3.16.79-rc1 review patch. If anyone has any objections, please let me know.
------------------
From: Johan Hovold johan@kernel.org
commit 44efc269db7929f6275a1fa927ef082e533ecde0 upstream.
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: f08812d5eb8f ("USB: FIx locks and urb->status in adutux (updated)") 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 Signed-off-by: Ben Hutchings ben@decadent.org.uk --- drivers/usb/misc/adutux.c | 7 ++++--- 1 file changed, 4 insertions(+), 3 deletions(-)
--- a/drivers/usb/misc/adutux.c +++ b/drivers/usb/misc/adutux.c @@ -799,14 +799,15 @@ static void adu_disconnect(struct usb_in
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);