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 86927C433EF for ; Tue, 19 Jul 2022 13:13:18 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S243336AbiGSNNR (ORCPT ); Tue, 19 Jul 2022 09:13:17 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:55434 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S243313AbiGSNMM (ORCPT ); Tue, 19 Jul 2022 09:12:12 -0400 Received: from dfw.source.kernel.org (dfw.source.kernel.org [IPv6:2604:1380:4641:c500::1]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 58BE8419B9; Tue, 19 Jul 2022 05:29:45 -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 E392B60DE0; Tue, 19 Jul 2022 12:29:44 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id BF68FC341C6; Tue, 19 Jul 2022 12:29:43 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1658233784; bh=1rsOjCzTzZZGjsOkD4VV/Yi0b4wpzhVrNjevvk3ABTM=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=B7YiVPHPq+/BIewCuIuothP172iHYQpS4WpgY+BiRyEsPrZrSHoWvDxhgtaHGzrWO JLjif9vG2qINdlggH3PF8/eDELsTQ+/OGgkeWqdrWPI3Jxft/90t4J9JdDmrln+8wt WwzzNjxzkpYsugtuThhxPb6IxQres3zz6d/05xOQ= From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, Juergen Gross , Borislav Petkov , Sasha Levin Subject: [PATCH 5.18 209/231] x86: Clear .brk area at early boot Date: Tue, 19 Jul 2022 13:54:54 +0200 Message-Id: <20220719114731.488525670@linuxfoundation.org> X-Mailer: git-send-email 2.37.1 In-Reply-To: <20220719114714.247441733@linuxfoundation.org> References: <20220719114714.247441733@linuxfoundation.org> User-Agent: quilt/0.66 MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 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 2e10a33778cf..92eae95f1a0b 100644 --- a/arch/x86/kernel/head64.c +++ b/arch/x86/kernel/head64.c @@ -425,6 +425,8 @@ 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