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 3E45C31B130 for ; Thu, 17 Sep 2026 00:26:06 +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=1789604768; cv=none; b=ZDGhBVTBmdtd7tgIwaroQo1/5UU3UZTG12tyg4myt6z7CPhiHsepXHzGCyelp+qhpDfAc1OIqRQnrHQnGcc0FW1gxaqrnlFyB8VJsVQiyhmudYN+uNJIHFt5/4+gVqZjLzM4NZXWM4jDEx799subsUcF9ZeMWdBeQD6/1xNIsqo= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1789604768; c=relaxed/simple; bh=n0MF1QZ3tQR4H9jki6JtblhnigGgAqXxY9C86u/OlzM=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=UlBKaz4MOevSIVgdRhBNx8s2Yz1LS7anMDlN6I9gH9eTVO+I0pd8A1a0AcfnB4qcTROsLdaHt2TLqArrG466Tycq/UsRrI3/Q8EwZLtMsiTV3bSO3w+Iig1Ywk6ZghAjMWC4W+Oqb5M9lsfyq//HAGRhMUzlRaq5ech45lWoQ+o= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=Z5cY7kxL; 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="Z5cY7kxL" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 87FFA1F0089A; Thu, 17 Sep 2026 00:26:05 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=kernel.org; s=k20260515; t=1789604766; bh=G4OQFvNOyW4fWjZYHDFyCpoKlh+vMGLuqkpw7CI95KA=; h=From:To:Cc:Subject:Date:In-Reply-To:References; b=Z5cY7kxLK+AeQ1K8UK2KTKp4EM/UbUmoqGIpoQzF3A3Bbj9+kgjOgOFUJpmurJu6S QnH4jBZ3625d0G4Buiq/M3SGrX7gcbJIrHSRa68vRS9Bj9ERbffB7fqtH0o7YjHQk+ m94GPZyPurPQXK303qd8QF5WLCZBoUOmMyNz7KIsWH4Gsf6OIGcdmCr/M3msdzPsuM L+eKNeTWGIISr8xKTgCJb+AeUG1n6XjFlP3yu4HQODdZTVaB53A8cL6JWwIJa6OSbY r15ombhTjTeW+AxDuZ5EPIHKkC8YF+Q6iNTEbXF+7GvC1HPpB19+n/IUgzDTkTj51x dX+Xt+aRoPHPw== From: Sasha Levin To: stable@vger.kernel.org Cc: Chengfeng Ye , Pablo Neira Ayuso , Sasha Levin Subject: [PATCH 6.1.y 2/2] netfilter: cttimeout: prevent UAF during module unload Date: Wed, 16 Sep 2026 20:26:03 -0400 Message-ID: <20260917002603.3379907-2-sashal@kernel.org> X-Mailer: git-send-email 2.53.0 In-Reply-To: <20260917002603.3379907-1-sashal@kernel.org> References: <2026091644-churn-refurbish-6d54@gregkh> <20260917002603.3379907-1-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 eb4d4a3be922f..6067e99830e40 100644 --- a/net/netfilter/nfnetlink_cttimeout.c +++ b/net/netfilter/nfnetlink_cttimeout.c @@ -660,9 +660,9 @@ 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