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 7479151FCD5; Mon, 7 Sep 2026 17:17:44 +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=1788801466; cv=none; b=OBqQbHSO1hdyTJfFWoczxlESxlW9AH2rHn89803jObPDTuwQKst5u4I9SoWN14wBvNAQ5ryq6Uwv7iFQ1dSV6dabTKFqe7Gbwd/gvT8OI3Flhj+EMTnlQIO4JYQIy4vL97BCY4xtAaJjMjRXJKiriHdCoGd5+0iBudJU+Ueu6vw= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1788801466; c=relaxed/simple; bh=KDMZxKBokX/eFmwjI6AiPYr9lz9zdu6GtHeQGtGseKM=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=Tj05VeLmxCuIS85B39ezbyaqNz/HtsuPwpg5JbeKdRqviT62/oV+5fL94u6UUI0/INsktiCKZYzSU+lyk9eQeqrXcG7F+Rid7K5BhWuMCurQPnRpP8o88rvL++riIfPoyORNN34zjcm7ZPbna2CurjXp64jUVlm5pGjJUSYcOJc= 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=rBcSAe0t; 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="rBcSAe0t" DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=netfilter.org; s=2025; t=1788801462; bh=+Qvb7ZF0hgN+b8Z8TtazAeZH6daOLVVsMU/uL6SjuRs=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=rBcSAe0t/hUuksXgymcIXUZLS4gdJw6btyHaq1f8B9J9oRhuUoYdIGyKirpdhsSSy objSmrGrcAL3WkBm9zBKe0OKRty0nbmI3km4N3IGpoTt8IaATRWWajCAXxOUIFBHj9 ch0f8TBDR2CYgafHrECet4WEmZbQHceSdGhBY8jcguIa/3kXqkLjwdRLDaK031zKLC r4tI4qlF2jZzf6Mg1J0t16b685D2x+eoBO0aENrJV62yIIfWqo3e7aGLpDaIuQFFIZ OQllpoJIpVBjbpVcUyv2KXG2s7JaFfNhnXv2A7+sxgfvjHrkZRNhuNGeqBTGPDNnR9 DXv9JZ6v78fmQ== Received: from localhost.localdomain (mail-agni [217.70.190.124]) by mail.netfilter.org (Postfix) with ESMTPSA id E78DD607D3; Mon, 7 Sep 2026 19:17:41 +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 4/9] netfilter: cttimeout: prevent UAF during module unload Date: Mon, 7 Sep 2026 19:17:27 +0200 Message-ID: <20260907171732.1407739-5-pablo@netfilter.org> X-Mailer: git-send-email 2.47.3 In-Reply-To: <20260907171732.1407739-1-pablo@netfilter.org> References: <20260907171732.1407739-1-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: Chengfeng Ye nf_ct_set_timeout() protects the timeout hook dereference and policy lookup with rcu_read_lock(). cttimeout_exit(), however, unregisters the per-net operations before it clears the hook. This allows the following interleaving: CPU 0 CPU 1 cttimeout_exit() nf_ct_set_timeout() unregister_pernet_subsys() rcu_read_lock() kfree(pernet) h = nf_ct_timeout_hook h->timeout_find_get() nfct_timeout_pernet() The hook still points to ctnl_timeout_find_get() when CPU 1 looks up the already freed per-net timeout list. KASAN reported: BUG: KASAN: slab-use-after-free in ctnl_timeout_find_get Read of size 8 by task poc/90 Call Trace: ctnl_timeout_find_get+0x271/0x2a0 [nfnetlink_cttimeout] nf_ct_set_timeout+0x7b/0x3c0 xt_ct_tg_check+0x724/0xb20 xt_check_target+0x234/0xa90 do_ipt_set_ctl+0x570/0x1270 Allocated by task 89: __kmalloc_noprof+0x16e/0x460 ops_init+0x6d/0x420 register_pernet_operations+0x2f6/0x670 Freed by task 91: kfree+0x131/0x390 ops_undo_list+0x3d4/0x730 unregister_pernet_operations+0x232/0x490 unregister_pernet_subsys+0x1c/0x30 cttimeout_exit+0x52/0x970 [nfnetlink_cttimeout] Clear the hook and wait for existing readers before unregistering the per-net operations. This blocks new policy lookups and ensures readers that observed the hook finish before the per-net storage is freed. Fixes: ebfbe67568a7 ("netfilter: cttimeout: use net_generic infra") Cc: stable@vger.kernel.org Signed-off-by: Chengfeng Ye Signed-off-by: Pablo Neira Ayuso --- net/netfilter/nfnetlink_cttimeout.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/net/netfilter/nfnetlink_cttimeout.c b/net/netfilter/nfnetlink_cttimeout.c index 66c2016f6049..132c02ac7c4e 100644 --- a/net/netfilter/nfnetlink_cttimeout.c +++ b/net/netfilter/nfnetlink_cttimeout.c @@ -652,9 +652,9 @@ static void __exit cttimeout_exit(void) { nfnetlink_subsys_unregister(&cttimeout_subsys); - unregister_pernet_subsys(&cttimeout_ops); RCU_INIT_POINTER(nf_ct_timeout_hook, NULL); synchronize_net(); + unregister_pernet_subsys(&cttimeout_ops); } module_init(cttimeout_init); -- 2.47.3