From nobody Tue Dec 2 01:22:05 2025 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 D40FA284689; Tue, 25 Nov 2025 04:27:44 +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=1764044864; cv=none; b=meQS2+8YM13me+BNHDVmHJWVM3CvCtaVyRBmg8Y3jow4vSuUmFRRSB63cdHw2sy8gtLcji145ZaWROzieCop6Ekj5sgJLOGO0SSO+boPYbu+vksD/1hnCYRLuBdDKWa/CzvaWDfwNKIY4oXNNjPWQtdQUUyb5Xmod20dYcKYtJQ= ARC-Message-Signature: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1764044864; c=relaxed/simple; bh=dJz1VBLyE+1afRYMUHSehOjVIEK7YWP+3LTbyiNgxhg=; h=Date:From:To:Cc:Subject:Message-ID:MIME-Version:Content-Type: Content-Disposition; b=laQjqbiKj8ZWmAQAvOcYqxuizMMgp0TV64zD9sZisCif5cAYMyzkvNkaAuVkFEA8h//CNs45WfPvqnYm4t1VSm6TvdtDjjGVEpQa3kdEbhk1IBBSjZQsvnn7vKFkiRMr3Mg/hgQTVIxaK2dTFN/+pA+hqFfA+VlWXj//2EWbZr8= ARC-Authentication-Results: i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=cHd5+0qB; 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="cHd5+0qB" Received: by smtp.kernel.org (Postfix) with ESMTPSA id CCB5FC4CEF1; Tue, 25 Nov 2025 04:27:41 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1764044864; bh=dJz1VBLyE+1afRYMUHSehOjVIEK7YWP+3LTbyiNgxhg=; h=Date:From:To:Cc:Subject:From; b=cHd5+0qBYv/8Dk5RSM9tgM/Q0SGPiQH0vm5nrh7oxoBKXd0PvzVC1CJCWfPJlXZjm oGxykI1RMQp9E4C36lE5c9k5+37gZfKCifBSxC0TbIflhXqRtSe+tLm7XGOhCFD553 z0CepCnKXi4+KbfJPIvb/Pqu9zxPmJBp5Db5mn+cEeq223i2tSZvGVE7rnez1aKjJt 5iK2kCKniIvJh3ds1/aZme/+QkHfkA+lYm3XNIhgWrmJ/lxN/r2+lOAIvpDd9iuA0K cE+Vu3cvYxrVahhxEO9zB+ly+FKlS75bypjsGDqQ8Nsrk2wcBuWFwFjfL5MAuYN/+X NyPEGQR7629cA== Date: Tue, 25 Nov 2025 13:27:38 +0900 From: "Gustavo A. R. Silva" To: Loic Poulain , Sergey Ryazanov , Johannes Berg , Andrew Lunn , "David S. Miller" , Eric Dumazet , Jakub Kicinski , Paolo Abeni Cc: netdev@vger.kernel.org, linux-kernel@vger.kernel.org, "Gustavo A. R. Silva" , linux-hardening@vger.kernel.org Subject: [PATCH v2][next] net: wwan: mhi_wwan_mbim: Avoid -Wflex-array-member-not-at-end warning Message-ID: Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Disposition: inline Content-Transfer-Encoding: quoted-printable Content-Type: text/plain; charset="utf-8" Use DEFINE_RAW_FLEX() to avoid a -Wflex-array-member-not-at-end warning. Remove fixed-size array struct usb_cdc_ncm_dpe16 dpe16[2]; from struct mbim_tx_hdr, so that flex-array member struct mbim_tx_hdr::ndp16.dpe16[] ends last in this structure. Compensate for this by using the DEFINE_RAW_FLEX() helper to declare the on-stack struct instance that contains struct usb_cdc_ncm_ndp16 as a member. Adjust the rest of the code, accordingly. So, with these changes fix the following warning: drivers/net/wwan/mhi_wwan_mbim.c:81:34: warning: structure containing a fle= xible array member is not at the end of another structure [-Wflex-array-mem= ber-not-at-end] Signed-off-by: Gustavo A. R. Silva Reviewed-by: