380:4641:c500::1; envelope-from=SRS0=X/Hh=ZJ=zx2c4.com=Jason@kernel.org; helo=dfw.source.kernel.org X-Spam_score_int: -67 X-Spam_score: -6.8 X-Spam_bar: ------ X-Spam_report: (-6.8 / 5.0 requ) BAYES_00=-1.9, DKIM_SIGNED=0.1, DKIM_VALID=-0.1, DKIM_VALID_AU=-0.1, HEADER_FROM_DIFFERENT_DOMAINS=0.25, RCVD_IN_DNSWL_HI=-5, SPF_HELO_NONE=0.001, SPF_PASS=-0.001, T_SCC_BODY_TEXT_LINE=-0.01 autolearn=ham autolearn_force=no X-Spam_action: no action X-BeenThere: qemu-devel@nongnu.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Sender: "Qemu-devel" It's only safe to modify the setup_data pointer on newer kernels where the EFI stub loader will ignore it. So condition setting that offset on the newer boot protocol version. Cc: Laurent Vivier Cc: Michael S. Tsirkin Cc: Paolo Bonzini Cc: Peter Maydell Cc: Philippe Mathieu-Daudé Cc: Richard Henderson Cc: Ard Biesheuvel Link: https://lore.kernel.org/linux-efi/20220904165321.1140894-1-Jason@zx2c4.com/ Acked-by: Gerd Hoffmann Signed-off-by: Jason A. Donenfeld --- hw/i386/x86.c | 10 ++++++++-- 1 file changed, 8 insertions(+), 2 deletions(-) diff --git a/hw/i386/x86.c b/hw/i386/x86.c index 050eedc0c8..0c355c29b4 100644 --- a/hw/i386/x86.c +++ b/hw/i386/x86.c @@ -1088,8 +1088,14 @@ void x86_load_linux(X86MachineState *x86ms, qemu_guest_getrandom_nofail(setup_data->data, RNG_SEED_LENGTH); } - /* Offset 0x250 is a pointer to the first setup_data link. */ - stq_p(header + 0x250, first_setup_data); + /* + * Only modify the header if doing so won't crash EFI boot, which is the + * case only for newer boot protocols. + */ + if (protocol >= 0x210) { + /* Offset 0x250 is a pointer to the first setup_data link. */ + stq_p(header + 0x250, first_setup_data); + } /* * If we're starting an encrypted VM, it will be OVMF based, which uses the