Commit 44efc269 authored by Johan Hovold's avatar Johan Hovold Committed by Greg Kroah-Hartman

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: default avatarJohan Hovold <johan@kernel.org>
Link: https://lore.kernel.org/r/20190925092913.8608-1-johan@kernel.orgSigned-off-by: default avatarGreg Kroah-Hartman <gregkh@linuxfoundation.org>
parent 98161443
...@@ -762,14 +762,15 @@ static void adu_disconnect(struct usb_interface *interface) ...@@ -762,14 +762,15 @@ static void adu_disconnect(struct usb_interface *interface)
dev = usb_get_intfdata(interface); dev = usb_get_intfdata(interface);
mutex_lock(&dev->mtx); /* not interruptible */
dev->udev = NULL; /* poison */
usb_deregister_dev(interface, &adu_class); usb_deregister_dev(interface, &adu_class);
mutex_unlock(&dev->mtx);
mutex_lock(&adutux_mutex); mutex_lock(&adutux_mutex);
usb_set_intfdata(interface, NULL); 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 the device is not opened, then we clean up right now */
if (!dev->open_count) if (!dev->open_count)
adu_delete(dev); adu_delete(dev);
......
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