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=-15.5 required=3.0 tests=BAYES_00, 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=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 8D66FC4338F for ; Wed, 28 Jul 2021 21:46:02 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 7008460F02 for ; Wed, 28 Jul 2021 21:46:02 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S231892AbhG1VqC (ORCPT ); Wed, 28 Jul 2021 17:46:02 -0400 Received: from mail-pj1-f49.google.com ([209.85.216.49]:40676 "EHLO mail-pj1-f49.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S230156AbhG1VqA (ORCPT ); Wed, 28 Jul 2021 17:46:00 -0400 Received: by mail-pj1-f49.google.com with SMTP id u9-20020a17090a1f09b029017554809f35so12204025pja.5; Wed, 28 Jul 2021 14:45:58 -0700 (PDT) X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:subject:to:cc:references:from:message-id:date :user-agent:mime-version:in-reply-to:content-language :content-transfer-encoding; bh=XicekCZGMuTmx7BgzDuVSPZdtJx2YNBwg9Vgy0Mbawo=; b=VsdJVD9iLYkTZckyM9peEdy+mj36F+LurPNiPrqbBO6rJKeUSWwHC90l6NckKkKhfo zAy4Mz7RazjHVctU+QhA1AFPT+vWsk+WdTqR7QOCBeSQoHgVn+A/Z83IxjJr6j4hZXJs 0uerb8kXtF31NZkzAthE0gRaNV/BtrgQP0a589Xgj/oDHp4zPIQ1qp++TltPKeXqXwSJ LC3BLPoTYx2M7VjImbGndHv2Tg79A0ywsKJE+PswfiIzKTRekyvR2uqAXbfSJ7LM+6qh BdoqCYnLtO0vHhagqQedYZZt9KUcvywgBvk4gcJilvXFFwJRSowpP1T+oCYwNcLqQ6af xo6w== X-Gm-Message-State: AOAM531C83eFuhpmkEosL4s1i1/EdD6jkGzrdl4onTfDWVAkaLu8VbqH aiVm+XQTeQ5ZQnl90gUcZSU= X-Google-Smtp-Source: ABdhPJw8GLTntP9/607bFZm4hvTLuV2RygVm16ypIjamKfpthJMPHWWs51SpMIWNplCV818V7piMmg== X-Received: by 2002:a62:61c3:0:b029:35b:cb61:d2c3 with SMTP id v186-20020a6261c30000b029035bcb61d2c3mr1780844pfb.62.1627508758153; Wed, 28 Jul 2021 14:45:58 -0700 (PDT) Received: from bvanassche-linux.mtv.corp.google.com ([2620:15c:211:1:3328:5f8d:f6e2:85ea]) by smtp.gmail.com with ESMTPSA id b15sm876167pgj.60.2021.07.28.14.45.56 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Wed, 28 Jul 2021 14:45:57 -0700 (PDT) Subject: Re: [PATCH 48/64] drbd: Use struct_group() to zero algs To: Kees Cook , linux-hardening@vger.kernel.org Cc: "Gustavo A. R. Silva" , Keith Packard , Greg Kroah-Hartman , Andrew Morton , linux-kernel@vger.kernel.org, linux-wireless@vger.kernel.org, netdev@vger.kernel.org, dri-devel@lists.freedesktop.org, linux-staging@lists.linux.dev, linux-block@vger.kernel.org, linux-kbuild@vger.kernel.org, clang-built-linux@googlegroups.com References: <20210727205855.411487-1-keescook@chromium.org> <20210727205855.411487-49-keescook@chromium.org> From: Bart Van Assche Message-ID: <1cc74e5e-8d28-6da4-244e-861eac075ca2@acm.org> Date: Wed, 28 Jul 2021 14:45:55 -0700 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:78.0) Gecko/20100101 Thunderbird/78.12.0 MIME-Version: 1.0 In-Reply-To: <20210727205855.411487-49-keescook@chromium.org> Content-Type: text/plain; charset=utf-8; format=flowed Content-Language: en-US Content-Transfer-Encoding: 7bit Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 7/27/21 1:58 PM, Kees Cook wrote: > In preparation for FORTIFY_SOURCE performing compile-time and run-time > field bounds checking for memset(), avoid intentionally writing across > neighboring fields. > > Add a struct_group() for the algs so that memset() can correctly reason > about the size. > > Signed-off-by: Kees Cook > --- > drivers/block/drbd/drbd_main.c | 3 ++- > drivers/block/drbd/drbd_protocol.h | 6 ++++-- > drivers/block/drbd/drbd_receiver.c | 3 ++- > 3 files changed, 8 insertions(+), 4 deletions(-) > > diff --git a/drivers/block/drbd/drbd_main.c b/drivers/block/drbd/drbd_main.c > index 55234a558e98..b824679cfcb2 100644 > --- a/drivers/block/drbd/drbd_main.c > +++ b/drivers/block/drbd/drbd_main.c > @@ -729,7 +729,8 @@ int drbd_send_sync_param(struct drbd_peer_device *peer_device) > cmd = apv >= 89 ? P_SYNC_PARAM89 : P_SYNC_PARAM; > > /* initialize verify_alg and csums_alg */ > - memset(p->verify_alg, 0, 2 * SHARED_SECRET_MAX); > + BUILD_BUG_ON(sizeof(p->algs) != 2 * SHARED_SECRET_MAX); > + memset(&p->algs, 0, sizeof(p->algs)); > > if (get_ldev(peer_device->device)) { > dc = rcu_dereference(peer_device->device->ldev->disk_conf); > diff --git a/drivers/block/drbd/drbd_protocol.h b/drivers/block/drbd/drbd_protocol.h > index dea59c92ecc1..a882b65ab5d2 100644 > --- a/drivers/block/drbd/drbd_protocol.h > +++ b/drivers/block/drbd/drbd_protocol.h > @@ -283,8 +283,10 @@ struct p_rs_param_89 { > > struct p_rs_param_95 { > u32 resync_rate; > - char verify_alg[SHARED_SECRET_MAX]; > - char csums_alg[SHARED_SECRET_MAX]; > + struct_group(algs, > + char verify_alg[SHARED_SECRET_MAX]; > + char csums_alg[SHARED_SECRET_MAX]; > + ); > u32 c_plan_ahead; > u32 c_delay_target; > u32 c_fill_target; > diff --git a/drivers/block/drbd/drbd_receiver.c b/drivers/block/drbd/drbd_receiver.c > index 1f740e42e457..6df2539e215b 100644 > --- a/drivers/block/drbd/drbd_receiver.c > +++ b/drivers/block/drbd/drbd_receiver.c > @@ -3921,7 +3921,8 @@ static int receive_SyncParam(struct drbd_connection *connection, struct packet_i > > /* initialize verify_alg and csums_alg */ > p = pi->data; > - memset(p->verify_alg, 0, 2 * SHARED_SECRET_MAX); > + BUILD_BUG_ON(sizeof(p->algs) != 2 * SHARED_SECRET_MAX); > + memset(&p->algs, 0, sizeof(p->algs)); Using struct_group() introduces complexity. Has it been considered not to modify struct p_rs_param_95 and instead to use two memset() calls instead of one (one memset() call per member)? Thanks, Bart.