From mboxrd@z Thu Jan 1 00:00:00 1970 Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.remote-ip=217.70.190.124 ARC-Seal: i=1; d=subspace.kernel.org; s=arc20261015; a=rsa-sha256; cv=none; t=1793714602; b=I9tZ9YcFxpZXgIgM4rHHpGouPHvgJpVq8LOz24dZ7OQ5MWy15HdxSxYthuM5Se0IqabQ 8lhQvEYYlofOfk51WiG/C5qdtL7+C6zowgyJ+m1ZKTukMsCV5PGOIQONXAgYQXRhzrWEh rXzn6kQJmDKZqhssmzNompS3Yic7nnSqt7J9M8YKDYKp3qWc0jK/rco89gF4bPvtRtRRL topYMo3gFLd7YrsZKrcOeuh8qkkP/XxYLd9an9nZ44xCuQXiVBySrQQO8f47qLvE2y0nG jCl6edhKJkKi0Mre1iqeWVybiFP/kJM261BDfbmUTNQIk5bwuUuP8RzFIl10YFKmBPA== ARC-Message-Signature: i=1; d=subspace.kernel.org; s=arc20261015; a=rsa-sha256; c=relaxed/relaxed; t=1793714602; h=DMARC-Filter:DKIM-Signature:Received:From:To:Cc:Subject:Date: Message-ID:X-Mailer:In-Reply-To:References:MIME-Version: Content-Transfer-Encoding:X-Spam-Status:X-Spam-Checker-Version; bh=tGglPb/JNoW60gebCDiplQzdX4hezWP6upe63JPqTbE=; b=B+UrrtcRXplN8/cBl7TaaMOf+4ZebT1zkSmTixzfC3YMggZhncv/+5UtkcGPjEsazdPS 7iGD/OBHH296aShQLRizzS0pQQILcVqeXTZ1G3ezyHGb/BzIB4PYK6MqO9UJTKa6ngx0Z u3Yu9W5Pdt9020I5N7K2Yx5WQHvoxAmY2T2LlhnIkoaFUu3Xvg/fzVgHOxxl8iktzjCet U07b0XqL2jJM0jaXuli6mFi1EHt/enQzpEaEmLYvM1tTTIt27rJUzmWSlfuRFkNq2JRsj s0MzI+7rPdMdtV1y0x72Ps3taGmkKeEECqGGsANcJET2/5YcucgSxXQyWGFYFD3dttA== ARC-Authentication-Results: i=1; smtp.subspace.kernel.org; dmarc=none header.from=netfilter.org; spf=pass smtp.mailfrom=netfilter.org; dkim=pass header.d=netfilter.org header.i=@netfilter.org header.a=rsa-sha256 header.s=2025 header.b=upGzGZKQ; arc=none smtp.remote-ip=217.70.190.124 Received: from mail.netfilter.org (mail.netfilter.org [217.70.190.124]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature ECDSA (prime256v1)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 6820F6082BD7; Tue, 3 Nov 2026 14:03:22 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.4.2 smtp.subspace.kernel.org 6820F6082BD7 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, unprotected) header.d=netfilter.org header.i=@netfilter.org header.a=rsa-sha256 header.s=2025 header.b=upGzGZKQ DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=netfilter.org; s=2025; t=1793714600; bh=tGglPb/JNoW60gebCDiplQzdX4hezWP6upe63JPqTbE=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=upGzGZKQWX/PvlXDfBvVqWiTNmg4EWs06fHZDNsrjg4RH2Hsl7da6+afLmBeA4nmI AfDwP+I9Otl23P0EE8iITgsNJyCVuKBMaWus37TwPM8psOrF61pP4jTLY18Xtsvgxi BLBawXGscx6Tq5Oa3nT+VND27shiMKVJhpdgcR/OkXxLMUhPeQZW7Pu+wjpQ1btZg5 LqSSjzhuHMsWXaPqWauh+cgtZAnunswjznQCTRzjEktBT8SyNqhac3f3EMurThtNuI gNojYx3ifVsOBBdoimXhtX39sdXjBeXt0h0Gbo+vNgcegRqcr8uUFBZUnA4lkbVqyj MuTWcVtwLAhbA== Received: from localhost.localdomain (mail-agni [217.70.190.124]) by mail.netfilter.org (Postfix) with ESMTPSA id E237560090; Tue, 3 Nov 2026 15:03:19 +0100 (CET) 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@kernel.org, horms@kernel.org, fw@strlen.de, ja@ssi.bg