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 2398BC433EF for ; Thu, 14 Jul 2022 04:38:39 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S237031AbiGNEig (ORCPT ); Thu, 14 Jul 2022 00:38:36 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:46940 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S234296AbiGNEhj (ORCPT ); Thu, 14 Jul 2022 00:37:39 -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 D6E771A81E; Wed, 13 Jul 2022 21:27:06 -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 8867EB82376; Thu, 14 Jul 2022 04:27:05 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id 85A16C34114; Thu, 14 Jul 2022 04:27:02 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1657772824; bh=4fuDo9GyeOb4vTdduQvEyIq7rIyMwxLnhvLNqWOmU98=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=V2ljjy1oD+zxOGckcDl7YTVuuuetpHX7soZ//vBJ7l+/fYkclzTHu7Tf1P3A0CVnu ZFVmAA64s9KDw0ev+ePF4EJz1wOsy9/utflWhK0u7YhnBFaoGxOLxVLQU/WfkidBzv ReL3tJHB1bg3fm7caNb/9Oi6f4spUibLlkgUtlk13XF7QHeQaVeRbtm4sFL2ntzHS8 sCsY0E264fr5kUXsojj8caF2F7vtWlszDpNkhlMq+WCfBYkvUZtUvuCmXq0+FrymrN rMktEzyZjl6eQifXMOwOVARU/0Rm4yNMwdyEwB7fO+gYmky/0p9JTeX8hjD3iVlbfh VS5hCBcjOATwg== 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, kirill.shutemov@linux.intel.com, michael.roth@amd.com, sathyanarayanan.kuppuswamy@linux.intel.com, thomas.lendacky@amd.com Subject: [PATCH AUTOSEL 4.14 4/5] x86: Clear .brk area at early boot Date: Thu, 14 Jul 2022 00:26:51 -0400 Message-Id: <20220714042653.282599-4-sashal@kernel.org> X-Mailer: git-send-email 2.35.1 In-Reply-To: <20220714042653.282599-1-sashal@kernel.org> References: <20220714042653.282599-1-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 e00ccbcc2913..59aa1d0646e4 100644 --- a/arch/x86/kernel/head64.c +++ b/arch/x86/kernel/head64.c @@ -292,6 +292,8 @@ 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