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 3A3A9CCA482 for ; Thu, 14 Jul 2022 04:39:47 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S232171AbiGNEjo (ORCPT ); Thu, 14 Jul 2022 00:39:44 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:48276 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S237556AbiGNEiY (ORCPT ); Thu, 14 Jul 2022 00:38:24 -0400 Received: from ams.source.kernel.org (ams.source.kernel.org [IPv6:2604:1380:4601:e00::1]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 4770F3ED77; Wed, 13 Jul 2022 21:27:20 -0700 (PDT) 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 ams.source.kernel.org (Postfix) with ESMTPS id C47EBB8237C; Thu, 14 Jul 2022 04:27:18 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id DAF15C34115; Thu, 14 Jul 2022 04:27:15 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1657772837; bh=JvbAeAtnbcUPKYYQMBpl0nkK9xZaQTNviOPQ5mXGdFI=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=L3jrtXPnvRsC4TsdatlT8NS1Rz80P2gbTLT+JPlDfRtqu2C98AQgAuFo+LQ58kKfy 0h4/bFJ/1tf5zCSvOnKybgRHrzqEI1TubGMNmsBNFz/b2qchvwDyaKniAVKgcr/Zf/ uO+gMYIWUMGb5hJBZoE18VuoKxPIKtGUJ34niYlOeTcsOcSI+CuYj+NSESbNnDSfTm HWLLUPYiULHLP019r6lMSKpcCyST8PPCjuPOOypqBmtiC/FXk4Xoph39oeR/+ToKIk 4L391SVOKMOQ4mGRQtZ5BvUgtWUzqOpBPMTMWZIaOUPkxRk5gbuyF8et1ZjMT2lHK/ TGhySXHEEOuLg== From: Sasha Levin To: linux-kernel@vger.kernel.org, stable@vger.kernel.org Cc: Juergen Gross , Borislav Petkov , Sasha Levin , tglx@linutronix.de, mingo@redhat.com, bp@alien8.de, dave.hansen@linux.intel.com, x86@kernel.org, brijesh.singh@amd.com, michael.roth@amd.com, ak@linux.intel.com, thomas.lendacky@amd.com Subject: [PATCH AUTOSEL 4.9 3/4] x86: Clear .brk area at early boot Date: Thu, 14 Jul 2022 00:27:06 -0400 Message-Id: <20220714042707.282675-3-sashal@kernel.org> X-Mailer: git-send-email 2.35.1 In-Reply-To: <20220714042707.282675-1-sashal@kernel.org> References: <20220714042707.282675-1-sashal@kernel.org> MIME-Version: 1.0 X-stable: review X-Patchwork-Hint: Ignore Content-Transfer-Encoding: 8bit Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org From: Juergen Gross [ Upstream commit 38fa5479b41376dc9d7f57e71c83514285a25ca0 ] The .brk section has the same properties as .bss: it is an alloc-only section and should be cleared before being used. Not doing so is especially a problem for Xen PV guests, as the hypervisor will validate page tables (check for writable page tables and hypervisor private bits) before accepting them to be used. Make sure .brk is initially zero by letting clear_bss() clear the brk area, too. Signed-off-by: Juergen Gross Signed-off-by: Borislav Petkov Link: https://lore.kernel.org/r/20220630071441.28576-3-jgross@suse.com Signed-off-by: Sasha Levin --- arch/x86/kernel/head64.c | 2 ++ 1 file changed, 2 insertions(+) diff --git a/arch/x86/kernel/head64.c b/arch/x86/kernel/head64.c index b5785c197e53..2b2060d842d1 100644 --- a/arch/x86/kernel/head64.c +++ b/arch/x86/kernel/head64.c @@ -106,6 +106,8 @@ static void __init clear_bss(void) { memset(__bss_start, 0, (unsigned long) __bss_stop - (unsigned long) __bss_start); + memset(__brk_base, 0, + (unsigned long) __brk_limit - (unsigned long) __brk_base); } static unsigned long get_cmd_line_ptr(void) -- 2.35.1