[PATCH 3.12 104/235] USB: serial: mos7720: fix use-after-free on probe errors

[Jiri Slaby]

From: Johan Hovold <johan@xxxxxxxxxx>

3.12-stable review patch.  If anyone has any objections, please let me know.

===============

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>
Signed-off-by: Jiri Slaby <jslaby@xxxxxxx>
---
 drivers/usb/serial/mos7720.c | 6 +++++-
 1 file changed, 5 insertions(+), 1 deletion(-)

diff --git a/drivers/usb/serial/mos7720.c b/drivers/usb/serial/mos7720.c
index b0695b667fb2..67be5d26d7a3 100644
--- a/drivers/usb/serial/mos7720.c
+++ b/drivers/usb/serial/mos7720.c
@@ -1961,8 +1961,10 @@ static int mos7720_startup(struct usb_serial *serial)
 #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 */
@@ -1974,6 +1976,8 @@ static int mos7720_startup(struct usb_serial *serial)
 
 static void mos7720_release(struct usb_serial *serial)
 {
+	usb_kill_urb(serial->port[0]->interrupt_in_urb);
+
 #ifdef CONFIG_USB_SERIAL_MOS7715_PARPORT
 	/* close the parallel port */
 
-- 
2.11.0