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=-2.8 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,SPF_PASS,URIBL_BLOCKED,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 EB290C07520 for ; Thu, 13 Sep 2018 13:45:07 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id AA4F220881 for ; Thu, 13 Sep 2018 13:45:07 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org AA4F220881 Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=linuxfoundation.org Authentication-Results: mail.kernel.org; spf=none smtp.mailfrom=linux-kernel-owner@vger.kernel.org Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1730112AbeIMSyh (ORCPT ); Thu, 13 Sep 2018 14:54:37 -0400 Received: from mail.linuxfoundation.org ([140.211.169.12]:60654 "EHLO mail.linuxfoundation.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1728239AbeIMSyg (ORCPT ); Thu, 13 Sep 2018 14:54:36 -0400 Received: from localhost (ip-213-127-77-73.ip.prioritytelecom.net [213.127.77.73]) by mail.linuxfoundation.org (Postfix) with ESMTPSA id E2BF0D19; Thu, 13 Sep 2018 13:45:03 +0000 (UTC) From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, Michael Ellerman , Sasha Levin Subject: [PATCH 4.14 053/115] powerpc/uaccess: Enable get_user(u64, *p) on 32-bit Date: Thu, 13 Sep 2018 15:31:13 +0200 Message-Id: <20180913131826.947176586@linuxfoundation.org> X-Mailer: git-send-email 2.19.0 In-Reply-To: <20180913131823.327472833@linuxfoundation.org> References: <20180913131823.327472833@linuxfoundation.org> User-Agent: quilt/0.65 X-stable: review 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 4.14-stable review patch. If anyone has any objections, please let me know. ------------------ From: Michael Ellerman [ Upstream commit f7a6947cd49b7ff4e03f1b4f7e7b223003d752ca ] Currently if you build a 32-bit powerpc kernel and use get_user() to load a u64 value it will fail to build with eg: kernel/rseq.o: In function `rseq_get_rseq_cs': kernel/rseq.c:123: undefined reference to `__get_user_bad' This is hitting the check in __get_user_size() that makes sure the size we're copying doesn't exceed the size of the destination: #define __get_user_size(x, ptr, size, retval) do { retval = 0; __chk_user_ptr(ptr); if (size > sizeof(x)) (x) = __get_user_bad(); Which doesn't immediately make sense because the size of the destination is u64, but it's not really, because __get_user_check() etc. internally create an unsigned long and copy into that: #define __get_user_check(x, ptr, size) ({ long __gu_err = -EFAULT; unsigned long __gu_val = 0; The problem being that on 32-bit unsigned long is not big enough to hold a u64. We can fix this with a trick from hpa in the x86 code, we statically check the type of x and set the type of __gu_val to either unsigned long or unsigned long long. Signed-off-by: Michael Ellerman Signed-off-by: Sasha Levin Signed-off-by: Greg Kroah-Hartman --- arch/powerpc/include/asm/uaccess.h | 13 ++++++++++--- 1 file changed, 10 insertions(+), 3 deletions(-) --- a/arch/powerpc/include/asm/uaccess.h +++ b/arch/powerpc/include/asm/uaccess.h @@ -223,10 +223,17 @@ do { \ } \ } while (0) +/* + * This is a type: either unsigned long, if the argument fits into + * that type, or otherwise unsigned long long. + */ +#define __long_type(x) \ + __typeof__(__builtin_choose_expr(sizeof(x) > sizeof(0UL), 0ULL, 0UL)) + #define __get_user_nocheck(x, ptr, size) \ ({ \ long __gu_err; \ - unsigned long __gu_val; \ + __long_type(*(ptr)) __gu_val; \ const __typeof__(*(ptr)) __user *__gu_addr = (ptr); \ __chk_user_ptr(ptr); \ if (!is_kernel_addr((unsigned long)__gu_addr)) \ @@ -239,7 +246,7 @@ do { \ #define __get_user_check(x, ptr, size) \ ({ \ long __gu_err = -EFAULT; \ - unsigned long __gu_val = 0; \ + __long_type(*(ptr)) __gu_val = 0; \ const __typeof__(*(ptr)) __user *__gu_addr = (ptr); \ might_fault(); \ if (access_ok(VERIFY_READ, __gu_addr, (size))) \ @@ -251,7 +258,7 @@ do { \ #define __get_user_nosleep(x, ptr, size) \ ({ \ long __gu_err; \ - unsigned long __gu_val; \ + __long_type(*(ptr)) __gu_val; \ const __typeof__(*(ptr)) __user *__gu_addr = (ptr); \ __chk_user_ptr(ptr); \ __get_user_size(__gu_val, __gu_addr, (size), __gu_err); \