[PATCH 4.19 39/81] USB: legousbtower: fix use-after-free on release

From: Greg Kroah-Hartman
Date: Wed Oct 16 2019 - 17:58:37 EST


From: Johan Hovold <johan@xxxxxxxxxx>

commit 726b55d0e22ca72c69c947af87785c830289ddbc upstream.

The driver was accessing its struct usb_device in its release()
callback without holding a reference. This would lead to a
use-after-free whenever the device was disconnected while the character
device was still open.

Fixes: fef526cae700 ("USB: legousbtower: remove custom debug macro")
Cc: stable <stable@xxxxxxxxxxxxxxx> # 3.12
Signed-off-by: Johan Hovold <johan@xxxxxxxxxx>
Link: https://lore.kernel.org/r/20191009153848.8664-5-johan@xxxxxxxxxx
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>

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

--- a/drivers/usb/misc/legousbtower.c
+++ b/drivers/usb/misc/legousbtower.c
@@ -296,6 +296,7 @@ static inline void tower_delete (struct
kfree (dev->read_buffer);
kfree (dev->interrupt_in_buffer);
kfree (dev->interrupt_out_buffer);
+ usb_put_dev(dev->udev);
kfree (dev);
}

@@ -810,7 +811,7 @@ static int tower_probe (struct usb_inter

mutex_init(&dev->lock);

- dev->udev = udev;
+ dev->udev = usb_get_dev(udev);
dev->open_count = 0;
dev->disconnected = 0;