From nobody Sun Apr 19 10:43:39 2026 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 79E8AC433EF for ; Sat, 2 Jul 2022 09:54:38 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S232214AbiGBJyg (ORCPT ); Sat, 2 Jul 2022 05:54:36 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:57004 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S232122AbiGBJyb (ORCPT ); Sat, 2 Jul 2022 05:54:31 -0400 Received: from galois.linutronix.de (Galois.linutronix.de [193.142.43.55]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 7EFD117A97; Sat, 2 Jul 2022 02:54:30 -0700 (PDT) Date: Sat, 02 Jul 2022 09:54:27 -0000 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linutronix.de; s=2020; t=1656755668; h=from:from:sender:sender:reply-to:reply-to:subject:subject:date:date: message-id:message-id:to:to:cc:cc:mime-version:mime-version: content-type:content-type: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=PKApq4U1SQ86Vmc/jq0O6mKSJtDk9jWeFmLcPOmEbmM=; b=xv4TaJvMxH+vtkYw6BFuII2pceQ1QdF5NWXmwzXgIdrD3AU0uTvdKaY6C+odX9eLsZqpc7 YSF1MyTCDY+2CM4H62laGskWoTtZt//fforr4qmoV3YK6yrn3S+4PHJE2RcuFpm5JmZSpr wYKEXTq/niIxWFkm1gavbUZKySXbVdo4+BQdR92/DFKXONDLr+jWVgCuwQtqvqOL82zWvK ctRe+qrl6Xnz9f7kxuRYvV01U2L6/cvegz/tq9YvCPEA9i075jYxWvwQ4447tl9KGieFXA oEK7ZdqYy8eshF/mh24oDEeDEfluQJtds0ZP5vaCREIEsREgZpehQSPUtX7/eA== DKIM-Signature: v=1; a=ed25519-sha256; c=relaxed/relaxed; d=linutronix.de; s=2020e; t=1656755668; h=from:from:sender:sender:reply-to:reply-to:subject:subject:date:date: message-id:message-id:to:to:cc:cc:mime-version:mime-version: content-type:content-type: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=PKApq4U1SQ86Vmc/jq0O6mKSJtDk9jWeFmLcPOmEbmM=; b=VrUOUS87Blm5I8kDv5Ru611XqIujlLcaU64GErokJc3rbFBf/hEF9o3cYRCKKHBQI06bph XtaTfzOCnddqalAg== From: "tip-bot2 for Juergen Gross" Sender: tip-bot2@linutronix.de Reply-to: linux-kernel@vger.kernel.org To: linux-tip-commits@vger.kernel.org Subject: [tip: x86/urgent] x86: Clear .brk area at early boot Cc: Juergen Gross , Borislav Petkov , x86@kernel.org, linux-kernel@vger.kernel.org In-Reply-To: <20220630071441.28576-3-jgross@suse.com> References: <20220630071441.28576-3-jgross@suse.com> MIME-Version: 1.0 Message-ID: <165675566764.15455.13299455113008964537.tip-bot2@tip-bot2> Robot-ID: Robot-Unsubscribe: Contact to get blacklisted from these emails Content-Type: text/plain; charset="utf-8" Content-Transfer-Encoding: quoted-printable Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org The following commit has been merged into the x86/urgent branch of tip: Commit-ID: 38fa5479b41376dc9d7f57e71c83514285a25ca0 Gitweb: https://git.kernel.org/tip/38fa5479b41376dc9d7f57e71c8351428= 5a25ca0 Author: Juergen Gross AuthorDate: Thu, 30 Jun 2022 09:14:40 +02:00 Committer: Borislav Petkov CommitterDate: Fri, 01 Jul 2022 11:11:34 +02:00 x86: Clear .brk area at early boot 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 --- 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 e7e2332..6a3cfaf 100644 --- a/arch/x86/kernel/head64.c +++ b/arch/x86/kernel/head64.c @@ -430,6 +430,8 @@ 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); } =20 static unsigned long get_cmd_line_ptr(void)