[PATCH 3.16 164/370] USB: serial: mos7720: fix use-after-free on probe errors

Ben Hutchings
2017-03-10T13:56:32Z

From: Johan Hovold <johan@kernel.org>

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@kernel.org>
Signed-off-by: Ben Hutchings <ben@decadent.org.uk>
---
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
@@ -1946,8 +1946,10 @@ 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 */
@@ -1959,6 +1961,8 @@ static int mos7720_startup(struct usb_se

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 */