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Subject: Re: [PATCH bpf-next 1/4] bpf, sockmap: Fix memleak in
 sk_psock_queue_msg
To:     Cong Wang <xiyou.wangcong@gmail.com>
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From:   wangyufen <wangyufen@huawei.com>
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在 2022/2/28 3:21, Cong Wang 写道:
> On Fri, Feb 25, 2022 at 09:49:26AM +0800, Wang Yufen wrote:
>> If tcp_bpf_sendmsg is running during a tear down operation we may enqueue
>> data on the ingress msg queue while tear down is trying to free it.
>>
>>   sk1 (redirect sk2)                         sk2
>>   -------------------                      ---------------
>> tcp_bpf_sendmsg()
>>   tcp_bpf_send_verdict()
>>    tcp_bpf_sendmsg_redir()
>>     bpf_tcp_ingress()
>>                                            sock_map_close()
>>                                             lock_sock()
>>      lock_sock() ... blocking
>>                                             sk_psock_stop
>>                                              sk_psock_clear_state(psock, SK_PSOCK_TX_ENABLED);
>>                                             release_sock(sk);
>>      lock_sock()	
>>      sk_mem_charge()
>>      get_page()
>>      sk_psock_queue_msg()
>>       sk_psock_test_state(psock, SK_PSOCK_TX_ENABLED);
>>        drop_sk_msg()
>>      release_sock()
>>
>> While drop_sk_msg(), the msg has charged memory form sk by sk_mem_charge
>> and has sg pages need to put. To fix we use sk_msg_free() and then kfee()
>> msg.
>>
> What about the other code path? That is, sk_psock_skb_ingress_enqueue().
> I don't see skmsg is charged there.

sk_psock_skb_ingress_self() | sk_psock_skb_ingress()
    skb_set_owner_r()
       sk_mem_charge()
    sk_psock_skb_ingress_enqueue()

The other code path skmsg is charged by skb_set_owner_r()->sk_mem_charge()

>
> Thanks.
> .