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 CD1B94D178F; Thu, 17 Sep 2026 17:44:16 +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=1789667058; cv=none; b=ap0bux3guuDwSch2LB0XG2hgHTUOAcxfcZwB71EKHrkvFRhziaVmqGdn045O4A+DgYtm/J2Cji6rhjL2zLcqk4mU4MNXNCwWlyPB3YFUYgS08rwEibZ4E4uzzCSjZJu3eozhmpuBAB6xI4yuzwczLLufKSAYfg8dHBVo26aRX+s= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1789667058; c=relaxed/simple; bh=nDjYpbtZ2/7VPLQ/O4zlFzBmmEeYC7BEEQbHHXhXVis=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=kiKZNVtmSOKAc7naAk40u7Wdsan1+IbuxFLFjqxuHT6OC/+7+Wijpdskt3DTnQ8fBiBlOxp7tavpwDBphHryTl77HbX/Xb3IAT/IpjWYLepBK3SEUCU8/uu3hlfTn//GiUvhh7j38nXalpCo+792mVOnfeOmZNr0cSnyd9ANJp8= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b=erYwVspO; arc=none smtp.client-ip=100.103.45.18 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b="erYwVspO" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 327BB1F000FF; Thu, 17 Sep 2026 17:44:16 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linuxfoundation.org; s=korg; t=1789667056; bh=GoazHumqGw7VrlnqMpaar6Zun7FC9UhYY3/LCQCWBXo=; h=From:To:Cc:Subject:Date:In-Reply-To:References; b=erYwVspOdGRVfG8MeqRxN8xZvQFLG5Fs6hC3KXI4fNtLROhId8PLFPLCww5GcLdvY hn2KyoN53m6OMhUy++RRZQlub0Vv+Wm7d6qR7EisFYL9FrttwDGqY6PgqZJ+hp1ASi qWVAAcAe7hRFM5C3a+w3t8bxfnvVyoovaW78TDvQ= From: Greg Kroah-Hartman To: stable@vger.kernel.org Cc: Greg Kroah-Hartman , patches@lists.linux.dev, Chengfeng Ye , Pablo Neira Ayuso , Sasha Levin Subject: [PATCH 6.18 1214/1250] netfilter: cttimeout: prevent UAF during module unload Date: Thu, 17 Sep 2026 16:16:49 +0100 Message-ID: <20260917151625.191043268@linuxfoundation.org> X-Mailer: git-send-email 2.55.0 In-Reply-To: <20260917151551.901433442@linuxfoundation.org> References: <20260917151551.901433442@linuxfoundation.org> User-Agent: quilt/0.69 X-stable: review X-Patchwork-Hint: ignore Precedence: bulk X-Mailing-List: patches@lists.linux.dev List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit 6.18-stable review patch. If anyone has any objections, please let me know. ------------------ 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 Signed-off-by: Greg Kroah-Hartman --- net/netfilter/nfnetlink_cttimeout.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) --- 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);