Loic Poulain --- Changes in v2: - Add code comment to prevent people from adding new members after flex struct member `struct usb_cdc_ncm_ndp16 ndp16;` v1: - Link: https://lore.kernel.org/linux-hardening/aSUubvYfGJ-BIeDq@kspp/ drivers/net/wwan/mhi_wwan_mbim.c | 16 ++++++++-------- 1 file changed, 8 insertions(+), 8 deletions(-) diff --git a/drivers/net/wwan/mhi_wwan_mbim.c b/drivers/net/wwan/mhi_wwan_m= bim.c index c814fbd756a1..313dc5207c93 100644 --- a/drivers/net/wwan/mhi_wwan_mbim.c +++ b/drivers/net/wwan/mhi_wwan_mbim.c @@ -78,8 +78,9 @@ struct mhi_mbim_context { =20 struct mbim_tx_hdr { struct usb_cdc_ncm_nth16 nth16; + + /* Must be last as it ends in a flexible-array member. */ struct usb_cdc_ncm_ndp16 ndp16; - struct usb_cdc_ncm_dpe16 dpe16[2]; } __packed; =20 static struct mhi_mbim_link *mhi_mbim_get_link_rcu(struct mhi_mbim_context= *mbim, @@ -107,20 +108,20 @@ static int mhi_mbim_get_link_mux_id(struct mhi_contro= ller *cntrl) static struct sk_buff *mbim_tx_fixup(struct sk_buff *skb, unsigned int ses= sion, u16 tx_seq) { + DEFINE_RAW_FLEX(struct mbim_tx_hdr, mbim_hdr, ndp16.dpe16, 2); unsigned int dgram_size =3D skb->len; struct usb_cdc_ncm_nth16 *nth16; struct usb_cdc_ncm_ndp16 *ndp16; - struct mbim_tx_hdr *mbim_hdr; =20 /* Only one NDP is sent, containing the IP packet (no aggregation) */ =20 /* Ensure we have enough headroom for crafting MBIM header */ - if (skb_cow_head(skb, sizeof(struct mbim_tx_hdr))) { + if (skb_cow_head(skb, __struct_size(mbim_hdr))) { dev_kfree_skb_any(skb); return NULL; } =20 - mbim_hdr =3D skb_push(skb, sizeof(struct mbim_tx_hdr)); + mbim_hdr =3D skb_push(skb, __struct_size(mbim_hdr)); =20 /* Fill NTB header */ nth16 =3D &mbim_hdr->nth16; @@ -133,12 +134,11 @@ static struct sk_buff *mbim_tx_fixup(struct sk_buff *= skb, unsigned int session, /* Fill the unique NDP */ ndp16 =3D &mbim_hdr->ndp16; ndp16->dwSignature =3D cpu_to_le32(USB_CDC_MBIM_NDP16_IPS_SIGN | (session= << 24)); - ndp16->wLength =3D cpu_to_le16(sizeof(struct usb_cdc_ncm_ndp16) - + sizeof(struct usb_cdc_ncm_dpe16) * 2); + ndp16->wLength =3D cpu_to_le16(struct_size(ndp16, dpe16, 2)); ndp16->wNextNdpIndex =3D 0; =20 /* Datagram follows the mbim header */ - ndp16->dpe16[0].wDatagramIndex =3D cpu_to_le16(sizeof(struct mbim_tx_hdr)= ); + ndp16->dpe16[0].wDatagramIndex =3D cpu_to_le16(__struct_size(mbim_hdr)); ndp16->dpe16[0].wDatagramLength =3D cpu_to_le16(dgram_size); =20 /* null termination */ @@ -584,7 +584,7 @@ static void mhi_mbim_setup(struct net_device *ndev) { ndev->header_ops =3D NULL; /* No header */ ndev->type =3D ARPHRD_RAWIP; - ndev->needed_headroom =3D sizeof(struct mbim_tx_hdr); + ndev->needed_headroom =3D struct_size_t(struct mbim_tx_hdr, ndp16.dpe16, = 2); ndev->hard_header_len =3D 0; ndev->addr_len =3D 0; ndev->flags =3D IFF_POINTOPOINT | IFF_NOARP; --=20 2.43.0