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=-11.7 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_PATCH,MAILING_LIST_MULTI, MENTIONS_GIT_HOSTING,SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED 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 C6794C433E0 for ; Fri, 19 Jun 2020 16:46:44 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id A66342166E for ; Fri, 19 Jun 2020 16:46:44 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S2405676AbgFSQqj (ORCPT ); Fri, 19 Jun 2020 12:46:39 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:43804 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S2395254AbgFSQqI (ORCPT ); Fri, 19 Jun 2020 12:46:08 -0400 Received: from Galois.linutronix.de (Galois.linutronix.de [IPv6:2a0a:51c0:0:12e:550::1]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 68BE5C061797; Fri, 19 Jun 2020 09:46:03 -0700 (PDT) Received: from [5.158.153.53] (helo=tip-bot2.lab.linutronix.de) by Galois.linutronix.de with esmtpsa (TLS1.2:DHE_RSA_AES_256_CBC_SHA256:256) (Exim 4.80) (envelope-from ) id 1jmK9Q-00044S-QK; Fri, 19 Jun 2020 18:46:00 +0200 Received: from [127.0.1.1] (localhost [IPv6:::1]) by tip-bot2.lab.linutronix.de (Postfix) with ESMTP id 621211C0085; Fri, 19 Jun 2020 18:46:00 +0200 (CEST) Date: Fri, 19 Jun 2020 16:46:00 -0000 From: "tip-bot2 for Gustavo A. R. Silva" Reply-to: linux-kernel@vger.kernel.org To: linux-tip-commits@vger.kernel.org Subject: [tip: efi/urgent] efi: Replace zero-length array and use struct_size() helper Cc: "Gustavo A. R. Silva" , Kees Cook , Ard Biesheuvel , x86 , LKML In-Reply-To: <20200527171425.GA4053@embeddedor> References: <20200527171425.GA4053@embeddedor> MIME-Version: 1.0 Message-ID: <159258516013.16989.1720287565955551679.tip-bot2@tip-bot2> X-Mailer: tip-git-log-daemon Robot-ID: Robot-Unsubscribe: Contact to get blacklisted from these emails Content-Type: text/plain; charset="utf-8" Content-Transfer-Encoding: 7bit X-Linutronix-Spam-Score: -1.0 X-Linutronix-Spam-Level: - X-Linutronix-Spam-Status: No , -1.0 points, 5.0 required, ALL_TRUSTED=-1,SHORTCIRCUIT=-0.0001 Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org The following commit has been merged into the efi/urgent branch of tip: Commit-ID: 2963795122f50b36ed16e3ba880c3ed2de1bda6e Gitweb: https://git.kernel.org/tip/2963795122f50b36ed16e3ba880c3ed2de1bda6e Author: Gustavo A. R. Silva AuthorDate: Wed, 27 May 2020 12:14:25 -05:00 Committer: Ard Biesheuvel CommitterDate: Mon, 15 Jun 2020 14:38:56 +02:00 efi: Replace zero-length array and use struct_size() helper The current codebase makes use of the zero-length array language extension to the C90 standard, but the preferred mechanism to declare variable-length types such as these ones is a flexible array member[1][2], introduced in C99: struct foo { int stuff; struct boo array[]; }; By making use of the mechanism above, we will get a compiler warning in case the flexible array does not occur last in the structure, which will help us prevent some kind of undefined behavior bugs from being inadvertently introduced[3] to the codebase from now on. Also, notice that, dynamic memory allocations won't be affected by this change: "Flexible array members have incomplete type, and so the sizeof operator may not be applied. As a quirk of the original implementation of zero-length arrays, sizeof evaluates to zero."[1] sizeof(flexible-array-member) triggers a warning because flexible array members have incomplete type[1]. There are some instances of code in which the sizeof operator is being incorrectly/erroneously applied to zero-length arrays and the result is zero. Such instances may be hiding some bugs. So, this work (flexible-array member conversions) will also help to get completely rid of those sorts of issues. Lastly, make use of the sizeof_field() helper instead of an open-coded version. This issue was found with the help of Coccinelle and audited _manually_. [1] https://gcc.gnu.org/onlinedocs/gcc/Zero-Length.html [2] https://github.com/KSPP/linux/issues/21 [3] commit 76497732932f ("cxgb3/l2t: Fix undefined behaviour") Signed-off-by: Gustavo A. R. Silva Reviewed-by: Kees Cook Link: https://lore.kernel.org/r/20200527171425.GA4053@embeddedor Signed-off-by: Ard Biesheuvel --- drivers/firmware/efi/efi.c | 3 ++- include/linux/efi.h | 7 ++----- 2 files changed, 4 insertions(+), 6 deletions(-) diff --git a/drivers/firmware/efi/efi.c b/drivers/firmware/efi/efi.c index 7f1657b..edc5d36 100644 --- a/drivers/firmware/efi/efi.c +++ b/drivers/firmware/efi/efi.c @@ -622,7 +622,8 @@ int __init efi_config_parse_tables(const efi_config_table_t *config_tables, rsv = (void *)(p + prsv % PAGE_SIZE); /* reserve the entry itself */ - memblock_reserve(prsv, EFI_MEMRESERVE_SIZE(rsv->size)); + memblock_reserve(prsv, + struct_size(rsv, entry, rsv->size)); for (i = 0; i < atomic_read(&rsv->count); i++) { memblock_reserve(rsv->entry[i].base, diff --git a/include/linux/efi.h b/include/linux/efi.h index 2c6495f..c3449c9 100644 --- a/include/linux/efi.h +++ b/include/linux/efi.h @@ -1236,14 +1236,11 @@ struct linux_efi_memreserve { struct { phys_addr_t base; phys_addr_t size; - } entry[0]; + } entry[]; }; -#define EFI_MEMRESERVE_SIZE(count) (sizeof(struct linux_efi_memreserve) + \ - (count) * sizeof(((struct linux_efi_memreserve *)0)->entry[0])) - #define EFI_MEMRESERVE_COUNT(size) (((size) - sizeof(struct linux_efi_memreserve)) \ - / sizeof(((struct linux_efi_memreserve *)0)->entry[0])) + / sizeof_field(struct linux_efi_memreserve, entry[0])) void __init efi_arch_mem_reserve(phys_addr_t addr, u64 size);