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 589EACCA487 for ; Thu, 14 Jul 2022 04:31:56 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S237465AbiGNEby (ORCPT ); Thu, 14 Jul 2022 00:31:54 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:35484 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S235609AbiGNEbB (ORCPT ); Thu, 14 Jul 2022 00:31:01 -0400 Received: from dfw.source.kernel.org (dfw.source.kernel.org [139.178.84.217]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 13F17326FC; Wed, 13 Jul 2022 21:25:18 -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 8970461E51; Thu, 14 Jul 2022 04:25:17 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id 73136C385A2; Thu, 14 Jul 2022 04:25:15 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1657772716; bh=GfEQxJNjjHPalvfvVNCj9R5BmsifevUz1PfOtOY//7E=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=pZeFwsauWXf1nKyRqjdtt9MoA7/Ryw2PbQ6C/8Nq3QCBH4cvd5Wh7hVtQs5ky4VPS cib4D+MonmxpPm5QIBf9zF5FCRYmVVQ2u1wHnG7LTory5b3m/996cY3xKmX4n2OZ0W zBuSz6+K84bHPjavlyhkH1fYxNzTVIWKmTnQys2euCWRyGBvdpSNsBYa+M4uPA6lTo 2Irq6sQczA1ZPyM24f3qo1eQTo/QIZO9fSCQIxOy/FZHfD+XJa0jrQH/4xNwf9w0Y/ qVtDZ5OKZj/bwUkqBqD8rd7tnuHpydBcaMkKU9XdzvhgK0Ay7rbzC7p0bVIcHczRpp SHT8I+8RHGNdQ== 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, michael.roth@amd.com, marco@mebeim.net, thomas.lendacky@amd.com Subject: [PATCH AUTOSEL 5.15 20/28] x86: Clear .brk area at early boot Date: Thu, 14 Jul 2022 00:24:21 -0400 Message-Id: <20220714042429.281816-20-sashal@kernel.org> X-Mailer: git-send-email 2.35.1 In-Reply-To: <20220714042429.281816-1-sashal@kernel.org> References: <20220714042429.281816-1-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 de01903c3735..5036104d5470 100644 --- a/arch/x86/kernel/head64.c +++ b/arch/x86/kernel/head64.c @@ -418,6 +418,8 @@ 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