crypto/tls: fix deadlock when Read and Close called concurrently

The existing implementation of TLS connection has a deadlock. It occurs
when client connects to TLS server and doesn't send data for
handshake, so server calls Close on this connection. This is because
server reads data under locked mutex, while Close method tries to
lock the same mutex.

Fixes #23518

Change-Id: I4fb0a2a770f3d911036bfd9a7da7cc41c1b27e19
Reviewed-on: https://go-review.googlesource.com/90155
Run-TryBot: Brad Fitzpatrick <bradfitz@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Filippo Valsorda <filippo@golang.org>

handshake_client_test.go

@@ -1617,3 +1617,22 @@ RwBA9Xk1KBNF
 		t.Error("A RSA-PSS certificate was parsed like a PKCS1 one, and it will be mistakenly used with rsa_pss_rsae_xxx signature algorithms")
 	}
 }
+
+func TestCloseClientConnectionOnIdleServer(t *testing.T) {
+	clientConn, serverConn := net.Pipe()
+	client := Client(clientConn, testConfig.Clone())
+	go func() {
+		var b [1]byte
+		serverConn.Read(b[:])
+		client.Close()
+	}()
+	client.SetWriteDeadline(time.Now().Add(time.Second))
+	err := client.Handshake()
+	if err != nil {
+		if !strings.Contains(err.Error(), "read/write on closed pipe") {
+			t.Errorf("Error expected containing 'read/write on closed pipe' but got '%s'", err.Error())
+		}
+	} else {
+		t.Errorf("Error expected, but no error returned")
+	}
+}