From patchwork Tue Jun 2 21:39:58 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: 11584569 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 0D52890 for ; Tue, 2 Jun 2020 21:34:56 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id E0D9320734 for ; Tue, 2 Jun 2020 21:34:55 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1591133695; bh=U5VQLBA0K584HyMnp25pHX350Ep4BaZZoHpAMfzXWOE=; h=Date:From:To:Cc:Subject:List-ID:From; b=nNxvjM9SMo5VzvX9rqMkj9N7/LemltVoHouyzOcUtyJ4eeRUfX6UsgPWebnvVtCz0 Zz2LhhRAXpYfIITH1xrTjMmkhf/F0lVOKEFLrG8S59gDRLG8CAFF0ZB9uhO8fxAUby qG3y3Tdwv1Gn7CloDXPltw6nBkcevmH8x0sziKzo= Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726373AbgFBVez (ORCPT ); Tue, 2 Jun 2020 17:34:55 -0400 Received: from mail.kernel.org ([198.145.29.99]:49740 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726130AbgFBVez (ORCPT ); Tue, 2 Jun 2020 17:34:55 -0400 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 F30AE206E2; Tue, 2 Jun 2020 21:34:53 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1591133694; bh=U5VQLBA0K584HyMnp25pHX350Ep4BaZZoHpAMfzXWOE=; h=Date:From:To:Cc:Subject:From; b=LHEuC4+DoL1LbalzPAmeFzSITJzZ7hODWN7PopM1OKU+1s8mHEmJJtHec0GBEaHoj 203o2uDa+HjRZEJ1ThVBUBux4B3RnuMMwJjI90C9OcpYK9g5Fej+OXAXSDFMG3iGp/ JDOBTjJS3zzuKz4zqk0Lsbfmp1Fi573mV5FbiVZk= Date: Tue, 2 Jun 2020 16:39:58 -0500 From: "Gustavo A. R. Silva" To: Robert Moore , Erik Kaneda , "Rafael J. Wysocki" , Len Brown Cc: linux-acpi@vger.kernel.org, devel@acpica.org, linux-kernel@vger.kernel.org, "Gustavo A. R. Silva" Subject: [PATCH v2] ACPICA: Replace one-element array with flexible-array Message-ID: <20200602213958.GA32150@embeddedor> MIME-Version: 1.0 Content-Disposition: inline User-Agent: Mutt/1.9.4 (2018-02-28) Sender: linux-acpi-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-acpi@vger.kernel.org The current codebase makes use of one-element arrays in the following form: struct something { int length; u8 data[1]; }; struct something *instance; instance = kmalloc(sizeof(*instance) + size, GFP_KERNEL); instance->length = size; memcpy(instance->data, source, size); 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. 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 --- Changes in v2: - Don't use struct_size() for now. - Update subject line and changelog text. drivers/acpi/acpica/utids.c | 2 +- include/acpi/actypes.h | 2 +- 2 files changed, 2 insertions(+), 2 deletions(-) diff --git a/drivers/acpi/acpica/utids.c b/drivers/acpi/acpica/utids.c index 3bb06935a2ad3..225f3c60203c7 100644 --- a/drivers/acpi/acpica/utids.c +++ b/drivers/acpi/acpica/utids.c @@ -263,7 +263,7 @@ acpi_ut_execute_CID(struct acpi_namespace_node *device_node, * 3) Size of the actual CID strings */ cid_list_size = sizeof(struct acpi_pnp_device_id_list) + - ((count - 1) * sizeof(struct acpi_pnp_device_id)) + + count * sizeof(struct acpi_pnp_device_id) + string_area_size; cid_list = ACPI_ALLOCATE_ZEROED(cid_list_size); diff --git a/include/acpi/actypes.h b/include/acpi/actypes.h index 4defed58ea338..c7bcda0ad366a 100644 --- a/include/acpi/actypes.h +++ b/include/acpi/actypes.h @@ -1145,7 +1145,7 @@ struct acpi_pnp_device_id { struct acpi_pnp_device_id_list { u32 count; /* Number of IDs in Ids array */ u32 list_size; /* Size of list, including ID strings */ - struct acpi_pnp_device_id ids[1]; /* ID array */ + struct acpi_pnp_device_id ids[]; /* ID array */ }; /*