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 D66FAC433E0 for ; Mon, 18 May 2020 18:07:37 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id B947820826 for ; Mon, 18 May 2020 18:07:37 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1589825257; bh=dauGskwhFdS0FQcA5fjSQecXpT+n6+sjzPuDZ4Qa8pM=; h=From:To:Cc:Subject:Date:In-Reply-To:References:List-ID:From; b=wk5QNENqgX3ve66+az+9JHWxydjvhdZSkGXltJuO6FVHpvdtDTIY9703fjSQTO79d 280AJFxXiuc5GKUwriTJkKDcdwDinYJE20rSS7mqeAXJlZgkWQYbXuVUpeJ9/aawTM vNVYl2Q8PIF/r69JLFUkuE4q6l4VW+HXjuexj6bc= Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S2387422AbgERSHh (ORCPT ); Mon, 18 May 2020 14:07:37 -0400 Received: from mail.kernel.org ([198.145.29.99]:56062 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1728596AbgERSHU (ORCPT ); Mon, 18 May 2020 14:07:20 -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 395A7207D3; Mon, 18 May 2020 18:07:19 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1589825239; bh=dauGskwhFdS0FQcA5fjSQecXpT+n6+sjzPuDZ4Qa8pM=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=ltSYRFDstALzko+ZVCXpQeq+wogfmc3Zem6/9tGsgcXxa2p0BKSuO3U/I36yZ6es/ 4lQ5kQkvwdUpkqYL+rLdLT6uY5Dx8Xmyu75oHih5NPLk7dpvAE/QugxuUr1DIreGcQ C0t31WkvmVVcCwhR5I6tXY/yPFl2ow8YB93rlaRs= From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, Nicholas Piggin , Michael Ellerman Subject: [PATCH 5.6 185/194] powerpc/uaccess: Evaluate macro arguments once, before user access is allowed Date: Mon, 18 May 2020 19:37:55 +0200 Message-Id: <20200518173546.870174069@linuxfoundation.org> X-Mailer: git-send-email 2.26.2 In-Reply-To: <20200518173531.455604187@linuxfoundation.org> References: <20200518173531.455604187@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: Nicholas Piggin commit d02f6b7dab8228487268298ea1f21081c0b4b3eb upstream. get/put_user() can be called with nontrivial arguments. fs/proc/page.c has a good example: if (put_user(stable_page_flags(ppage), out)) { stable_page_flags() is quite a lot of code, including spin locks in the page allocator. Ensure these arguments are evaluated before user access is allowed. This improves security by reducing code with access to userspace, but it also fixes a PREEMPT bug with KUAP on powerpc/64s: stable_page_flags() is currently called with AMR set to allow writes, it ends up calling spin_unlock(), which can call preempt_schedule. But the task switch code can not be called with AMR set (it relies on interrupts saving the register), so this blows up. It's fine if the code inside allow_user_access() is preemptible, because a timer or IPI will save the AMR, but it's not okay to explicitly cause a reschedule. Fixes: de78a9c42a79 ("powerpc: Add a framework for Kernel Userspace Access Protection") Signed-off-by: Nicholas Piggin Signed-off-by: Michael Ellerman Link: https://lore.kernel.org/r/20200407041245.600651-1-npiggin@gmail.com Signed-off-by: Greg Kroah-Hartman --- arch/powerpc/include/asm/uaccess.h | 49 ++++++++++++++++++++++++++----------- 1 file changed, 35 insertions(+), 14 