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 12D5CC43334 for ; Thu, 14 Jul 2022 04:36:52 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S232095AbiGNEgt (ORCPT ); Thu, 14 Jul 2022 00:36:49 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:46048 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S237661AbiGNEf6 (ORCPT ); Thu, 14 Jul 2022 00:35:58 -0400 Received: from dfw.source.kernel.org (dfw.source.kernel.org [139.178.84.217]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 1845C3CBDC; Wed, 13 Jul 2022 21:26:31 -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 dfw.source.kernel.org (Postfix) with ESMTPS id D3B2E61E51; Thu, 14 Jul 2022 04:26:30 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id 6D126C34114; Thu, 14 Jul 2022 04:26:28 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1657772790; bh=aCxKvGgvHIIyXlj7KbS97sr9G2YeS9r+HloRo3tKYo4=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=QQSe6ajwBtw+5pe0FOMGkLDiy0JVhbbbCpr7AVaC5umztEkQDAvAsZ7n56RHWm12f 7Yc+on5as0ansPQK2/cAhKKZYGqxbgJvrsCwbqwoWu3KqBCWgdVWgCb3u+8nsaPENl 3X/wRjDBk5URiz7+k4UQyW/FanMsv8wr/zqSCrHMEUn30mSXwfAAN7SgQ6Sf98P+Bx VRcAkjAGfWcrzEYBtZRWcCLncS5sDT2P5wFKohem4iv6rNs7HLSZP7PYB6bFInYxOG wDFVbTRmsxukxpEuwCB9aESUoljdBw5QQP019pIkphs/KevftdCEPhidEEXX1LIrFw 4YRp/YXY2JeTA== 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, ak@linux.intel.com, kirill.shutemov@linux.intel.com, michael.roth@amd.com, sathyanarayanan.kuppuswamy@linux.intel.com, thomas.lendacky@amd.com Subject: [PATCH AUTOSEL 5.4 07/10] x86: Clear .brk area at early boot Date: Thu, 14 Jul 2022 00:26:09 -0400 Message-Id: <20220714042612.282378-7-sashal@kernel.org> X-Mailer: git-send-email 2.35.1 In-Reply-To: <20220714042612.282378-1-sashal@kernel.org> References: <20220714042612.282378-1-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 206a4b6144c2..950286016f63 100644 --- a/arch/x86/kernel/head64.c +++ b/arch/x86/kernel/head64.c @@ -383,6 +383,8 @@ 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