From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-alma10-1.taild15c8.ts.net [100.103.45.18]) (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 1967A4E66CE for ; Wed, 16 Sep 2026 23:42:18 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=100.103.45.18 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1789602141; cv=none; b=mGVYZvRgY/D8ddQ9M0pmvmhAF5ZoP8GSEEtmxCGjexexY3xDTSBrjb1g/aeyV5yyQShJMvbPo32O6bkoIcPJOjGD0Xnp66zEpJYcS0EBwRBPph6YMaA49NaWJfruh7y797Vu1GnKINm9pqx/+YRh23hMpC6iX6giUtp6Qebu/XA= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1789602141; c=relaxed/simple; bh=PT1L1r4Ij4RYTf0s44lRTEuG8azTmzAER5kPfI/Z22E=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=MT6zsUqA6hDf/Raho3O9oecLFdybzAH+vLgu/VZvxg5SlBLvzhSbUr6qcAmxKSf7KN/OOlj/7u7zCjfjJPW+jRUNOM5JnCFZK06L9PjWT1EkrdoiIbowbZ7JXuyoTPCsoUybZpw0Zg2sjrYZOoOGRDjELWJIHO24NUvKyMweJ+A= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=EKJWwYFn; arc=none smtp.client-ip=100.103.45.18 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b="EKJWwYFn" Received: by smtp.kernel.org (Postfix) with ESMTPSA id BC7621F00893; Wed, 16 Sep 2026 23:42:17 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=kernel.org; s=k20260515; t=1789602138; bh=rkhswP0gplLmYZTHMffooCA2bJmmaHbSAJXe8DkTPYk=; h=From:To:Cc:Subject:Date:In-Reply-To:References; b=EKJWwYFn5PBtC+UDv+GRtQfq3U6qj/V74w8Rs/phCIdlKOduP7vbypiEI22zVjJrQ IiU61qs/B6DVf4KmCTbMUSC7YdxZdV6n7vIw7zQOFG4gUUx8bSk0Zjw2QGD+MgYqrb /RHyADU3No1/U6xGmnH4AQjg2ATQLUgJ9WhhbtmHvQgmNHK722o5H52MzTwvihdr/d DryJqYUDs36bQfUitoGV98XKegDP2w4PHsjHf7xQGSwvYshjEeAhlUzjCAUvb4wo5c z1a7VGMEZu1I8A6FkGwT0ZqGh+ODJIMaszr/lgivZEd34EuVQ8+kOvIEMTE1UkFrxg 23mJpl0UHDC4w== From: Sasha Levin To: stable@vger.kernel.org Cc: Chengfeng Ye , Pablo Neira Ayuso , Sasha Levin Subject: [PATCH 6.18.y 2/2] netfilter: cttimeout: prevent UAF during module unload Date: Wed, 16 Sep 2026 19:42:15 -0400 Message-ID: <20260916234215.3296425-2-sashal@kernel.org> X-Mailer: git-send-email 2.53.0 In-Reply-To: <20260916234215.3296425-1-sashal@kernel.org> References: <2026091639-unmade-pouch-5365@gregkh> <20260916234215.3296425-1-sashal@kernel.org> Precedence: bulk X-Mailing-List: stable@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit From: Chengfeng Ye [ Upstream commit fec9b1de0d02de8dafa3cc344bcb91cf28660643 ] 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 Signed-off-by: Sasha Levin --- 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 c87335d78dfa0..564e4642467dc 100644 --- a/net/netfilter/nfnetlink_cttimeout.c +++ b/net/netfilter/nfnetlink_cttimeout.c @@ -654,9 +654,9 @@ 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); -- 2.53.0