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 95592C43334 for ; Thu, 14 Jul 2022 04:35:14 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S237532AbiGNEfM (ORCPT ); Thu, 14 Jul 2022 00:35:12 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:47482 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S237494AbiGNEeB (ORCPT ); Thu, 14 Jul 2022 00:34:01 -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 48BDB3AE5D; Wed, 13 Jul 2022 21:26:06 -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 CA5A5B82382; Thu, 14 Jul 2022 04:26:04 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id C44BAC385A2; Thu, 14 Jul 2022 04:26:01 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1657772763; bh=IY9obyUbaF68yfYZpMGSF3IiznXLM6j2my70GgvTAUE=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=gMe/b9J0KFWUc4DdFKcV0jrL4geiFkiah65aNQ+dq8n8rykwVI/hJZedhx71yaYTF BObSfV8oZvzyMO0qInDfnzsSrDcIX0JDfX3fB1fiSJA0Po2DiiRs8oNqmn40FHS5Rz lR1HExTElzi37Wc7twz6TF3cfiMt5u0a0BSGSlzm4/5SwsIxM7bGiIE+Mt3ywk+Em5 ZyE4FAOkjjx/8tpM/88GmjxvfXKiVamY7YCvht/+ee/GTHkJN5gUOzOGOR3a8v0NGg wQGFFyFSQCSxBFFkFz0pfRzGw2XoPAU0LqXA4164Qij71YJoMZf1e+n0QJSLEccv/k 7o+4eNGI50sog== 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, sathyanarayanan.kuppuswamy@linux.intel.com, ak@linux.intel.com, michael.roth@amd.com, jroedel@suse.de, thomas.lendacky@amd.com Subject: [PATCH AUTOSEL 5.10 10/15] x86: Clear .brk area at early boot Date: Thu, 14 Jul 2022 00:25:35 -0400 Message-Id: <20220714042541.282175-10-sashal@kernel.org> X-Mailer: git-send-email 2.35.1 In-Reply-To: <20220714042541.282175-1-sashal@kernel.org> References: <20220714042541.282175-1-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 05e117137b45..efe13ab366f4 100644 --- a/arch/x86/kernel/head64.c +++ b/arch/x86/kernel/head64.c @@ -419,6 +419,8 @@ 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