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 X-Spam-Level: X-Spam-Status: No, score=-10.1 required=3.0 tests=DKIMWL_WL_HIGH,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY, SPF_HELO_NONE,SPF_PASS,USER_AGENT_GIT autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 4CAC5FA372C for ; Fri, 8 Nov 2019 12:37:17 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 194E8222CE for ; Fri, 8 Nov 2019 12:37:17 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1573216637; bh=SDbaNArifCOVOaGG+5t8JrDRJ/7O8VsQSUvVbSfNrfA=; h=From:To:Cc:Subject:Date:In-Reply-To:References:List-ID:From; b=Reliw+MrM8CCpm8XWkFGTKdbk5IjEj2aKnMkooOgiJaEPgnTQXK25dtqvWouQMn02 RAIsGe00LWwgVvtvUPTHTlXrDVSQyTDX5yqs7vhs5F22JEmVEVZofxweR5/R2g+ERQ oTI0t0OuxkgdIWyRQbhSJ8atVhqpkj1eObylKffY= Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727159AbfKHMhQ (ORCPT ); Fri, 8 Nov 2019 07:37:16 -0500 Received: from mail.kernel.org ([198.145.29.99]:44898 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1727044AbfKHMhQ (ORCPT ); Fri, 8 Nov 2019 07:37:16 -0500 Received: from localhost.localdomain (lfbn-mar-1-550-151.w90-118.abo.wanadoo.fr [90.118.131.151]) (using TLSv1.2 with cipher ECDHE-RSA-AES128-GCM-SHA256 (128/128 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPSA id 960432245A; Fri, 8 Nov 2019 12:37:14 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1573216635; bh=SDbaNArifCOVOaGG+5t8JrDRJ/7O8VsQSUvVbSfNrfA=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=yvCfHgzi3sMznpCC25OlXu+kczWCKlFJ97JZI0xdUFFdKcAy2NU5O52IFwlekbCIV 41JyE7DlQqPlyc9nUSMs7MyrpmvFdsefgCK1g3HelDcRw5ov1Lqb3Pz8fEPlxQIBSh dbmlODXCkJU1BNf7rCbWmRBT7pxx48D4A3CK3sg8= From: Ard Biesheuvel To: stable@vger.kernel.org Cc: linus.walleij@linaro.org, rmk+kernel@armlinux.org.uk, Julien Thierry , Ard Biesheuvel Subject: [PATCH for-stable-4.4 40/50] ARM: 8794/1: uaccess: Prevent speculative use of the current addr_limit Date: Fri, 8 Nov 2019 13:35:44 +0100 Message-Id: <20191108123554.29004-41-ardb@kernel.org> X-Mailer: git-send-email 2.20.1 In-Reply-To: <20191108123554.29004-1-ardb@kernel.org> References: <20191108123554.29004-1-ardb@kernel.org> MIME-Version: 1.0 Content-Transfer-Encoding: 8bit Sender: stable-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: stable@vger.kernel.org From: Julien Thierry Commit 621afc677465db231662ed126ae1f355bf8eac47 upstream. A mispredicted conditional call to set_fs could result in the wrong addr_limit being forwarded under speculation to a subsequent access_ok check, potentially forming part of a spectre-v1 attack using uaccess routines. This patch prevents this forwarding from taking place, but putting heavy barriers in set_fs after writing the addr_limit. Porting commit c2f0ad4fc089cff8 ("arm64: uaccess: Prevent speculative use of the current addr_limit"). Signed-off-by: Julien Thierry Signed-off-by: Russell King Signed-off-by: David A. Long Reviewed-by: Julien Thierry Signed-off-by: Sasha Levin Signed-off-by: Ard Biesheuvel --- arch/arm/include/asm/uaccess.h | 8 ++++++++ 1 file changed, 8 insertions(+) diff --git a/arch/arm/include/asm/uaccess.h b/arch/arm/include/asm/uaccess.h index fd33021da6f6..0404dd101331 100644 --- a/arch/arm/include/asm/uaccess.h +++ b/arch/arm/include/asm/uaccess.h @@ -99,6 +99,14 @@ extern int __put_user_bad(void); static inline void set_fs(mm_segment_t fs) { current_thread_info()->addr_limit = fs; + + /* + * Prevent a mispredicted conditional call to set_fs from forwarding + * the wrong address limit to access_ok under speculation. + */ + dsb(nsh); + isb(); + modify_domain(DOMAIN_KERNEL, fs ? DOMAIN_CLIENT : DOMAIN_MANAGER); } -- 2.20.1