From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id E4BB5C433F5 for ; Tue, 1 Mar 2022 07:05:52 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S232218AbiCAHGb (ORCPT ); Tue, 1 Mar 2022 02:06:31 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:33662 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229928AbiCAHGa (ORCPT ); Tue, 1 Mar 2022 02:06:30 -0500 Received: from szxga08-in.huawei.com (szxga08-in.huawei.com [45.249.212.255]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 57C4A69CC1; Mon, 28 Feb 2022 23:05:49 -0800 (PST) Received: from canpemm500010.china.huawei.com (unknown [172.30.72.53]) by szxga08-in.huawei.com (SkyGuard) with ESMTP id 4K77Sh6dnWz1GByg; Tue, 1 Mar 2022 15:01:08 +0800 (CST) Received: from [10.174.177.215] (10.174.177.215) by canpemm500010.china.huawei.com (7.192.105.118) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_128_GCM_SHA256) id 15.1.2308.21; Tue, 1 Mar 2022 15:05:46 +0800 Subject: Re: [PATCH bpf-next 2/4] bpf, sockmap: Fix memleak in tcp_bpf_sendmsg while sk msg is full To: John Fastabend , , , , , CC: , , , , , , , , , , References: <20220225014929.942444-1-wangyufen@huawei.com> <20220225014929.942444-3-wangyufen@huawei.com> <621d9aed541f_8c47920864@john.notmuch> From: wangyufen Message-ID: <5eb1bdf2-8f2c-2599-9961-2aace2e8baa6@huawei.com> Date: Tue, 1 Mar 2022 15:05:45 +0800 User-Agent: Mozilla/5.0 (Windows NT 10.0; Win64; x64; rv:78.0) Gecko/20100101 Thunderbird/78.4.0 MIME-Version: 1.0 In-Reply-To: <621d9aed541f_8c47920864@john.notmuch> Content-Type: text/plain; charset="utf-8"; format=flowed Content-Transfer-Encoding: 8bit X-Originating-IP: [10.174.177.215] X-ClientProxiedBy: dggems703-chm.china.huawei.com (10.3.19.180) To canpemm500010.china.huawei.com (7.192.105.118) X-CFilter-Loop: Reflected Precedence: bulk List-ID: X-Mailing-List: netdev@vger.kernel.org 在 2022/3/1 12:02, John Fastabend 写道: > Wang Yufen wrote: >> If tcp_bpf_sendmsg() is running while sk msg is full, sk_msg_alloc() >> returns -ENOSPC, tcp_bpf_sendmsg() goto wait for memory. If partial memory >> has been alloced by sk_msg_alloc(), that is, msg_tx->sg.size is greater >> than osize after sk_msg_alloc(), memleak occurs. To fix we use >> sk_msg_trim() to release the allocated memory, then goto wait for memory. > Small nit, "sk_msg_alloc() returns -ENOSPC" should be something like, "when > sk_msg_alloc() returns -ENOMEM error,..." That error path is from ENOMEM not > the ENOSPC. Thanks, I will fix in v2. > > But nice find thanks! I think we might have seen this in a couple cases on > our side as well. > >> This issue can cause the following info: >> WARNING: CPU: 3 PID: 7950 at net/core/stream.c:208 sk_stream_kill_queues+0xd4/0x1a0 >> Call Trace: >> >> inet_csk_destroy_sock+0x55/0x110 >> __tcp_close+0x279/0x470 >> tcp_close+0x1f/0x60 >> inet_release+0x3f/0x80 >> __sock_release+0x3d/0xb0 >> sock_close+0x11/0x20 >> __fput+0x92/0x250 >> task_work_run+0x6a/0xa0 >> do_exit+0x33b/0xb60 >> do_group_exit+0x2f/0xa0 >> get_signal+0xb6/0x950 >> arch_do_signal_or_restart+0xac/0x2a0 >> exit_to_user_mode_prepare+0xa9/0x200 >> syscall_exit_to_user_mode+0x12/0x30 >> do_syscall_64+0x46/0x80 >> entry_SYSCALL_64_after_hwframe+0x44/0xae >> >> >> WARNING: CPU: 3 PID: 2094 at net/ipv4/af_inet.c:155 inet_sock_destruct+0x13c/0x260 >> Call Trace: >> >> __sk_destruct+0x24/0x1f0 >> sk_psock_destroy+0x19b/0x1c0 >> process_one_work+0x1b3/0x3c0 >> kthread+0xe6/0x110 >> ret_from_fork+0x22/0x30 >> >> >> Fixes: 604326b41a6f ("bpf, sockmap: convert to generic sk_msg interface") >> Signed-off-by: Wang Yufen >> --- >> net/ipv4/tcp_bpf.c | 4 +++- >> 1 file changed, 3 insertions(+), 1 deletion(-) >> >> diff --git a/net/ipv4/tcp_bpf.c b/net/ipv4/tcp_bpf.c >> index 9b9b02052fd3..ac9f491cc139 100644 >> --- a/net/ipv4/tcp_bpf.c >> +++ b/net/ipv4/tcp_bpf.c >> @@ -421,8 +421,10 @@ static int tcp_bpf_sendmsg(struct sock *sk, struct msghdr *msg, size_t size) >> osize = msg_tx->sg.size; >> err = sk_msg_alloc(sk, msg_tx, msg_tx->sg.size + copy, msg_tx->sg.end - 1); >> if (err) { >> - if (err != -ENOSPC) >> + if (err != -ENOSPC) { >> + sk_msg_trim(sk, msg_tx, osize); >> goto wait_for_memory; >> + } >> enospc = true; >> copy = msg_tx->sg.size - osize; >> } >> -- >> 2.25.1 >> > Acked-by: John Fastabend > .