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=DKIMWL_WL_HIGH,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,INCLUDES_PATCH,MAILING_LIST_MULTI, MENTIONS_GIT_HOSTING,SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS,USER_AGENT_GIT 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 77687C3B1A6 for ; Fri, 14 Feb 2020 17:18:53 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 4750F222C2 for ; Fri, 14 Feb 2020 17:18:53 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1581700733; bh=zeO2gN9HmtarUY0K21o0oXGxEFJGkTaJbEhO3lDmMKU=; h=From:To:Cc:Subject:Date:In-Reply-To:References:List-ID:From; b=aqynKBnLvC/XW/GqLYUUwQssZ+DUmF97XWLLSHrC+Zk9fysrSkNuD8g60z1pUkWhe 7tVqvU1txE6LWCjk4NDdFTLIUjYDhQQTgCCq3+4vPe5mT0bImDLoB5hz49ZptYg4ZE jALiuQDh7fQhrpLkk/ItmtmdS5hjmNssteBBacDk= Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S2391255AbgBNQK5 (ORCPT ); Fri, 14 Feb 2020 11:10:57 -0500 Received: from mail.kernel.org ([198.145.29.99]:35550 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S2390030AbgBNQKK (ORCPT ); Fri, 14 Feb 2020 11:10:10 -0500 Received: from sasha-vm.mshome.net (c-73-47-72-35.hsd1.nh.comcast.net [73.47.72.35]) (using TLSv1.2 with cipher ECDHE-RSA-AES128-GCM-SHA256 (128/128 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPSA id 3B7E724691; Fri, 14 Feb 2020 16:10:09 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1581696609; bh=zeO2gN9HmtarUY0K21o0oXGxEFJGkTaJbEhO3lDmMKU=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=fpgpeVwVRzjaAwQME6ivWBFRnE+uh3SHkr5feeX5/EMvQD+wGjQYfLWX0F4idmAzl q5ZSsnWBlU7s0IkooRMM5IJroVOwbptzITg0fLun+OpqbHRSCORO28x6+h1xk6G1Ke I7udZM17AeAj9gjmM2+oKIYl1DTNTcYg4zh68GQ4= From: Sasha Levin To: linux-kernel@vger.kernel.org, stable@vger.kernel.org Cc: "Gustavo A. R. Silva" , Greg Kroah-Hartman , Sasha Levin Subject: [PATCH AUTOSEL 5.4 393/459] char: hpet: Use flexible-array member Date: Fri, 14 Feb 2020 11:00:43 -0500 Message-Id: <20200214160149.11681-393-sashal@kernel.org> X-Mailer: git-send-email 2.20.1 In-Reply-To: <20200214160149.11681-1-sashal@kernel.org> References: <20200214160149.11681-1-sashal@kernel.org> MIME-Version: 1.0 X-stable: review X-Patchwork-Hint: Ignore Content-Transfer-Encoding: 8bit Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org From: "Gustavo A. R. Silva" [ Upstream commit 987f028b8637cfa7658aa456ae73f8f21a7a7f6f ] Old code in the kernel uses 1-byte and 0-byte arrays to indicate the presence of a "variable length array": 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); There is also 0-byte arrays. Both cases pose confusion for things like sizeof(), CONFIG_FORTIFY_SOURCE, etc.[1] Instead, the preferred mechanism to declare variable-length types such as the one above is a flexible array member[2] which need to be the last member of a structure and empty-sized: struct something { int stuff; u8 data[]; }; Also, 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 unadvertenly introduced[3] to the codebase from now on. [1] https://github.com/KSPP/linux/issues/21 [2] https://gcc.gnu.org/onlinedocs/gcc/Zero-Length.html [3] commit 76497732932f ("cxgb3/l2t: Fix undefined behaviour") Signed-off-by: Gustavo A. R. Silva Link: https://lore.kernel.org/r/20200120235326.GA29231@embeddedor.com Signed-off-by: Greg Kroah-Hartman Signed-off-by: Sasha Levin --- drivers/char/hpet.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/drivers/char/hpet.c b/drivers/char/hpet.c index 9ac6671bb5141..aed2c45f7968c 100644 --- a/drivers/char/hpet.c +++ b/drivers/char/hpet.c @@ -110,7 +110,7 @@ struct hpets { unsigned long hp_delta; unsigned int hp_ntimer; unsigned int hp_which; - struct hpet_dev hp_dev[1]; + struct hpet_dev hp_dev[]; }; static struct hpets *hpets; -- 2.20.1