tcp: Reset bytes_acked and bytes_received when disconnecting

BugLink: https://bugs.launchpad.net/bugs/1840081

[ Upstream commit e858faf5 ]

If an app is playing tricks to reuse a socket via tcp_disconnect(),
bytes_acked/received needs to be reset to 0. Otherwise tcp_info will
report the sum of the current and the old connection..

Cc: Eric Dumazet <edumazet@google.com>
Fixes: 0df48c26 ("tcp: add tcpi_bytes_acked to tcp_info")
Fixes: bdd1f9ed ("tcp: add tcpi_bytes_received to tcp_info")
Signed-off-by: Christoph Paasch <cpaasch@apple.com>
Signed-off-by: Eric Dumazet <edumazet@google.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: Connor Kuehl <connor.kuehl@canonical.com>
Signed-off-by: Kleber Sacilotto de Souza <kleber.souza@canonical.com>

net/ipv4/tcp.c

@@ -2272,6 +2272,8 @@ int tcp_disconnect(struct sock *sk, int flags)
 	dst_release(sk->sk_rx_dst);
 	sk->sk_rx_dst = NULL;
 	tcp_saved_syn_free(tp);
+	tp->bytes_acked = 0;
+	tp->bytes_received = 0;
 
 	WARN_ON(inet->inet_num && !icsk->icsk_bind_hash);