From: Johan Hovold Date: Wed, 25 Sep 2019 09:29:12 +0000 (+0200) Subject: USB: adutux: fix use-after-free on disconnect X-Git-Tag: v3.16.79~9 X-Git-Url: http://git.ipfire.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=22cbb8fb12b3b5101260915162ad2b0b56a9284d;p=thirdparty%2Fkernel%2Fstable.git USB: adutux: fix use-after-free on disconnect 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 Link: https://lore.kernel.org/r/20190925092913.8608-1-johan@kernel.org Signed-off-by: Greg Kroah-Hartman Signed-off-by: Ben Hutchings --- diff --git a/drivers/usb/misc/adutux.c b/drivers/usb/misc/adutux.c index f6f7372dd2fb1..065db5f4b62b4 100644 --- a/drivers/usb/misc/adutux.c +++ b/drivers/usb/misc/adutux.c @@ -799,14 +799,15 @@ 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);