From patchwork Thu May 7 18:51:58 2020 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: "Gustavo A. R. Silva" X-Patchwork-Id: 11539933 X-Patchwork-Delegate: snitzer@redhat.com Return-Path: Received: from mail.kernel.org (pdx-korg-mail-1.web.codeaurora.org [172.30.200.123]) by pdx-korg-patchwork-2.web.codeaurora.org (Postfix) with ESMTP id 1D0CB913 for ; Mon, 11 May 2020 08:18:43 +0000 (UTC) Received: from us-smtp-1.mimecast.com (us-smtp-delivery-1.mimecast.com [207.211.31.120]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPS id CDAF0206F5 for ; Mon, 11 May 2020 08:18:42 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (1024-bit key) header.d=redhat.com header.i=@redhat.com header.b="Of2TwKk1" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org CDAF0206F5 Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=kernel.org Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=dm-devel-bounces@redhat.com DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1589185121; h=from:from:sender:sender:reply-to:subject:subject:date:date: message-id:message-id:to:to:cc:cc:mime-version:mime-version: content-type:content-type: content-transfer-encoding:content-transfer-encoding:list-id:list-help: list-unsubscribe:list-subscribe:list-post; bh=1GzGTbT2MQZkzKewYyRQWvtYnM4bfZwVgTSOXkscbV4=; b=Of2TwKk1tyVJXqw/ez23mQXGcNqrRDQoIi72XxYTRtxKLaRnenoeje2jg0MZr+T02zQk04 m7EHS6fWYYmg4G8aGZ9iUc7AydWS0KkFbTNNH9V6IanO6uVHossX4893r92flWyPmgCzYb pPeB0JN9sKctu7aFFCn1ESpicl51H+s= Received: from mimecast-mx01.redhat.com (mimecast-mx01.redhat.com [209.132.183.4]) (Using TLS) by relay.mimecast.com with ESMTP id us-mta-83-4tbXXN4kNp-t2pMjJbXG8Q-1; Mon, 11 May 2020 04:18:38 -0400 X-MC-Unique: 4tbXXN4kNp-t2pMjJbXG8Q-1 Received: from smtp.corp.redhat.com (int-mx07.intmail.prod.int.phx2.redhat.com [10.5.11.22]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mimecast-mx01.redhat.com (Postfix) with ESMTPS id 728AE801503; Mon, 11 May 2020 08:18:33 +0000 (UTC) Received: from colo-mx.corp.redhat.com (colo-mx01.intmail.prod.int.phx2.redhat.com [10.5.11.20]) by smtp.corp.redhat.com (Postfix) with ESMTPS id 2E61910016DA; Mon, 11 May 2020 08:18:33 +0000 (UTC) Received: from lists01.pubmisc.prod.ext.phx2.redhat.com (lists01.pubmisc.prod.ext.phx2.redhat.com [10.5.19.33]) by colo-mx.corp.redhat.com (Postfix) with ESMTP id 83C17180954D; Mon, 11 May 2020 08:18:31 +0000 (UTC) Received: from smtp.corp.redhat.com (int-mx05.intmail.prod.int.rdu2.redhat.com [10.11.54.5]) by lists01.pubmisc.prod.ext.phx2.redhat.com (8.13.8/8.13.8) with ESMTP id 047IrhOh016442 for ; Thu, 7 May 2020 14:53:43 -0400 Received: by smtp.corp.redhat.com (Postfix) id 717E311231C; Thu, 7 May 2020 18:53:43 +0000 (UTC) Delivered-To: dm-devel@redhat.com Received: from mimecast-mx02.redhat.com (mimecast02.extmail.prod.ext.rdu2.redhat.com [10.11.55.18]) by smtp.corp.redhat.com (Postfix) with ESMTPS id 6DBF911515F for ; Thu, 7 May 2020 18:53:37 +0000 (UTC) Received: from us-smtp-1.mimecast.com (us-smtp-2.mimecast.com [207.211.31.81]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-SHA384 (256/256 bits)) (No client certificate requested) by mimecast-mx02.redhat.com (Postfix) with ESMTPS id D972E800C6D for ; Thu, 7 May 2020 18:53:37 +0000 (UTC) Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) (Using TLS) by relay.mimecast.com with ESMTP id us-mta-489-AfHM2bsaPuKTZ3QEEJQ_yA-1; Thu, 07 May 2020 14:53:34 -0400 X-MC-Unique: AfHM2bsaPuKTZ3QEEJQ_yA-1 Received: from embeddedor (unknown [189.207.59.248]) (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 03278216FD; Thu, 7 May 2020 18:47:31 +0000 (UTC) Date: Thu, 7 May 2020 13:51:58 -0500 From: "Gustavo A. R. Silva" To: Alasdair Kergon , Mike Snitzer , dm-devel@redhat.com Message-ID: <20200507185158.GA14116@embeddedor> MIME-Version: 1.0 User-Agent: Mutt/1.9.4 (2018-02-28) X-Mimecast-Spam-Signature: yes X-Scanned-By: MIMEDefang 2.79 on 10.11.54.5 X-MIME-Autoconverted: from quoted-printable to 8bit by lists01.pubmisc.prod.ext.phx2.redhat.com id 047IrhOh016442 X-loop: dm-devel@redhat.com X-Mailman-Approved-At: Mon, 11 May 2020 04:18:30 -0400 Cc: dm-devel@redhat.com, linux-kernel@vger.kernel.org Subject: [dm-devel] [PATCH] dm integrity: Replace zero-length array with