netdev - RE: [PATCH bpf-next 3/4] bpf, sockmap: Fix more uncharged while msg has more

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Message-ID: <621d9efbec66f_8c479208eb@john.notmuch>
Date:   Mon, 28 Feb 2022 20:20:11 -0800
From:   John Fastabend <john.fastabend@...il.com>
To:     Wang Yufen <wangyufen@...wei.com>, john.fastabend@...il.com,
        daniel@...earbox.net, jakub@...udflare.com, lmb@...udflare.com,
        davem@...emloft.net, bpf@...r.kernel.org
Cc:     edumazet@...gle.com, yoshfuji@...ux-ipv6.org, dsahern@...nel.org,
        kuba@...nel.org, ast@...nel.org, andrii@...nel.org, kafai@...com,
        songliubraving@...com, yhs@...com, kpsingh@...nel.org,
        netdev@...r.kernel.org, Wang Yufen <wangyufen@...wei.com>
Subject: RE: [PATCH bpf-next 3/4] bpf, sockmap: Fix more uncharged while msg
 has more_data

Wang Yufen wrote:
> In tcp_bpf_send_verdict(), if msg has more data after
> tcp_bpf_sendmsg_redir():
> 
> tcp_bpf_send_verdict()
>  tosend = msg->sg.size  //msg->sg.size = 22220
>  case __SK_REDIRECT:
>   sk_msg_return()  //uncharged msg->sg.size(22220) sk->sk_forward_alloc
>   tcp_bpf_sendmsg_redir() //after tcp_bpf_sendmsg_redir, msg->sg.size=11000
>  goto more_data;
>  tosend = msg->sg.size  //msg->sg.size = 11000
>  case __SK_REDIRECT:
>   sk_msg_return()  //uncharged msg->sg.size(11000) to sk->sk_forward_alloc
> 
> The msg->sg.size(11000) has been uncharged twice, to fix we can charge the
> remaining msg->sg.size before goto more data.
> 
> This issue can cause the following info:
> WARNING: CPU: 0 PID: 9860 at net/core/stream.c:208 sk_stream_kill_queues+0xd4/0x1a0
> Call Trace:
>  <TASK>
>  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
>  ? vfs_write+0x237/0x290
>  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
>  </TASK>
> 
> WARNING: CPU: 0 PID: 2136 at net/ipv4/af_inet.c:155 inet_sock_destruct+0x13c/0x260
> Call Trace:
>  <TASK>
>  __sk_destruct+0x24/0x1f0
>  sk_psock_destroy+0x19b/0x1c0
>  process_one_work+0x1b3/0x3c0
>  worker_thread+0x30/0x350
>  ? process_one_work+0x3c0/0x3c0
>  kthread+0xe6/0x110
>  ? kthread_complete_and_exit+0x20/0x20
>  ret_from_fork+0x22/0x30
>  </TASK>
> 
> Fixes: 604326b41a6f ("bpf, sockmap: convert to generic sk_msg interface")
> Signed-off-by: Wang Yufen <wangyufen@...wei.com>
> ---

LGTM also fixes another charge error when going through the error path with
apply set where it looks like we would have left some bytes charged to the
socket.

Acked-by: John Fastabend <john.fastabend@...il.com>