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 B673B36AB46 for ; Thu, 17 Sep 2026 01:33:18 +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=1789608799; cv=none; b=VDqGHS/S7uMWdKemhEnPrIhD0j3MSxb/sWQLlRbdnfgDVeOfZt7rDI3yynxOIqiYUg+8hnSOSkau0WI/Q8B8AsP2HIwDg2cbwyRYFHQCU4r3uDjg6zSL2dPCQjEyYJMxoUxr75IFEcSfyRk8+80FE6CzbDRK2UmOputTnK46DAQ= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1789608799; c=relaxed/simple; bh=5uJXOsAGI26zMxQiXCLQVePNGJ8Kw3N51oPqxXWJR3g=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=LTU+sm1XvKd0kBgqBivjuzHAXFqLFqjtnFtAzg8uNSBCQ49HyyqU6PtD2WW5L1U0apQEq20g5IEAjmcghvh287an8jtW/yVnMv3aDevpbqhw14WmHz5uPxjhuCmG5TXDyMDe7D4WH3gr10hUgzJnqxydF1UifUm+CnZurEuz31I= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=DZ/2zFE3; 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="DZ/2zFE3" Received: by smtp.kernel.org (Postfix) with ESMTPSA id EA45B1F00893; Thu, 17 Sep 2026 01:33:17 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=kernel.org; s=k20260515; t=1789608798; bh=/oJltyoinxOIWnsx74wilMed7PLIgGjtwPR+dDxud9o=; h=From:To:Cc:Subject:Date:In-Reply-To:References; b=DZ/2zFE3TStSxam1egmXastbOkvMG7PN6Dv1npnHj0xMSvnlBgjo/6syAjJWIeZDH gCX4Y21KI0t9ULd40ZqiLHRpaHyH9DJFumADQPLdq1JnarkPAriRdi9PY+D93n1N71 vy9L87/hWSoqrMiThOXDtrywrkcVlKqaf5ulu5QnktCaqwMdvRf+Ys+Zuu3PeUQBgs m2hsJfZetQWM6L1SGm16Wh2f8JQvbrxNsHD2Y0jTQBMu4kD2UOGwO34MkhszjDzJJw 7xh9gQCri7NpDCARTyLOm9rsLISaFkBtiMhHDxfOaMeGmOVtvLNzEvsZtXSUtO0vYk 4SUNfAgGZiljg== From: Sasha Levin To: stable@vger.kernel.org Cc: Chengfeng Ye , Pablo Neira Ayuso , Sasha Levin Subject: [PATCH 5.15.y 5/5] netfilter: cttimeout: prevent UAF during module unload Date: Wed, 16 Sep 2026 21:33:13 -0400 Message-ID: <20260917013313.3594807-5-sashal@kernel.org> X-Mailer: git-send-email 2.53.0 In-Reply-To: <20260917013313.3594807-1-sashal@kernel.org> References: <2026091646-antonym-acid-ca2a@gregkh> <20260917013313.3594807-1-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 9eef304bd699e..31a1f6ff68d3f 100644 --- a/net/netfilter/nfnetlink_cttimeout.c +++ b/net/netfilter/nfnetlink_cttimeout.c @@ -665,9 +665,9 @@ 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