[PATCH 3.16 034/157] USB: serial: mos7720: fix mos_parport refcount imbalance on error path

[Ben Hutchings]

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

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

From: Lin Yi <teroincn@xxxxxxx>

commit 2908b076f5198d231de62713cb2b633a3a4b95ac upstream.

The write_parport_reg_nonblock() helper takes a reference to the struct
mos_parport, but failed to release it in a couple of error paths after
allocation failures, leading to a memory leak.

Johan said that move the kref_get() and mos_parport assignment to the
end of urbtrack initialisation is a better way, so move it. and
mos_parport do not used until urbtrack initialisation.

Signed-off-by: Lin Yi <teroincn@xxxxxxx>
Fixes: b69578df7e98 ("USB: usbserial: mos7720: add support for parallel port on moschip 7715")
Signed-off-by: Johan Hovold <johan@xxxxxxxxxx>
Signed-off-by: Ben Hutchings <ben@xxxxxxxxxxxxxxx>
---
 drivers/usb/serial/mos7720.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

--- a/drivers/usb/serial/mos7720.c
+++ b/drivers/usb/serial/mos7720.c
@@ -362,8 +362,6 @@ static int write_parport_reg_nonblock(st
 	if (!urbtrack)
 		return -ENOMEM;
 
-	kref_get(&mos_parport->ref_count);
-	urbtrack->mos_parport = mos_parport;
 	urbtrack->urb = usb_alloc_urb(0, GFP_ATOMIC);
 	if (!urbtrack->urb) {
 		kfree(urbtrack);
@@ -384,6 +382,8 @@ static int write_parport_reg_nonblock(st
 			     usb_sndctrlpipe(usbdev, 0),
 			     (unsigned char *)urbtrack->setup,
 			     NULL, 0, async_complete, urbtrack);
+	kref_get(&mos_parport->ref_count);
+	urbtrack->mos_parport = mos_parport;
 	kref_init(&urbtrack->ref_count);
 	INIT_LIST_HEAD(&urbtrack->urblist_entry);