From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from mail.netfilter.org (mail.netfilter.org [217.70.190.124]) (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 86D7A511180; Wed, 16 Sep 2026 23:17:10 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=217.70.190.124 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1789600631; cv=none; b=sFh31Zrq6nvYMBc37WVO6gGCeDx5sEOrJL2+88XEhtpcOAvl+fah80jHEBfsTSsyAoOiJQTx3BIzZT0NfuroJq8aEqOCFkSSm0y+l7KevpvoBi/9uY3pOxgdzpAVXpmrTloLjFZ5V3MvTgLrBWg+vnYP1qS5wdBx4rxBRAc8LBQ= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1789600631; c=relaxed/simple; bh=2woUwebNozG9SC/ZhcyZWpi0EhdbBv0LkaCr2U7PIpg=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=bBD2NHDQ3iZL7myG1xKbGYdGsgAwy42dR5ulCtN27HjCvUJP4KDdzK4SyDaYYegIRTO9lCWM7IFoNfBkwIRWzPLwOzqxsn3py6fSAIWE15OxASriXkujtlUFm2+sIwQuO075T/dbYTG0r3qXv5AYnvhzf3iE5DT4yLaDtJ6yYMM= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=none (p=none dis=none) header.from=netfilter.org; spf=pass smtp.mailfrom=netfilter.org; dkim=pass (2048-bit key) header.d=netfilter.org header.i=@netfilter.org header.b=q/qA1fjN; arc=none smtp.client-ip=217.70.190.124 Authentication-Results: smtp.subspace.kernel.org; dmarc=none (p=none dis=none) header.from=netfilter.org Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=netfilter.org Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=netfilter.org header.i=@netfilter.org header.b="q/qA1fjN" DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=netfilter.org; s=2025; t=1789600628; bh=LfLDKDbros6AeCuQZJqhSAeSTHK42cKZ1cwPHtxZpqw=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=q/qA1fjNjigNj8TQbJBtwD3+qPnMmrsArAZ+ewyXBSQaXvtaXQPB3HGCYYDqgQ94x rhIuc/unkWOWMEhZ7HcqjZZtPDrcrdW+Vx52PpqRXT1zRAxS659vd0O5+zBtRXUo9G PxfTKAmgOrbHQDKN6xHMse1zVZT58vj30X46uWqX6iE4u7pTAj2BlK3R6Q7J/rVbBv GHADQ5FPFL3l76gS8WS7XRnTm4ekXjmvJbghAm9Cpjqeu66xYsacmcvLMuQp0wWFsh sLPM+Fp/X6kMEdis8xT0L1kQtt6nKtBNvOOECt+r2eKYyBbCwANwpr21TGANaw2fMS Dc0oXVDfapADA== Received: from localhost.localdomain (mail-agni [217.70.190.124]) by mail.netfilter.org (Postfix) with ESMTPSA id 13A416008E; Thu, 17 Sep 2026 01:17:08 +0200 (CEST) From: Pablo Neira Ayuso To: netfilter-devel@vger.kernel.org Cc: davem@davemloft.net, netdev@vger.kernel.org, kuba@kernel.org, pabeni@redhat.com, edumazet@google.com, horms@kernel.org, fw@strlen.de, ja@ssi.bg Subject: [PATCH net 09/10] net: remove WARN_ON_ONCE() from the dev_fill_forward_path() loop check Date: Thu, 17 Sep 2026 01:16:50 +0200 Message-ID: <20260916231652.127456-10-pablo@netfilter.org> X-Mailer: git-send-email 2.47.3 In-Reply-To: <20260916231652.127456-1-pablo@netfilter.org> References: <20260916231652.127456-1-pablo@netfilter.org> Precedence: bulk X-Mailing-List: netdev@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit From: Farhad Alemi ipip_fill_forward_path() and ip6_tnl_fill_forward_path() look up the route to the tunnel's remote endpoint and set ctx->dev to its device, which is the tunnel itself when that route resolves back to the tunnel. dev_fill_forward_path() then makes no progress and trips WARN_ON_ONCE(last_dev == ctx->dev) as soon as a flowtable tries to offload a flow through the tunnel. That routing loop is a configuration any CAP_NET_ADMIN user can set up, and ip_tunnel_xmit() and ip6_tnl_xmit() already treat it as a tx error, so remove the warning and just fail the walk, as commit 008e7a7c293b ("net: remove WARN_ON_ONCE when accessing forward path array") did for the path stack overflow. Fixes: ab427db17885 ("netfilter: flowtable: Add IPIP rx sw acceleration") Fixes: d98103575dcd ("netfilter: flowtable: Add IP6IP6 rx sw acceleration") Closes: https://lore.kernel.org/all/CA+0ovCgaRvbd0Udj70b2xxG8Cx3CaCpNhnf1V4RWQuDveZYZhA@mail.gmail.com/ Suggested-by: Pablo Neira Ayuso Assisted-by: Claude:claude-opus-5 syzkaller Signed-off-by: Farhad Alemi Signed-off-by: Pablo Neira Ayuso --- net/core/dev.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/net/core/dev.c b/net/core/dev.c index ecfbd72d5d1a..c67900354fa6 100644 --- a/net/core/dev.c +++ b/net/core/dev.c @@ -789,7 +789,7 @@ int dev_fill_forward_path(struct net_device_path_ctx *ctx, goto err_out; stack->num_paths++; - if (WARN_ON_ONCE(last_dev == ctx->dev)) + if (last_dev == ctx->dev) goto err_out; } -- 2.47.3