Commit 44efc269 authored Sep 25, 2019 by Johan Hovold Committed by Greg Kroah-Hartman Oct 04, 2019

USB: adutux: fix use-after-free on disconnect



The driver was clearing its struct usb_device pointer, which it used as
an inverted disconnected flag, before deregistering the character device
and without serialising against racing release().

This could lead to a use-after-free if a racing release() callback
observes the cleared pointer and frees the driver data before
disconnect() is finished with it.

This could also lead to NULL-pointer dereferences in a racing open().

Fixes: f08812d5 ("USB: FIx locks and urb->status in adutux (updated)")
Cc: stable <stable@vger.kernel.org>     # 2.6.24
Reported-by:  <syzbot+0243cb250a51eeefb8cc@syzkaller.appspotmail.com>
Tested-by:  <syzbot+0243cb250a51eeefb8cc@syzkaller.appspotmail.com>
Signed-off-by: Johan Hovold <johan@kernel.org>
Link: https://lore.kernel.org/r/20190925092913.8608-1-johan@kernel.org


Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

parent 98161443

drivers/usb/misc/adutux.c

+4 −3

Original line number	Diff line number	Diff line
		@@ -762,14 +762,15 @@ static void adu_disconnect(struct usb_interface *interface)

		dev = usb_get_intfdata(interface);

		mutex_lock(&dev->mtx); /* not interruptible */
		dev->udev = NULL; /* poison */
		usb_deregister_dev(interface, &adu_class);
		mutex_unlock(&dev->mtx);

		mutex_lock(&adutux_mutex);
		usb_set_intfdata(interface, NULL);

		mutex_lock(&dev->mtx); /* not interruptible */
		dev->udev = NULL; /* poison */
		mutex_unlock(&dev->mtx);

		/* if the device is not opened, then we clean up right now */
		if (!dev->open_count)
		adu_delete(dev);

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