deletions(-) --- a/arch/powerpc/include/asm/uaccess.h +++ b/arch/powerpc/include/asm/uaccess.h @@ -166,13 +166,17 @@ do { \ ({ \ long __pu_err; \ __typeof__(*(ptr)) __user *__pu_addr = (ptr); \ + __typeof__(*(ptr)) __pu_val = (x); \ + __typeof__(size) __pu_size = (size); \ + \ if (!is_kernel_addr((unsigned long)__pu_addr)) \ might_fault(); \ - __chk_user_ptr(ptr); \ + __chk_user_ptr(__pu_addr); \ if (do_allow) \ - __put_user_size((x), __pu_addr, (size), __pu_err); \ + __put_user_size(__pu_val, __pu_addr, __pu_size, __pu_err); \ else \ - __put_user_size_allowed((x), __pu_addr, (size), __pu_err); \ + __put_user_size_allowed(__pu_val, __pu_addr, __pu_size, __pu_err); \ + \ __pu_err; \ }) @@ -180,9 +184,13 @@ do { \ ({ \ long __pu_err = -EFAULT; \ __typeof__(*(ptr)) __user *__pu_addr = (ptr); \ + __typeof__(*(ptr)) __pu_val = (x); \ + __typeof__(size) __pu_size = (size); \ + \ might_fault(); \ - if (access_ok(__pu_addr, size)) \ - __put_user_size((x), __pu_addr, (size), __pu_err); \ + if (access_ok(__pu_addr, __pu_size)) \ + __put_user_size(__pu_val, __pu_addr, __pu_size, __pu_err); \ + \ __pu_err; \ }) @@ -190,8 +198,12 @@ do { \ ({ \ long __pu_err; \ __typeof__(*(ptr)) __user *__pu_addr = (ptr); \ - __chk_user_ptr(ptr); \ - __put_user_size((x), __pu_addr, (size), __pu_err); \ + __typeof__(*(ptr)) __pu_val = (x); \ + __typeof__(size) __pu_size = (size); \ + \ + __chk_user_ptr(__pu_addr); \ + __put_user_size(__pu_val, __pu_addr, __pu_size, __pu_err); \ + \ __pu_err; \ }) @@ -283,15 +295,18 @@ do { \ long __gu_err; \ __long_type(*(ptr)) __gu_val; \ __typeof__(*(ptr)) __user *__gu_addr = (ptr); \ - __chk_user_ptr(ptr); \ + __typeof__(size) __gu_size = (size); \ + \ + __chk_user_ptr(__gu_addr); \ if (!is_kernel_addr((unsigned long)__gu_addr)) \ might_fault(); \ barrier_nospec(); \ if (do_allow) \ - __get_user_size(__gu_val, __gu_addr, (size), __gu_err); \ + __get_user_size(__gu_val, __gu_addr, __gu_size, __gu_err); \ else \ - __get_user_size_allowed(__gu_val, __gu_addr, (size), __gu_err); \ + __get_user_size_allowed(__gu_val, __gu_addr, __gu_size, __gu_err); \ (x) = (__typeof__(*(ptr)))__gu_val; \ + \ __gu_err; \ }) @@ -300,12 +315,15 @@ do { \ long __gu_err = -EFAULT; \ __long_type(*(ptr)) __gu_val = 0; \ __typeof__(*(ptr)) __user *__gu_addr = (ptr); \ + __typeof__(size) __gu_size = (size); \ + \ might_fault(); \ - if (access_ok(__gu_addr, (size))) { \ + if (access_ok(__gu_addr, __gu_size)) { \ barrier_nospec(); \ - __get_user_size(__gu_val, __gu_addr, (size), __gu_err); \ + __get_user_size(__gu_val, __gu_addr, __gu_size, __gu_err); \ } \ (x) = (__force __typeof__(*(ptr)))__gu_val; \ + \ __gu_err; \ }) @@ -314,10 +332,13 @@ do { \ long __gu_err; \ __long_type(*(ptr)) __gu_val; \ __typeof__(*(ptr)) __user *__gu_addr = (ptr); \ - __chk_user_ptr(ptr); \ + __typeof__(size) __gu_size = (size); \ + \ + __chk_user_ptr(__gu_addr); \ barrier_nospec(); \ - __get_user_size(__gu_val, __gu_addr, (size), __gu_err); \ + __get_user_size(__gu_val, __gu_addr, __gu_size, __gu_err); \ (x) = (__force __typeof__(*(ptr)))__gu_val; \ + \ __gu_err; \ })