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=1793782963; b=w0cf8j6zXeD44MkfQtv9CLdrmr3l5kfDevGLZg1UBjotbDkeH5ABL4cMxj/Nl7A/1+uB h/EUaS76+fdi1Ty20OH4LPqKc19rMWeHzlT69nLETNos4ujDc3eksUfd3+svjTj055iWM b5iw1Q5m4R7HKCm0XWvEGjrXB3T0Mv2t5gXyzRUEcb+G/7Ws6CbY/fpHwGjPvVEY+27Cw bCYdalB7T3T/67MZ7pWWF6ds2ogxwwCKnU/ucMQTKQnVynXJTucOg7FZVbHdL++YHV46q JmacAy5uczK6HmQ3git3dvE/0T9ixtON941RSnZGYLejy2dMoUwSTTXUb551rryS9sA== ARC-Message-Signature: i=1; d=subspace.kernel.org; s=arc20261015; a=rsa-sha256; c=relaxed/relaxed; t=1793782963; 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=WEbpxApkfSCt+xdDTHFTYA1rEYHGr1aJ5ATUQY1W/mBVUsTPdTy2i2Oy8gCmbB5G7WDl OMAG0WQ+9l1jx2NZClqqjJY0Hd0QuwkTnChj/YpUEaCdAWmqFfucDPbHxJbxKqmsnjIBB TrFFSKqvmRjRCBmbnwIZvAFh0pOfIpkEOYicyU4xHckTNmWW5A7sCKo6Xb/Oodp4WEBib t86gUK3ctzYTHZMNNo9M1AqdPLMCrqJNWroW+NhCPEthZ1xml2qzTDrC3ksZqfKljAxFl lDt2WbeGAQsUdQ/7AHyeoSCTvNi+BEOZKJNyp+PG8aC7eSfHlWvaJ0uvhihaOz5SMyw== 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=VPxKba55; 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 ECC89606A32E; Wed, 4 Nov 2026 09:02:42 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.4.2 smtp.subspace.kernel.org ECC89606A32E 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=VPxKba55 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=netfilter.org; s=2025; t=1793782956; bh=tGglPb/JNoW60gebCDiplQzdX4hezWP6upe63JPqTbE=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=VPxKba55essc2y2lR8KjLxoO7R77kOPPS+cDj5xgeopFWxusWcKVzUbD6PXwQ5abA ookmDCTz7+CsKkKKaDqeGIHeYxMOsChSCGqGF9HLIx4G9GWsH6VWooWSdG5ncDDBum 44dzlVQJ92aQoT0kklTPOC217DzhMSwy5hwHDJcAYV5JiJw+A78bj8DGtyTTijZnAM /NU4GCTLJpoNvFGvXrQ1vXq+woYfetSwXrQdobVm2kQsNiAIdtZNPNxcHcRhuX+569 kVpBNFZ8mUVoMHaIy+VWUZNuiwVUlO4BGUd5tpDrYYbZOdEkEcv9SLZb6GYoOrj5ht l92b6E54CYM2Q== Received: from localhost.localdomain (mail-agni [217.70.190.124]) by mail.netfilter.org (Postfix) with ESMTPSA id 959B360085; Wed, 4 Nov 2026 10:02:35 +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 02/13] ipvs: Defer application parent freeing until after RCU readers Date: Wed, 4 Nov 2026 10:02:13 +0100 Message-ID: <20261104090224.750548-3-pablo@netfilter.org> X-Mailer: git-send-email 2.47.3 In-Reply-To: <20261104090224.750548-1-pablo@netfilter.org> References: <20261104090224.750548-1-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