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 Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 139FAC83F2C for ; Tue, 5 Sep 2023 16:23:43 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S242687AbjIEQXo (ORCPT ); Tue, 5 Sep 2023 12:23:44 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:41558 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1344800AbjIEDzh (ORCPT ); Mon, 4 Sep 2023 23:55:37 -0400 Received: from dfw.source.kernel.org (dfw.source.kernel.org [IPv6:2604:1380:4641:c500::1]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id CC85718C for ; Mon, 4 Sep 2023 20:55:33 -0700 (PDT) Received: from smtp.kernel.org (relay.kernel.org [52.25.139.140]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature RSA-PSS (2048 bits)) (No client certificate requested) by dfw.source.kernel.org (Postfix) with ESMTPS id 4878461055 for ; Tue, 5 Sep 2023 03:55:33 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id 69398C433C8; Tue, 5 Sep 2023 03:55:32 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1693886132; bh=lLVUEbQlWPdqOrLlxxs6XsBseI0buyWLU4uLdO6rjow=; h=Date:From:To:CC:Subject:In-Reply-To:References:From; b=LDgmblXsH4okbJodYbvPlniFpqN89lQ3SXmqVe4Sou8FN9xKjLrSFjBDGFuoSKyI6 IOEaFE6uB3BhB3gwDFcvOp2WwwJYxrwWvCHIdNjvOx7zBWzGPyYtV4INNUW38Ows7m gdTtPqDbO6Sb0BX1eZ3TXqki38Amve8jq4HFpqlV/UTCPVXncFTYPZ20TDabvSqpsF 48tGKtjsEjME/ZI+OxkaSBZIcyOqutkOyg6WqtgrOWemq2jkQ24TMbAG8oauYDMGig E5TSxZlBEuHqoJvBReR0SjCNZCPvLClNBKhGR3+lZdFSteZT9RYnle6kdk+uV05pDL 2Ro3z09UFvMFw== Date: Mon, 04 Sep 2023 20:55:29 -0700 From: Kees Cook To: Przemek Kitszel , netdev@vger.kernel.org CC: Kees Cook , Jacob Keller , intel-wired-lan@lists.osuosl.org, Alexander Lobakin , linux-hardening@vger.kernel.org, Steven Zou , Jakub Kicinski , Anthony Nguyen , David Laight Subject: =?US-ASCII?Q?Re=3A_=5BRFC_net-next_v4_1/7=5D_overflow=3A_?= =?US-ASCII?Q?add_DEFINE=5FFLEX=28=29_for_on-stack_allocs?= User-Agent: K-9 Mail for Android In-Reply-To: <20230904123107.116381-2-przemyslaw.kitszel@intel.com> References: <20230904123107.116381-1-przemyslaw.kitszel@intel.com> <20230904123107.116381-2-przemyslaw.kitszel@intel.com> Message-ID: <7AB970A3-883F-49A4-BBCD-23E2CD1E869C@kernel.org> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: quoted-printable Precedence: bulk List-ID: X-Mailing-List: linux-hardening@vger.kernel.org On September 4, 2023 5:31:01 AM PDT, Przemek Kitszel wrote: > [=2E=2E=2E] >+/** >+ * _DEFINE_FLEX() - helper macro for DEFINE_FLEX() family=2E >+ * Enables caller macro to pass (different) initializer=2E >+ * >+ * @type: structure type name, including "struct" keyword=2E >+ * @name: Name for a variable to define=2E >+ * @member: Name of the array member=2E >+ * @count: Number of elements in the array; must be compile-time const= =2E >+ * @initializer: initializer expression (could be empty for no init)=2E >+ */ >+#define _DEFINE_FLEX(type, name, member, count, initializer) \ >+ _Static_assert(__builtin_constant_p(count), \ >+ "onstack flex array members require compile-time const count");= \ >+ union { \ >+ u8 bytes[struct_size_t(type, member, count)]; \ >+ type obj; \ >+ } name##_u initializer; \ >+ type *name =3D (type *)&name##_u Yeah, I like this! This will make it easy to add __counted_by initializers= when we have the need in the future=2E --=20 Kees Cook