From nobody Mon Dec 1 22:02:39 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 7761F224AF7; Thu, 27 Nov 2025 03:12:09 +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=1764213132; cv=none; b=E2uQgCrrn74fX0f9F+Jf5ng7ECH+Yvrb60WPTl8+g9BQ7AdV8eZWQjtakO3n+FT2rmgduEp504shwCVqeuwLjQ48xCeRHL0Tk4v44mlrvW834oY8KgLpHpVqMqSUyNkM/IuT129llYHMDf7Znc7tVZc6EISZ1MJ417JfMlW6jqw= ARC-Message-Signature: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1764213132; c=relaxed/simple; bh=RiG8ocl+oskfHKP1fdxflSJbEMY4ORST7J8gciT7bkA=; h=Date:From:To:Cc:Subject:Message-ID:MIME-Version:Content-Type: Content-Disposition; b=Q2Icv7MuhEMnvzSuBOzKr3tNDx38Yl7p4Q6LwtwH3DQbiUliD4slMjKc80TUxQZG5I1/8JbPwgTU9m0ExisGczOHyPBFdizxxUjEQnywKXXOcLP0SIxtffm6JKpdCEWWZeo5rio17Bt8Qelw3rA9QgLQH2rC+QNTuR76GhmtGpI= ARC-Authentication-Results: i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=mK0hwf7f; 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="mK0hwf7f" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 6DD0DC4CEF7; Thu, 27 Nov 2025 03:12:06 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1764213128; bh=RiG8ocl+oskfHKP1fdxflSJbEMY4ORST7J8gciT7bkA=; h=Date:From:To:Cc:Subject:From; b=mK0hwf7f8lFRIv5+es/aYemkjY0hb5VlC3ROc4uBKNtpTM7lR+DcDHn4XE9QhsbJe GSDVMQC68wkZQvBgDaS+10C2YKL398zPpBwuoQnmge1O+XxAlMPxJ4HVC2Ie11odCL sdMzOIcgPumd0+IZq4ec7nTU9gJTtUcyzK7l5ECYMEHhMkkUKwNxqo6kZT02OouHym W4Wvah0uEbGUge/A31k1ZK/JQAdDOeHLTOqZQoXHcOPovJZ5A1APL8ZUAxSWXlZgIa jQlGShAnqPXOx7gpS9Qiss+19Ad8LfAfl/jMvlkr1tK4Rs5rDHXln5sgfeCzY5MB/P YhTr/d5IMwULw== Date: Thu, 27 Nov 2025 12:12:03 +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 v3][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] Reviewed-by: Loic Poulain Signed-off-by: Gustavo A. R. Silva --- Changes in v3: - Avoid 80+ char line. - Add RB tag. Changes in v2: - Add code comment to prevent people from adding new members after flex struct member `struct usb_cdc_ncm_ndp16 ndp16;` - Link: https://lore.kernel.org/linux-hardening/aSUwOtiDMYA8aSC3@kspp/ v1: - Link: https://lore.kernel.org/linux-hardening/aSUubvYfGJ-BIeDq@kspp/ drivers/net/wwan/mhi_wwan_mbim.c | 17 +++++++++-------- 1 file changed, 9 insertions(+), 8 deletions(-) diff --git a/drivers/net/wwan/mhi_wwan_mbim.c b/drivers/net/wwan/mhi_wwan_m= bim.c index c814fbd756a1..daf07ef86b2b 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 +584,8 @@ 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