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

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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: f08812d5eb ("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>
This commit is contained in:
Johan Hovold 2019-09-25 11:29:12 +02:00 committed by Greg Kroah-Hartman
parent 9816144313
commit 44efc269db
1 changed files with 4 additions and 3 deletions
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7
drivers/usb/misc/adutux.c
View file

@ -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);