usbip: fix vudc to check for stream socket

Fix usbip_sockfd_store() to validate the passed in file descriptor is
a stream socket. If the file descriptor passed was a SOCK_DGRAM socket,
sock_recvmsg() can't detect end of stream.

Cc: stable@vger.kernel.org
Suggested-by: Tetsuo Handa <penguin-kernel@I-love.SAKURA.ne.jp>
Signed-off-by: Shuah Khan <skhan@linuxfoundation.org>
Link: https://lore.kernel.org/r/387a670316002324113ac7ea1e8b53f4085d0c95.1615171203.git.skhan@linuxfoundation.org
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

drivers/usb/usbip/vudc_sysfs.c

@@ -138,6 +138,13 @@ static ssize_t usbip_sockfd_store(struct device *dev, struct device_attribute *a
 			goto unlock_ud;
 		}
 
+		if (socket->type != SOCK_STREAM) {
+			dev_err(dev, "Expecting SOCK_STREAM - found %d",
+				socket->type);
+			ret = -EINVAL;
+			goto sock_err;
+		}
+
 		udc->ud.tcp_socket = socket;
 
 		spin_unlock_irq(&udc->ud.lock);
@@ -177,6 +184,8 @@ static ssize_t usbip_sockfd_store(struct device *dev, struct device_attribute *a
 
 	return count;
 
+sock_err:
+	sockfd_put(socket);
 unlock_ud:
 	spin_unlock_irq(&udc->ud.lock);
 unlock: