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=-15.1 required=3.0 tests=BAYES_00,DKIM_INVALID, DKIM_SIGNED,HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_CR_TRAILER,INCLUDES_PATCH, MAILING_LIST_MULTI,NICE_REPLY_A,SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED, USER_AGENT_SANE_1 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 E2A2BC433EF for ; Tue, 21 Sep 2021 00:03:21 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id BC96960F6B for ; Tue, 21 Sep 2021 00:03:21 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S233428AbhIUAEs (ORCPT ); Mon, 20 Sep 2021 20:04:48 -0400 Received: from gateway31.websitewelcome.com ([192.185.144.219]:26859 "EHLO gateway31.websitewelcome.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S233243AbhIUACr (ORCPT ); Mon, 20 Sep 2021 20:02:47 -0400 Received: from cm14.websitewelcome.com (cm14.websitewelcome.com [100.42.49.7]) by gateway31.websitewelcome.com (Postfix) with ESMTP id 222F6C4D22 for ; Mon, 20 Sep 2021 19:01:20 -0500 (CDT) Received: from gator4166.hostgator.com ([108.167.133.22]) by cmsmtp with SMTP id STDsmW2v1cEL1STDsm9vs6; Mon, 20 Sep 2021 19:01:20 -0500 X-Authority-Reason: nr=8 DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=embeddedor.com; s=default; h=Content-Transfer-Encoding:Content-Type: In-Reply-To:MIME-Version:Date:Message-ID:From:References:Cc:To:Subject:Sender :Reply-To:Content-ID:Content-Description:Resent-Date:Resent-From: Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID:List-Id:List-Help: List-Unsubscribe:List-Subscribe:List-Post:List-Owner:List-Archive; bh=czSdDpNgb0Ii/RJWWpIWH8ssgyJ0ANHKIaZ5AJ+/NWg=; b=eTNSUnUcbS4YXJdyxijuf+L6bU +3nwvc5H7uG93RrOlY4XaQr+WJ8j5NasVF1FSOVL0/lk0bOYG9UZE8acN2rotuQu6llY12vdmrkGU V/wsZwwCXSGfqjcL47Efj5u5L7QG7rSltVQBuNf465bB8o++v9MW7Ru5j/oTS343jFEKZWZOwZPoZ Pm+Cg0lzTlOKUEcweILPt8iBUx3r/LhGmgqJfKT7Ch/3zTdxNnb6PVKumenkJm9EbYGGsCCT1Rt1V eT9MOfKYpHUcAA3fr58PiS5injGTx47qqOPbDuIfN/4ufmiTmASdY8S6YpDmURQ6RNucrEwqKf29z PtygWsHw==; Received: from 187-162-31-110.static.axtel.net ([187.162.31.110]:33780 helo=[192.168.15.9]) by gator4166.hostgator.com with esmtpsa (TLS1.2) tls TLS_ECDHE_RSA_WITH_AES_128_GCM_SHA256 (Exim 4.94.2) (envelope-from ) id 1mSTDr-000Y7U-Iv; Mon, 20 Sep 2021 19:01:19 -0500 Subject: Re: [PATCH] KVM: PPC: Replace zero-length array with flexible array member To: Len Baker , Paul Mackerras , Michael Ellerman , Benjamin Herrenschmidt Cc: "Gustavo A. R. Silva" , Kees Cook , kvm-ppc@vger.kernel.org, linuxppc-dev@lists.ozlabs.org, linux-hardening@vger.kernel.org, linux-kernel@vger.kernel.org References: <20210918142138.17709-1-len.baker@gmx.com> From: "Gustavo A. R. Silva" Message-ID: Date: Mon, 20 Sep 2021 19:05:07 -0500 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:78.0) Gecko/20100101 Thunderbird/78.13.0 MIME-Version: 1.0 In-Reply-To: <20210918142138.17709-1-len.baker@gmx.com> Content-Type: text/plain; charset=utf-8 Content-Language: en-US Content-Transfer-Encoding: 7bit X-AntiAbuse: This header was added to track abuse, please include it with any abuse report X-AntiAbuse: Primary Hostname - gator4166.hostgator.com X-AntiAbuse: Original Domain - vger.kernel.org X-AntiAbuse: Originator/Caller UID/GID - [47 12] / [47 12] X-AntiAbuse: Sender Address Domain - embeddedor.com X-BWhitelist: no X-Source-IP: 187.162.31.110 X-Source-L: No X-Exim-ID: 1mSTDr-000Y7U-Iv X-Source: X-Source-Args: X-Source-Dir: X-Source-Sender: 187-162-31-110.static.axtel.net ([192.168.15.9]) [187.162.31.110]:33780 X-Source-Auth: gustavo@embeddedor.com X-Email-Count: 9 X-Source-Cap: Z3V6aWRpbmU7Z3V6aWRpbmU7Z2F0b3I0MTY2Lmhvc3RnYXRvci5jb20= X-Local-Domain: yes Precedence: bulk List-ID: X-Mailing-List: linux-hardening@vger.kernel.org On 9/18/21 09:21, Len Baker wrote: > There is a regular need in the kernel to provide a way to declare having > a dynamically sized set of trailing elements in a structure. Kernel code > should always use "flexible array members" [1] for these cases. The > older style of one-element or zero-length arrays should no longer be > used[2]. > > Also, make use of the struct_size() helper in kzalloc(). > > [1] https://en.wikipedia.org/wiki/Flexible_array_member > [2] https://www.kernel.org/doc/html/latest/process/deprecated.html#zero-length-and-one-element-arrays > > Signed-off-by: Len Baker Reviewed-by: Gustavo A. R. Silva Thanks -- Gustavo > --- > arch/powerpc/include/asm/kvm_host.h | 2 +- > arch/powerpc/kvm/book3s_64_vio.c | 3 +-- > 2 files changed, 2 insertions(+), 3 deletions(-) > > diff --git a/arch/powerpc/include/asm/kvm_host.h b/arch/powerpc/include/asm/kvm_host.h > index 080a7feb7731..3aed653373a5 100644 > --- a/arch/powerpc/include/asm/kvm_host.h > +++ b/arch/powerpc/include/asm/kvm_host.h > @@ -190,7 +190,7 @@ struct kvmppc_spapr_tce_table { > u64 size; /* window size in pages */ > struct list_head iommu_tables; > struct mutex alloc_lock; > - struct page *pages[0]; > + struct page *pages[]; > }; > > /* XICS components, defined in book3s_xics.c */ > diff --git a/arch/powerpc/kvm/book3s_64_vio.c b/arch/powerpc/kvm/book3s_64_vio.c > index 6365087f3160..d42b4b6d4a79 100644 > --- a/arch/powerpc/kvm/book3s_64_vio.c > +++ b/arch/powerpc/kvm/book3s_64_vio.c > @@ -295,8 +295,7 @@ long kvm_vm_ioctl_create_spapr_tce(struct kvm *kvm, > return ret; > > ret = -ENOMEM; > - stt = kzalloc(sizeof(*stt) + npages * sizeof(struct page *), > - GFP_KERNEL); > + stt = kzalloc(struct_size(stt, pages, npages), GFP_KERNEL); > if (!stt) > goto fail_acct; > > -- > 2.25.1 >