flexible-array X-BeenThere: dm-devel@redhat.com X-Mailman-Version: 2.1.12 Precedence: junk List-Id: device-mapper development List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Sender: dm-devel-bounces@redhat.com Errors-To: dm-devel-bounces@redhat.com X-Scanned-By: MIMEDefang 2.84 on 10.5.11.22 X-Mimecast-Spam-Score: 0 X-Mimecast-Originator: redhat.com Content-Disposition: inline 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. This issue was found with the help of Coccinelle. [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 --- drivers/md/dm-crypt.c | 2 +- drivers/md/dm-integrity.c | 2 +- drivers/md/dm-log-writes.c | 2 +- drivers/md/dm-raid.c | 2 +- drivers/md/dm-raid1.c | 2 +- drivers/md/dm-stats.c | 2 +- drivers/md/dm-stripe.c | 2 +- drivers/md/dm-switch.c | 2 +- drivers/md/persistent-data/dm-btree-internal.h | 2 +- 9 files changed, 9 insertions(+), 9 deletions(-) -- dm-devel mailing list dm-devel@redhat.com https://www.redhat.com/mailman/listinfo/dm-devel diff --git a/drivers/md/dm-crypt.c b/drivers/md/dm-crypt.c index 3df90daba89e..bac110987a65 100644 --- a/drivers/md/dm-crypt.c +++ b/drivers/md/dm-crypt.c @@ -212,7 +212,7 @@ struct crypt_config { struct mutex bio_alloc_lock; u8 *authenc_key; /* space for keys in authenc() format (if used) */ - u8 key[0]; + u8 key[]; }; #define MIN_IOS 64 diff --git a/drivers/md/dm-integrity.c b/drivers/md/dm-integrity.c index 4094c47eca7f..fe39ed31b20d 100644 --- a/drivers/md/dm-integrity.c +++ b/drivers/md/dm-integrity.c @@ -92,7 +92,7 @@ struct journal_entry { } s; __u64 sector; } u; - commit_id_t last_bytes[0]; + commit_id_t last_bytes[]; /* __u8 tag[0]; */ }; diff --git a/drivers/md/dm-log-writes.c b/drivers/md/dm-log-writes.c index 8ea20b56b4d6..e3d35c6c9f71 100644 --- a/drivers/md/dm-log-writes.c +++ b/drivers/md/dm-log-writes.c @@ -127,7 +127,7 @@ struct pending_block { char *data; u32 datalen; struct list_head list; - struct bio_vec vecs[0]; + struct bio_vec vecs[]; }; struct per_bio_data { diff --git a/drivers/md/dm-raid.c b/drivers/md/dm-raid.c index 9a18bef0a5ff..10e8b2fe787b 100644 --- a/drivers/md/dm-raid.c +++ b/drivers/md/dm-raid.c @@ -254,7 +254,7 @@ struct raid_set { int mode; } journal_dev; - struct raid_dev dev[0]; + struct raid_dev dev[]; }; static void rs_config_backup(struct raid_set *rs, struct rs_layout *l) diff --git a/drivers/md/dm-raid1.c b/drivers/md/dm-raid1.c index 089aed57e083..2f655d9f4200 100644 --- a/drivers/md/dm-raid1.c +++ b/drivers/md/dm-raid1.c @@ -83,7 +83,7 @@ struct mirror_set { struct work_struct trigger_event; unsigned nr_mirrors; - struct mirror mirror[0]; + struct mirror mirror[]; }; DECLARE_DM_KCOPYD_THROTTLE_WITH_MODULE_PARM(raid1_resync_throttle, diff --git a/drivers/md/dm-stats.c b/drivers/md/dm-stats.c index 71417048256a..35d368c418d0 100644 --- a/drivers/md/dm-stats.c +++ b/drivers/md/dm-stats.c @@ -56,7 +56,7 @@ struct dm_stat { size_t percpu_alloc_size; size_t histogram_alloc_size; struct dm_stat_percpu *stat_percpu[NR_CPUS]; - struct dm_stat_shared stat_shared[0]; + struct dm_stat_shared stat_shared[]; }; #define STAT_PRECISE_TIMESTAMPS 1 diff --git a/drivers/md/dm-stripe.c b/drivers/md/dm-stripe.c index fa813c0f993d..151d022b032d 100644 --- a/drivers/md/dm-stripe.c +++ b/drivers/md/dm-stripe.c @@ -41,7 +41,7 @@ struct stripe_c { /* Work struct used for triggering events*/ struct work_struct trigger_event; - struct stripe stripe[0]; + struct stripe stripe[]; }; /* diff --git a/drivers/md/dm-switch.c b/drivers/md/dm-switch.c index 8a0f057b8122..bff4c7fa1cd2 100644 --- a/drivers/md/dm-switch.c +++ b/drivers/md/dm-switch.c @@ -53,7 +53,7 @@ struct switch_ctx { /* * Array of dm devices to switch between. */ - struct switch_path path_list[0]; + struct switch_path path_list[]; }; static struct switch_ctx *alloc_switch_ctx(struct dm_target *ti, unsigned nr_paths, diff --git a/drivers/md/persistent-data/dm-btree-internal.h b/drivers/md/persistent-data/dm-btree-internal.h index a240990a7f33..f4e644dd8101 100644 --- a/drivers/md/persistent-data/dm-btree-internal.h +++ b/drivers/md/persistent-data/dm-btree-internal.h @@ -38,7 +38,7 @@ struct node_header { struct btree_node { struct node_header header; - __le64 keys[0]; + __le64 keys[]; } __packed;