From mboxrd@z Thu Jan 1 00:00:00 1970 Authentication-Results: smtp.subspace.kernel.org; arc=pass header.oldest-pass=0 smtp.remote-ip=165.173.182.15 ARC-Seal: i=2; d=subspace.kernel.org; s=arc20261015; a=rsa-sha256; cv=pass; t=1792502991; b=Q4kf7re5wHm8oWCcxmvpq3jnmcX01H0ihH2kKCQMd1kKvJsfIozwuQtqU9HkChnon/7d yYrw29xpOUpzk2tgdKar+05X3Pv2GixAPychK4ZuYuzm6HhDwnx7KFrQwR5j3SS2I1DHi CtTCZOtQfYdjv3IGqUvWx0Bfesr5ThoeZeFM8U3C1fbZkrqPo9RSBG3Lt8HGAkZDvLaIc QwAdeJoch2zYrQoSWc6RK5Fifo7ciCYIMyvjENaPtqOeRww/BvDjAeXYL4Azp2Hitko6J 8geDtRMdXQdCShEMCOFk68/TCXDgF8mXl4Ca8qLzIVm493hxhA2iYJJrbVdjMYxKLiA== ARC-Message-Signature: i=2; d=subspace.kernel.org; s=arc20261015; a=rsa-sha256; c=relaxed/relaxed; t=1792502991; h=DMARC-Filter:DKIM-Signature:Received:From:To:Cc:Subject:Date: Message-ID:X-Mailer:MIME-Version:Content-Transfer-Encoding: X-ZohoMailClient; bh=faqcXlf3am5ayTseexfa5cqCZPxHait6Gq7hGss05/o=; b=u1YDx3wi/TJAybhpA4ffwn2g5W8vdF3Lf6xVkGj5aWvXQoVok8tHDNxTjKKJLVSshpay xqwP2ljgEOCjc1aJ7KyM9s495U7XhpiZuTAwWf/YfwVMeJLlyoygNA6YNI4CB56kYLP08 a4lnF26zIdAU6w6oa73wZXgBbGRhcbKd8WtkL43alKo6ymnrjmmaFiXxGNimKhQEMNxDO wk0X3o4CvME9REbCfkNQS0BnETvm3CDOtoUUIyJUXvlXkazgbyHBFyZUaixChpsa1eIGi njyk0Zy0dtujjO1Y7DySML61BT9zJiU3sXvlKqlFNmCIPi/79wdAAPYees/CNXv9UBw== ARC-Authentication-Results: i=2; smtp.subspace.kernel.org; dmarc=none header.from=laveeshbansal.com; spf=pass smtp.mailfrom=laveeshbansal.com; dkim=pass header.d=laveeshbansal.com header.i=laveeshb@laveeshbansal.com header.a=rsa-sha256 header.s=zoho header.b="R2ntOH/z"; arc=pass header.oldest-pass=0 smtp.remote-ip=165.173.182.15 Received: from sender5-op-o15.zoho.com (sender5-op-o15.zoho.com [165.173.182.15]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature ECDSA (prime256v1)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 8546760A2626; Tue, 20 Oct 2026 13:29:50 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.4.2 smtp.subspace.kernel.org 8546760A2626 Authentication-Results: smtp.subspace.kernel.org; dmarc=none (p=none dis=none) header.from=laveeshbansal.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=laveeshbansal.com Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key, unprotected) header.d=laveeshbansal.com header.i=laveeshb@laveeshbansal.com header.a=rsa-sha256 header.s=zoho header.b=R2ntOH/z ARC-Seal: i=1; a=rsa-sha256; t=1792502973; cv=none; d=zohomail.com; s=zohoarc; b=EuD8bntbTMkMeHimUzqDTvJkp5gf2DKwzcTvVhBYZRbLdSFKytmJR1eJAFbIhoWbf1Tf7+gAjOjBPp/L2+eOihyXKpqlMe4JmcDn6lWy2Ajj9DQLaApTgrVzO7Nod2YCobHoqu2HRm54UbAxE9L+qHReVfOE3+2Jfx6UaqEleP0= ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=zohomail.com; s=zohoarc; t=1792502973; h=Content-Transfer-Encoding:Cc:Cc:Date:Date:From:From:MIME-Version:Message-ID:Subject:Subject:To:To:Message-Id:Reply-To; bh=faqcXlf3am5ayTseexfa5cqCZPxHait6Gq7hGss05/o=; b=E8c7QAJxpNL6PofIIb4S7ospQ8SfgCZ7q/Jahia6lK97gqRLA6q7/tfY3GrnzRI6XIVs5YdwWSnrLMNALcNJcKdA0Lkvf5tU6WJAE9e0PpAqAWUpw7fUSrfyUu1CoaPhhCA3GQUni0mBVxwsLN2d/Z7FxZTvxwnGSimQZuMXKKY= ARC-Authentication-Results: i=1; mx.zohomail.com; dkim=pass header.i=laveeshbansal.com; spf=pass smtp.mailfrom=laveeshb@laveeshbansal.com; dmarc=pass