From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from mail-ej1-f46.google.com (mail-ej1-f46.google.com [209.85.218.46]) (using TLSv1.2 with cipher ECDHE-RSA-AES128-GCM-SHA256 (128/128 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 3731D30AAB8 for ; Tue, 24 Feb 2026 06:53:16 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=209.85.218.46 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1771915997; cv=none; b=BaqORi1Nd6WyJwOkCZlSXQyZ1pEn40YsmxhexPUUU+Xc3ZVAIkfgcdDf8pVE06/B3FCfMXBRsyOXWCqR/oLGMCM8aJjK3Gvq36/NvMIzeCpoAkCBdwJ9kwg5iqB/jx4KIvehJbPhKmStuC5TwuYaS0PYcMBtvfmkNphcxKTwERo= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1771915997; c=relaxed/simple; bh=s5w90tjQkJYYzbC3vOYs6oXg7h6S7OJfWNsP/+o7GlI=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=NQAtzrEHjSc4IxdCueIM3a1v0ossVc8vQpGwJ5DWARRs1VNNJLWkintATkZ8DKe1Y8Tg83PKl3L19t6Xq1BV/TBCKNEMtkzJ3TGJg2ZV/zmbziiI3uS2E7NPfLFn7K9gWfAjFnwQaDrKM125AUCuSOHfpCrfjDpdbXhKb+tBzEY= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=gmail.com; spf=pass smtp.mailfrom=gmail.com; dkim=pass (2048-bit key) header.d=gmail.com header.i=@gmail.com header.b=hhk52DEA; arc=none smtp.client-ip=209.85.218.46 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=gmail.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=gmail.com Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=gmail.com header.i=@gmail.com header.b="hhk52DEA" Received: by mail-ej1-f46.google.com with SMTP id a640c23a62f3a-b886fc047d5so818368166b.3 for ; Mon, 23 Feb 2026 22:53:16 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20230601; t=1771915995; x=1772520795; darn=vger.kernel.org; h=content-transfer-encoding:mime-version:references:in-reply-to :message-id:date:subject:cc:to:from:from:to:cc:subject:date :message-id:reply-to; bh=TWLpgkJWRF7bEw/Zu91fLz8PWNtrMB/wH+bAcmEPFvw=; b=hhk52DEAYcaUOc50p/Tu45xjiuPLoKFj42Up34NHhs3VpxGny8pv+L7DfhWTffPxFk h3u5gnEfeUm9z9a20Viy5ru4n9nNQl92hBJNmpRopaCr1UCN5/hFDR/Gres9fAY/0L7o EE5f8kXA5UhJSSt09n1ELOlW31KkYfsNmlPRnSj3RKyiiWXywx8DHKXxvdlxQ/JgIgmO NryzkJWnm4tDJLuxjU/jB3dvGl0sWpkGluRJ1DoQUaFakX28EhsejcJSBrcu51zmQqzt bhOJeXeKtSFSv9kSGfdIzQ0zdJskS1aZHA/enpCDlgTRVqX0LHrrRLT5ZHAQpv1emvHa mp3w== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20230601; t=1771915995; x=1772520795; h=content-transfer-encoding:mime-version:references:in-reply-to :message-id:date:subject:cc:to:from:x-gm-gg:x-gm-message-state:from :to:cc:subject:date:message-id:reply-to; bh=TWLpgkJWRF7bEw/Zu91fLz8PWNtrMB/wH+bAcmEPFvw=; b=B4EDeDC2xZUAi49bu7tSZiRE9iSRlMJOiQvS1T2igP3kPLvaD4Fz7rj+nfS8wwAI3h U0mr/FycLsRpLSnHAicm7OLaIM5wNmjbffmlyBmLc7rpdR/ku+yStqVIry3Vg1gq4cuR w2OBA34jVLXKozVDr4Rpl1LYm2Lx5nON6U3CbvaSS75CQZlJ/N0foo3Po8sVZNEom7iS wF6Q4TBXF9pyvh05tR2y9cujwNYqtpWhfEc0B6EIBLQ/6ZwIWdJw14R11oupPJIjqvnZ /LNgA++z9KscSFoYrR+LeV/p854lZt3hOZcRRLSQnYd6Y9e5n8bascBVAl+PdjmFisRu mupg== X-Forwarded-Encrypted: i=1; AJvYcCWW2AyO8inWD9j+ZIAHuifvLViQLpu4Miyo4klnes5l23h71v5SHHOoVWIfeNS2D2Re1Rn0kOx+LdJn7A2Q/Ak=@vger.kernel.org X-Gm-Message-State: AOJu0Yxuw9ohQFuxSKoAFbO9CZYxCCm1MGkaIaK+4E75/Z9uiVKpnL3K 4dnxuVOZLu0F4eDbzCPUcNSy1cs3NuROwoY4k1oN+fn9KwDnw9myHO1O1WFlJw== X-Gm-Gg: AZuq6aKuVvCR0Jy5wOFdHJJQXU9zFGTSKgGDS8ofDW11QOFIrQCFupXdeI1ek/5gt+/ IGifOgPvhML6r58k+vkUunxEvXihatHfEBNltEs97W+2Bvk32pD6ZljBSdcosHzwuWx+ZTMBqQ4 tijRvQYVuWsFpmB1OJdUuDaarEe/ZB3XvtUNDPAisvD/AOqbqKD34BlHg38SE4Ajc3kPSCfzO0q