From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-1.web.codeaurora.org [10.30.226.201]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 3446919AD5C; Mon, 7 Apr 2025 20:26:31 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=10.30.226.201 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1744057591; cv=none; b=cN5JAlo7WtzrjfKNzw845bRNmgQoO7gSBf3E3pmkAjfGSANDbL28gkTZKTtSLzi5AnPjjET3xuh07TN6i6Ofcgk0jD6TLGp+eDfBeHi2MAizYxkTn2WtHKe89WZMMe6VeCSGkh027WAScClhEVM85nyqUMC2+jyebdvhLkIncOU= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1744057591; c=relaxed/simple; bh=YoPV7SpCtl5sHSJ08RLrFQBxwqmrGZ0ybpXMYiKFVLM=; h=Date:From:To:Cc:Subject:Message-ID:References:MIME-Version: Content-Type:Content-Disposition:In-Reply-To; b=rF3uuI7A7X4fIQZM3xkxSdr8ce6vmig+5yqqDEmFIvzEtXhU3yg+7lDCpg4PxvT1sY8cv/SgnZ2TPts2Y1lv9r7MosXOTGMgvKeue86vnOpvQcHJME27Xis+HQ2JUV+0Ee568f22Oi3fCX776Rmh8lIx3qVXFT5J4YaKGuzglBg= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=IvXGPBqi; arc=none smtp.client-ip=10.30.226.201 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b="IvXGPBqi" Received: by smtp.kernel.org (Postfix) with ESMTPSA id E26AAC4CEDD; Mon, 7 Apr 2025 20:26:30 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1744057590; bh=YoPV7SpCtl5sHSJ08RLrFQBxwqmrGZ0ybpXMYiKFVLM=; h=Date:From:To:Cc:Subject:References:In-Reply-To:From; b=IvXGPBqis5OvaR2kty1cjFTu8Kp3W0XQfJrXB1cfygPLxd9DNHcwBOtZvSj7NQ7F6 AINYMsIqJ67bqxCjSgkW6go85XcFsO682NPbQh2WNKtDlDUMswuXcjmIsNOZPErp2e aTJU41bcRSGwr6+j5jyXHPwYD4zIeGQel9t2lICNvpmXea7sD7HFAmptzrVN3nIpgY VRDp+fvMgoOJH3LTSAzjKn3nVeCtF6uCFgoPytK3jF2bBgjp94SiHC6mRz9dPMPSqh k/SVx71bVx8uST7MYaOMmX9JRUgEggbfoiAUvNc2yqoieaNvstp76qEp99zY+s3fHY i+icVFtZSWlmw== Date: Mon, 7 Apr 2025 13:26:25 -0700 From: Kees Cook To: "Gustavo A. R. Silva" Cc: Krzysztof Kozlowski , linux-kernel@vger.kernel.org, linux-hardening@vger.kernel.org Subject: Re: [PATCH v2][next] w1: Avoid -Wflex-array-member-not-at-end warnings Message-ID: <202504071326.564A591@keescook> References: Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: On Mon, Apr 07, 2025 at 01:36:26PM -0600, Gustavo A. R. Silva wrote: > -Wflex-array-member-not-at-end was introduced in GCC-14, and we are > getting ready to enable it, globally. > > Use the `DEFINE_RAW_FLEX()` helper for on-stack definitions of > a flexible structure where the size of the flexible-array member > is known at compile-time, and refactor the rest of the code, > accordingly. > > So, with these changes, fix the following warnings: > > drivers/w1/w1_netlink.c:198:31: warning: structure containing a flexible array member is not at the end of another structure [-Wflex-array-member-not-at-end] > drivers/w1/w1_netlink.c:219:31: warning: structure containing a flexible array member is not at the end of another structure [-Wflex-array-member-not-at-end] > > Signed-off-by: Gustavo A. R. Silva > --- > Changes in v2: > - Fix memcpy() instance - use new pointer `pkg_msg`, instead of `packet`. (Kees) Thanks! You didn't want to use object assignments? Those are type checked. :) Reviewed-by: Kees Cook -Kees > > v1: > - Link: https://lore.kernel.org/linux-hardening/Z-WD2NP_1A0ratnI@kspp/ > > drivers/w1/w1_netlink.c | 42 ++++++++++++++++++++--------------------- > 1 file changed, 20 insertions(+), 22 deletions(-) > > diff --git a/drivers/w1/w1_netlink.c b/drivers/w1/w1_netlink.c > index 691978cddab7..724a008cf342 100644 > --- a/drivers/w1/w1_netlink.c > +++ b/drivers/w1/w1_netlink.c > @@ -194,16 +194,16 @@ static void w1_netlink_queue_status(struct w1_cb_block *block, > static void w1_netlink_send_error(struct cn_msg *cn, struct w1_netlink_msg *msg, > int portid, int error) > { > - struct { > - struct cn_msg cn; > - struct w1_netlink_msg msg; > - } packet; > - memcpy(&packet.cn, cn, sizeof(packet.cn)); > - memcpy(&packet.msg, msg, sizeof(packet.msg)); > - packet.cn.len = sizeof(packet.msg); > - packet.msg.len = 0; > - packet.msg.status = (u8)-error; > - cn_netlink_send(&packet.cn, portid, 0, GFP_KERNEL); > + DEFINE_RAW_FLEX(struct cn_msg, packet, data, > + sizeof(struct w1_netlink_msg)); > + struct w1_netlink_msg *pkt_msg = (struct w1_netlink_msg *)packet->data; > + > + memcpy(packet, cn, sizeof(*packet)); > + memcpy(pkt_msg, msg, sizeof(*pkt_msg)); > + packet->len = sizeof(*pkt_msg); > + pkt_msg->len = 0; > + pkt_msg->status = (u8)-error; > + cn_netlink_send(packet, portid, 0, GFP_KERNEL); > } > > /** > @@ -215,22 +215,20 @@ static void w1_netlink_send_error(struct cn_msg *cn, struct w1_netlink_msg *msg, > */ > void w1_netlink_send(struct w1_master *dev, struct w1_netlink_msg *msg) > { > - struct { > - struct cn_msg cn; > - struct w1_netlink_msg msg; > - } packet; > - memset(&packet, 0, sizeof(packet)); > + DEFINE_RAW_FLEX(struct cn_msg, packet, data, > + sizeof(struct w1_netlink_msg)); > + struct w1_netlink_msg *pkg_msg = (struct w1_netlink_msg *)packet->data; > > - packet.cn.id.idx = CN_W1_IDX; > - packet.cn.id.val = CN_W1_VAL; > + packet->id.idx = CN_W1_IDX; > + packet->id.val = CN_W1_VAL; > > - packet.cn.seq = dev->seq++; > - packet.cn.len = sizeof(*msg); > + packet->seq = dev->seq++; > + packet->len = sizeof(*msg); > > - memcpy(&packet.msg, msg, sizeof(*msg)); > - packet.msg.len = 0; > + memcpy(pkg_msg, msg, sizeof(*msg)); > + pkg_msg->len = 0; > > - cn_netlink_send(&packet.cn, 0, 0, GFP_KERNEL); > + cn_netlink_send(packet, 0, 0, GFP_KERNEL); > } > > static void w1_send_slave(struct w1_master *dev, u64 rn) > -- > 2.43.0 > -- Kees Cook