[PATCH 3.16 053/136] USB: legousbtower: fix use-after-free on release

Ben Hutchings
2019-12-17T00:58:29Z

From: Johan Hovold <johan@kernel.org>

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")
Signed-off-by: Johan Hovold <johan@kernel.org>
Link: https://lore.kernel.org/r/20191009153848.8664-5-johan@kernel.org
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: Ben Hutchings <ben@decadent.org.uk>
---
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
@@ -302,6 +302,7 @@ 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);
}

@@ -820,7 +821,7 @@ 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;