guvgHaYMn06CPnesOnYBV5nVybQVZmN0EkYhXByKIJ+yjgC4sA/d8eBzI4IegPeAZO/vtJE1CqX 5V8eoEJBk//Y5CvmBNKSqShGQUBkeNrBmAucudAwHYQP117M7c5Hd5ZyZ9THDYft02leofW6Ovg KvdQ40WyHf9FLESlPGvrB5c0JmPsRc+DEmnt1scfqFkMh+CAOEC5dUOqHrZw0faQ4BfMZ71alOA VvMYNB9Xdw17Q24hH9TisfAwVqzHwfJBpoeeJFENFaLFxKGEVgZGNO0DNes8HiGSgCF8xNaCY7k KwE1YkBgwbFLsihYlvFa1q1AOqPz9MAfhMu3Q2aEJvSWV5wwAX7FgQ= X-Received: by 2002:a17:906:4455:b0:b8f:8ff5:45d with SMTP id a640c23a62f3a-b9081c19dd5mr506369666b.53.1771915994218; Mon, 23 Feb 2026 22:53:14 -0800 (PST) Received: from eric (2001-1c00-020d-1300-1b1c-4449-176a-89ea.cable.dynamic.v6.ziggo.nl. [2001:1c00:20d:1300:1b1c:4449:176a:89ea]) by smtp.gmail.com with ESMTPSA id 4fb4d7f45d1cf-65eaba13866sm3096698a12.18.2026.02.23.22.53.12 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Mon, 23 Feb 2026 22:53:13 -0800 (PST) From: Eric Woudstra To: Michal Ostrowski , Andrew Lunn , "David S. Miller" , Eric Dumazet , Jakub Kicinski , Paolo Abeni , Pablo Neira Ayuso , Florian Westphal , Phil Sutter , Simon Horman , Nikolay Aleksandrov , Ido Schimmel Cc: netdev@vger.kernel.org, netfilter-devel@vger.kernel.org, bridge@lists.linux.dev, Eric Woudstra , Kees Cook Subject: [PATCH v19 nf-next 1/5] net: pppoe: avoid zero-length arrays in struct pppoe_hdr Date: Tue, 24 Feb 2026 07:53:02 +0100 Message-ID: <20260224065307.120768-2-ericwouds@gmail.com> X-Mailer: git-send-email 2.53.0 In-Reply-To: <20260224065307.120768-1-ericwouds@gmail.com> References: <20260224065307.120768-1-ericwouds@gmail.com> Precedence: bulk X-Mailing-List: netfilter-devel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit Jakub Kicinski suggested following patch: W=1 C=1 GCC build gives us: net/bridge/netfilter/nf_conntrack_bridge.c: note: in included file (through ../include/linux/if_pppox.h, ../include/uapi/linux/netfilter_bridge.h, ../include/linux/netfilter_bridge.h): include/uapi/linux/if_pppox.h: 153:29: warning: array of flexible structures It doesn't like that hdr has a zero-length array which overlaps proto. The kernel code doesn't currently need those arrays. PPPoE connection is functional after applying this patch. Reviewed-by: Nikolay Aleksandrov Reviewed-by: Kees Cook Signed-off-by: Eric Woudstra --- drivers/net/ppp/pppoe.c | 2 +- include/uapi/linux/if_pppox.h | 4 ++++ 2 files changed, 5 insertions(+), 1 deletion(-) diff --git a/drivers/net/ppp/pppoe.c b/drivers/net/ppp/pppoe.c index 4275b393a454..7900cc3212a5 100644 --- a/drivers/net/ppp/pppoe.c +++ b/drivers/net/ppp/pppoe.c @@ -885,7 +885,7 @@ static int pppoe_sendmsg(struct socket *sock, struct msghdr *m, skb->protocol = cpu_to_be16(ETH_P_PPP_SES); ph = skb_put(skb, total_len + sizeof(struct pppoe_hdr)); - start = (char *)&ph->tag[0]; + start = (char *)ph + sizeof(*ph); error = memcpy_from_msg(start, m, total_len); if (error < 0) { diff --git a/include/uapi/linux/if_pppox.h b/include/uapi/linux/if_pppox.h index 9abd80dcc46f..29b804aa7474 100644 --- a/include/uapi/linux/if_pppox.h +++ b/include/uapi/linux/if_pppox.h @@ -122,7 +122,9 @@ struct sockaddr_pppol2tpv3in6 { struct pppoe_tag { __be16 tag_type; __be16 tag_len; +#ifndef __KERNEL__ char tag_data[]; +#endif } __attribute__ ((packed)); /* Tag identifiers */ @@ -150,7 +152,9 @@ struct pppoe_hdr { __u8 code; __be16 sid; __be16 length; +#ifndef __KERNEL__ struct pppoe_tag tag[]; +#endif } __packed; /* Length of entire PPPoE + PPP header */ -- 2.53.0