[PATCH 3.2 075/199] USB: serial: mos7720: fix use-after-free on probe errors

[Ben Hutchings]

3.2.87-rc1 review patch.  If anyone has any objections, please let me know.

------------------

From: Johan Hovold <johan@xxxxxxxxxx>

commit 91a1ff4d53c5184d383d0baeeaeab6f9736f2ff3 upstream.

The interrupt URB was submitted on probe but never stopped on probe
errors. This can lead to use-after-free issues in the completion
handler when accessing the freed usb-serial struct:

Unable to handle kernel paging request at virtual address 6b6b6be7
...
[<bf052e70>] (mos7715_interrupt_callback [mos7720]) from [<c052a894>] (__usb_hcd_giveback_urb+0x80/0x140)
[<c052a894>] (__usb_hcd_giveback_urb) from [<c052a9a4>] (usb_hcd_giveback_urb+0x50/0x138)
[<c052a9a4>] (usb_hcd_giveback_urb) from [<c0550684>] (musb_giveback+0xc8/0x1cc)

Fixes: b69578df7e98 ("USB: usbserial: mos7720: add support for parallel
port on moschip 7715")
Signed-off-by: Johan Hovold <johan@xxxxxxxxxx>
[bwh: Backported to 3.2: adjust context]
Signed-off-by: Ben Hutchings <ben@xxxxxxxxxxxxxxx>
---
 drivers/usb/serial/mos7720.c | 6 +++++-
 1 file changed, 5 insertions(+), 1 deletion(-)

--- a/drivers/usb/serial/mos7720.c
+++ b/drivers/usb/serial/mos7720.c
@@ -2147,8 +2147,10 @@ static int mos7720_startup(struct usb_se
 #ifdef CONFIG_USB_SERIAL_MOS7715_PARPORT
 	if (product == MOSCHIP_DEVICE_ID_7715) {
 		ret_val = mos7715_parport_init(serial);
-		if (ret_val < 0)
+		if (ret_val < 0) {
+			usb_kill_urb(serial->port[0]->interrupt_in_urb);
 			return ret_val;
+		}
 	}
 #endif
 	/* LSR For Port 1 */
@@ -2162,6 +2164,8 @@ static void mos7720_release(struct usb_s
 {
 	int i;
 
+	usb_kill_urb(serial->port[0]->interrupt_in_urb);
+
 #ifdef CONFIG_USB_SERIAL_MOS7715_PARPORT
 	/* close the parallel port */