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From:   Greg Kroah-Hartman <gregkh@linuxfoundation.org>
To:     linux-kernel@vger.kernel.org
Cc:     Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
        stable@vger.kernel.org, Wang Yufen <wangyufen@huawei.com>,
        Daniel Borkmann <daniel@iogearbox.net>,
        John Fastabend <john.fastabend@gmail.com>,
        Sasha Levin <sashal@kernel.org>
Subject: [PATCH 5.16 0601/1017] bpf, sockmap: Fix more uncharged while msg has more_data
Date:   Tue,  5 Apr 2022 09:25:14 +0200
Message-Id: <20220405070412.118002939@linuxfoundation.org>
In-Reply-To: <20220405070354.155796697@linuxfoundation.org>
References: <20220405070354.155796697@linuxfoundation.org>
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From: Wang Yufen <wangyufen@huawei.com>

[ 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@huawei.com>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Acked-by: John Fastabend <john.fastabend@gmail.com>
Link: https://lore.kernel.org/bpf/20220304081145.2037182-4-wangyufen@huawei.com
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
 net/ipv4/tcp_bpf.c | 7 +++++--
 1 file changed, 5 insertions(+), 2 deletions(-)

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;
 }
-- 
2.34.1