USB: serial: don't call release without attach

This patch (as1295) fixes a recently-added bug in the USB serial core.
If certain kinds of errors occur during probing, the core may call a
serial driver's release method without previously calling the attach
method. This causes some drivers (io_ti in particular) to perform an
invalid memory access.

The patch adds a new flag to keep track of whether or not attach has
been called.

Signed-off-by: Alan Stern <[e-mail]>
Tested-by: Jean-Denis Girard <[e-mail]>
CC: stable <[e-mail]>
Signed-off-by: Greg Kroah-Hartman <[e-mail]>

drivers/usb/serial/usb-serial.c

···
 	if (serial->minor != SERIAL_TTY_NO_MINOR)
 		return_serial(serial);
 
-	serial->type->release(serial);
+	if (serial->attached)
+		serial->type->release(serial);
 
 	/* Now that nothing is using the ports, they can be freed */
 	for (i = 0; i < serial->num_port_pointers; ++i) {
···
 		module_put(type->driver.owner);
 		if (retval < 0)
 			goto probe_error;
+		serial->attached = 1;
 		if (retval > 0) {
 			/* quietly accept this device, but don't bind to a
 			   serial port as it's about to disappear */
 			serial->num_ports = 0;
 			goto exit;
 		}
+	} else {
+		serial->attached = 1;
 	}
 
 	if (get_free_serial(serial, num_ports, &minor) == NULL) {

include/linux/usb/serial.h

···
 	struct usb_interface		*interface;
 	unsigned char			disconnected:1;
 	unsigned char			suspending:1;
+	unsigned char			attached:1;
 	unsigned char			minor;
 	unsigned char			num_ports;
 	unsigned char			num_port_pointers;