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 93CD2C433EF for ; Thu, 14 Jul 2022 04:37:49 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S237682AbiGNEhs (ORCPT ); Thu, 14 Jul 2022 00:37:48 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:46942 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S236983AbiGNEhF (ORCPT ); Thu, 14 Jul 2022 00:37:05 -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 1C7873D5BE; Wed, 13 Jul 2022 21:26:51 -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 77B9DB82372; Thu, 14 Jul 2022 04:26:49 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id 7D17DC36AE3; Thu, 14 Jul 2022 04:26:46 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1657772808; bh=hkNBwUYHFKGSvzmtLsoGiokgbvyoXmsQTklyeIXqUZs=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=ddpqq2m4chTwUDegnqG0zeQRSyWX6Dhg5ioC2mngwHzCsr7yvmmrOOgxVh6R+X6Lc 0ME1+UcYIUhcMQtNxtFCmhIuAxEyJ99AZLY7gYxj34pqfOe+MISO/M9Dq63t77x10B 26YLJT2rOABGI2V7zr23cqyqLpuWWhfK4+gErNceB1m6WEzo+ct+xryyj5jgWyIAQn ZhIRttgsr1Y2rH4gmih8rdNZLpbLL0HHlE+F2wqoXW0SrTKHZ3EytsWrG7sp0DVw3k PZRfaolV2eDi9e3W17c5w6yjAxSDl7I+yOy5m2UZzGaIJVClS4fMg6gVjFWurA1n8J LwRQxhprK7R8w== 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, ak@linux.intel.com, michael.roth@amd.com, marco@mebeim.net, thomas.lendacky@amd.com Subject: [PATCH AUTOSEL 4.19 4/6] x86: Clear .brk area at early boot Date: Thu, 14 Jul 2022 00:26:34 -0400 Message-Id: <20220714042637.282511-4-sashal@kernel.org> X-Mailer: git-send-email 2.35.1 In-Reply-To: <20220714042637.282511-1-sashal@kernel.org> References: <20220714042637.282511-1-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 88dc38b4a147..90c2613af36b 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