This is a note to let you know that I've just added the patch titled

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

to my usb git tree which can be found at git://git.kernel.org/pub/scm/linux/kernel/git/gregkh/usb.git in the usb-linus branch.

The patch will show up in the next release of the linux-next tree (usually sometime within the next 24 hours during the week.)

The patch will hopefully also be merged in Linus's tree for the next -rc kernel release.

If you have any questions about this process, please let me know.

From 44efc269db7929f6275a1fa927ef082e533ecde0 Mon Sep 17 00:00:00 2001

From: Johan Hovold johan@kernel.org Date: Wed, 25 Sep 2019 11:29:12 +0200 Subject: 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: f08812d5eb8f ("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 --- drivers/usb/misc/adutux.c | 7 ++++--- 1 file changed, 4 insertions(+), 3 deletions(-)

diff --git a/drivers/usb/misc/adutux.c b/drivers/usb/misc/adutux.c index 344d523b0502..bcc138990e2f 100644 --- a/drivers/usb/misc/adutux.c +++ b/drivers/usb/misc/adutux.c @@ -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);