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 <stern@rowland.harvard.edu>
Tested-by: Jean-Denis Girard <jd.girard@sysnux.pf>
CC: stable <stable@kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>

drivers/usb/serial/usb-serial.c

@@ -156,6 +156,7 @@ static void destroy_serial(struct kref *kref)
 	if (serial->minor != SERIAL_TTY_NO_MINOR)
 		return_serial(serial);
 
+	if (serial->attached)
 		serial->type->release(serial);
 
 	/* Now that nothing is using the ports, they can be freed */
@@ -1059,12 +1060,15 @@ int usb_serial_probe(struct usb_interface *interface,
 		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

@@ -150,6 +150,7 @@ struct usb_serial {
 	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;