[PATCH 4.9 52/92] USB: iowarrior: fix use-after-free on release

[Greg Kroah-Hartman]

From: Johan Hovold <johan@xxxxxxxxxx>

commit 80cd5479b525093a56ef768553045741af61b250 upstream.

The driver was accessing its struct usb_interface from its release()
callback without holding a reference. This would lead to a
use-after-free whenever debugging was enabled and the device was
disconnected while its character device was open.

Fixes: 549e83500b80 ("USB: iowarrior: Convert local dbg macro to dev_dbg")
Cc: stable <stable@xxxxxxxxxxxxxxx>     # 3.16
Signed-off-by: Johan Hovold <johan@xxxxxxxxxx>
Link: https://lore.kernel.org/r/20191009104846.5925-3-johan@xxxxxxxxxx
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>

---
 drivers/usb/misc/iowarrior.c |    3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

--- a/drivers/usb/misc/iowarrior.c
+++ b/drivers/usb/misc/iowarrior.c
@@ -248,6 +248,7 @@ static inline void iowarrior_delete(stru
 	kfree(dev->int_in_buffer);
 	usb_free_urb(dev->int_in_urb);
 	kfree(dev->read_queue);
+	usb_put_intf(dev->interface);
 	kfree(dev);
 }
 
@@ -776,7 +777,7 @@ static int iowarrior_probe(struct usb_in
 	init_waitqueue_head(&dev->write_wait);
 
 	dev->udev = udev;
-	dev->interface = interface;
+	dev->interface = usb_get_intf(interface);
 
 	iface_desc = interface->cur_altsetting;
 	dev->product_id = le16_to_cpu(udev->descriptor.idProduct);