Subject: [PATCH net 03/15] ipvs: Defer application parent freeing until after RCU readers Date: Tue, 3 Nov 2026 15:02:56 +0100 Message-ID: <20261103140308.591690-5-pablo@netfilter.org> X-Mailer: git-send-email 2.47.3 In-Reply-To: <20261103140308.591690-1-pablo@netfilter.org> References: <20261103140308.591690-1-pablo@netfilter.org> X-Mailing-List: netdev@vger.kernel.org List-Id: List-Post: List-Help: List-Subscribe: List-Unsubscribe: List-Owner: Precedence: list MIME-Version: 1.0 Content-Transfer-Encoding: 8bit From: Chengfeng Ye unregister_ip_vs_app() removes each incarnation from its protocol list and uses call_rcu() to defer freeing it, but frees the parent application immediately. An RCU reader that already found an incarnation can still access the parent through inc->app in ip_vs_app_inc_get(). During FTP helper module unload, the following interleaving is possible: CPU 0 (RCU reader) CPU 1 (module unload) tcp_app_conn_bind() find inc in protocol list unregister_ip_vs_app() ip_vs_app_inc_release(inc) list_del_rcu(&inc->p_list) call_rcu(&inc->rcu_head, ...) kfree(a) ip_vs_app_inc_get(inc) try_module_get(inc->app->module) The helper module is already going away, so try_module_get() would fail, but evaluating its argument first reads the freed parent. The subsequent rcu_barrier() in pernet unregistration cannot protect this earlier free. KASAN reported: BUG: KASAN: slab-use-after-free in ip_vs_app_inc_get+0x7c/0x90 Call Trace: ip_vs_app_inc_get+0x7c/0x90 tcp_app_conn_bind+0x1bc/0x290 ip_vs_conn_new+0x1915/0x20d0 ip_vs_schedule+0x697/0xea0 tcp_conn_schedule+0x489/0x820 ip_vs_in_hook+0x7bf/0x1f40 Allocated by task 88: kmemdup_noprof+0x20/0x50 register_ip_vs_app+0x12d/0x2c0 __ip_vs_ftp_init+0x56/0x160 [ip_vs_ftp] Freed by task 104: kfree+0x131/0x3c0 unregister_ip_vs_app+0x2f4/0x5b0 unregister_pernet_operations+0x232/0x490 unregister_pernet_subsys+0x1c/0x30 __do_sys_delete_module+0x346/0x510 Use kfree_rcu() with the existing rcu_head to keep the parent alive until these readers finish. Successful helper references already prevent normal module unload, and incarnation RCU callbacks do not access the parent. Fixes: 363c97d7435e ("ipvs: convert app locks") Cc: stable@vger.kernel.org Signed-off-by: Chengfeng Ye Acked-by: Julian Anastasov Signed-off-by: Pablo Neira Ayuso --- net/netfilter/ipvs/ip_vs_app.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/net/netfilter/ipvs/ip_vs_app.c b/net/netfilter/ipvs/ip_vs_app.c index 11cbdbaf561d..2c1b47702da2 100644 --- a/net/netfilter/ipvs/ip_vs_app.c +++ b/net/netfilter/ipvs/ip_vs_app.c @@ -242,7 +242,7 @@ void unregister_ip_vs_app(struct netns_ipvs *ipvs, struct ip_vs_app *app) } list_del(&a->a_list); - kfree(a); + kfree_rcu(a, rcu_head); /* decrease the module use count */ ip_vs_use_count_dec(); -- 2.47.3