Patch "bpf, sockmap: Fix more uncharged while msg has more_data" has been added to the 5.15-stable tree

[Sasha Levin <sashal@xxxxxxxxxx>]

This is a note to let you know that I've just added the patch titled

    bpf, sockmap: Fix more uncharged while msg has more_data

to the 5.15-stable tree which can be found at:
    http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary

The filename of the patch is:
     bpf-sockmap-fix-more-uncharged-while-msg-has-more_da.patch
and it can be found in the queue-5.15 subdirectory.

If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.



commit 0a0c70e03780d59c7d0256757e7e0bd6bf5720d9
Author: Wang Yufen <wangyufen@xxxxxxxxxx>
Date:   Fri Mar 4 16:11:44 2022 +0800

    bpf, sockmap: Fix more uncharged while msg has more_data
    
    [ Upstream commit 84472b436e760ba439e1969a9e3c5ae7c86de39d ]
    
    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@xxxxxxxxxx>
    Signed-off-by: Daniel Borkmann <daniel@xxxxxxxxxxxxx>
    Acked-by: John Fastabend <john.fastabend@xxxxxxxxx>
    Link: https://lore.kernel.org/bpf/20220304081145.2037182-4-wangyufen@xxxxxxxxxx
    Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx>

diff --git a/net/ipv4/tcp_bpf.c b/net/ipv4/tcp_bpf.c
index 9b9b02052fd3..304800c60427 100644
--- a/net/ipv4/tcp_bpf.c
+++ b/net/ipv4/tcp_bpf.c
@@ -335,7 +335,7 @@ static int tcp_bpf_send_verdict(struct sock *sk, struct sk_psock *psock,
 			cork = true;
 			psock->cork = NULL;
 		}
-		sk_msg_return(sk, msg, tosend);
+		sk_msg_return(sk, msg, msg->sg.size);
 		release_sock(sk);
 
 		ret = tcp_bpf_sendmsg_redir(sk_redir, msg, tosend, flags);
@@ -375,8 +375,11 @@ static int tcp_bpf_send_verdict(struct sock *sk, struct sk_psock *psock,
 		}
 		if (msg &&
 		    msg->sg.data[msg->sg.start].page_link &&
-		    msg->sg.data[msg->sg.start].length)
+		    msg->sg.data[msg->sg.start].length) {
+			if (eval == __SK_REDIRECT)
+				sk_mem_charge(sk, msg->sg.size);
 			goto more_data;
+		}
 	}
 	return ret;
 }