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=-6.8 required=3.0 tests=DKIMWL_WL_HIGH,DKIM_SIGNED, DKIM_VALID,HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SIGNED_OFF_BY, SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED,USER_AGENT_GIT autolearn=unavailable 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 4A6F7C433E0 for ; Fri, 19 Jun 2020 16:39:57 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 18B7A20809 for ; Fri, 19 Jun 2020 16:39:57 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1592584797; bh=97KhVImh3fMbPEhCdHz6ESrRxmRllU7uaOXxayOKOV8=; h=From:To:Cc:Subject:Date:In-Reply-To:References:List-ID:From; b=UkQlJEBLV8ZaL1CQ4q0cPqHliabSqA6VwCAumbOG0PMjuF0vGUxJDYPXQis/pX/Mw C1R16rBXjf9q6bGBLPV4zC09Fy+HQj848Kxa22xY3pcdQd0XfelFmi/rV9sLwknoqk FDsX12/y3M2wSmG/OnvAIHbXlji73vhGhArFXSq0= Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S2388809AbgFSOqL (ORCPT ); Fri, 19 Jun 2020 10:46:11 -0400 Received: from mail.kernel.org ([198.145.29.99]:37722 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S2388787AbgFSOqC (ORCPT ); Fri, 19 Jun 2020 10:46:02 -0400 Received: from localhost (83-86-89-107.cable.dynamic.v4.ziggo.nl [83.86.89.107]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPSA id 924F92083B; Fri, 19 Jun 2020 14:46:01 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1592577962; bh=97KhVImh3fMbPEhCdHz6ESrRxmRllU7uaOXxayOKOV8=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=lzp+XAKHH39Jp+HmviDVl8J2GtQEmQDk1bkQsmrcnkPc7hPTdP+VlZECbEaFF/49C lCPWtvMSiM27Ap+CRziGUJyFxBe9NmrwMFYyejw7tDj11lJtEbtc70yOv3ymMSsobr DXeaA5pw8Ralx3CWdkbnU6KTn48dPFF/TUYqVkOI= From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, Julien Thierry , Will Deacon , Linus Torvalds , Miles Chen Subject: [PATCH 4.14 006/190] x86: uaccess: Inhibit speculation past access_ok() in user_access_begin() Date: Fri, 19 Jun 2020 16:30:51 +0200 Message-Id: <20200619141633.788051361@linuxfoundation.org> X-Mailer: git-send-email 2.27.0 In-Reply-To: <20200619141633.446429600@linuxfoundation.org> References: <20200619141633.446429600@linuxfoundation.org> User-Agent: quilt/0.66 MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org From: Will Deacon commit 6e693b3ffecb0b478c7050b44a4842854154f715 upstream. Commit 594cc251fdd0 ("make 'user_access_begin()' do 'access_ok()'") makes the access_ok() check part of the user_access_begin() preceding a series of 'unsafe' accesses. This has the desirable effect of ensuring that all 'unsafe' accesses have been range-checked, without having to pick through all of the callsites to verify whether the appropriate checking has been made. However, the consolidated range check does not inhibit speculation, so it is still up to the caller to ensure that they are not susceptible to any speculative side-channel attacks for user addresses that ultimately fail the access_ok() check. This is an oversight, so use __uaccess_begin_nospec() to ensure that speculation is inhibited until the access_ok() check has passed. Reported-by: Julien Thierry Signed-off-by: Will Deacon Signed-off-by: Linus Torvalds Cc: Miles Chen Signed-off-by: Greg Kroah-Hartman --- arch/x86/include/asm/uaccess.h | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) --- a/arch/x86/include/asm/uaccess.h +++ b/arch/x86/include/asm/uaccess.h @@ -717,7 +717,7 @@ static __must_check inline bool user_acc { if (unlikely(!access_ok(type, ptr, len))) return 0; - __uaccess_begin(); + __uaccess_begin_nospec(); return 1; }