header.from= DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; t=1792502973; s=zoho; d=laveeshbansal.com; i=laveeshb@laveeshbansal.com; h=From:From:To:To:Cc:Cc:Subject:Subject:Date:Date:Message-ID:MIME-Version:Content-Transfer-Encoding:Message-Id:Reply-To; bh=faqcXlf3am5ayTseexfa5cqCZPxHait6Gq7hGss05/o=; b=R2ntOH/z5zrP4NH6DRLJy731eTb0c/6yaJH66gxC0lYeKUy7fmHPgdS3xOV28yaI DNunMDYmzgh3Iirhx6vnJa9w2Lkt7SYTd0Qn3DlJUaC7WJLpdCTTcEns3oMnI7wIYO4 UsUo1etcDjWFji08Hl2zhl8IUd4hzRIqexcSE+fI= Received: by smtp.zohomail.com with SMTPS id 1792502972236450.06009507923477; Tue, 20 Oct 2026 06:29:32 -0700 (PDT) From: Laveesh Bansal To: Pablo Neira Ayuso , Florian Westphal Cc: Nikolay Aleksandrov , Ido Schimmel , netfilter-devel@vger.kernel.org, coreteam@netfilter.org, bridge@lists.linux.dev, netdev@vger.kernel.org Subject: [PATCH nf v2] netfilter: bridge: use DEBUG_NET_WARN_ON_ONCE in nf_ct_bridge_refrag() Date: Tue, 20 Oct 2026 06:29:11 -0700 Message-ID: <20261020132911.43696-1-laveeshb@laveeshbansal.com> X-Mailer: git-send-email 2.54.0 X-Mailing-List: netdev@vger.kernel.org List-Id: List-Post: List-Help: List-Subscribe: List-Unsubscribe: List-Owner: Precedence: list MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-ZohoMailClient: External nf_ct_bridge_refrag() warns when skb->protocol is neither IPv4 nor IPv6. A vlan filtering bridge can get there with a vlan ethertype: if the protocol of the tag of a frame differs from the vlan_protocol of the bridge, br_allowed_ingress() moves the tag back into the packet after NF_BR_PRE_ROUTING, where bridge conntrack has already defragmented it. Anyone who can send fragments into a port of such a bridge can trigger the warning, which takes the machine down with panic_on_warn. The packet is dropped either way, so only warn on kernels built with CONFIG_DEBUG_NET. This only avoids the warning. Such fragmented packets are still dropped. syzbot reported the warning. It keeps triggering on CONFIG_DEBUG_NET kernels until the vlan tag is handled, which is left for a follow-up: https://syzkaller.appspot.com/bug?extid=a8ba738fe2db6b4bb27f Fixes: 3c171f496ef5 ("netfilter: bridge: add connection tracking system") Assisted-by: LLM Signed-off-by: Laveesh Bansal --- v2: - Reduced to DEBUG_NET_WARN_ON_ONCE(), as suggested by Pablo. Handling the vlan tag and the selftest will follow for nf-next. - Dropped Reported-by, Closes and Cc: stable. This does not fix the syzbot report, its config has CONFIG_DEBUG_NET=y. - Only the commit that added the warning is listed in Fixes:. v1: https://lore.kernel.org/r/20261020005403.38212-1-laveeshb@laveeshbansal.com net/bridge/netfilter/nf_conntrack_bridge.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/net/bridge/netfilter/nf_conntrack_bridge.c b/net/bridge/netfilter/nf_conntrack_bridge.c index b5444335b86f..8c83dc05114b 100644 --- a/net/bridge/netfilter/nf_conntrack_bridge.c +++ b/net/bridge/netfilter/nf_conntrack_bridge.c @@ -358,7 +358,7 @@ nf_ct_bridge_refrag(struct sk_buff *skb, const struct nf_hook_state *state, nf_br_ip6_fragment(state->net, state->sk, skb, &data, output); break; default: - WARN_ON_ONCE(1); + DEBUG_NET_WARN_ON_ONCE(1); return NF_DROP; } -- 2.43.0