Re: [PATCH bpf-next v2 3/4] bpf, sockmap: Fix more uncharged while msg has more_data

On Wed, Mar 02, 2022 at 10:27:54AM +0800, 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.

It looks like bpf_exec_tx_verdict() has the same issue.