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From:   Greg Kroah-Hartman <gregkh@linuxfoundation.org>
To:     linux-kernel@vger.kernel.org
Cc:     Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
        stable@vger.kernel.org, Johan Hovold <johan@kernel.org>
Subject: [PATCH 4.4 41/79] USB: adutux: fix use-after-free on release
Date:   Wed, 16 Oct 2019 14:50:16 -0700
Message-Id: <20191016214803.880671748@linuxfoundation.org>
In-Reply-To: <20191016214729.758892904@linuxfoundation.org>
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From: Johan Hovold <johan@kernel.org>

commit 123a0f125fa3d2104043697baa62899d9e549272 upstream.

The driver was accessing its struct usb_device in its release()
callback without holding a reference. This would lead to a
use-after-free whenever the device was disconnected while the character
device was still open.

Fixes: 66d4bc30d128 ("USB: adutux: remove custom debug macro")
Cc: stable <stable@vger.kernel.org>     # 3.12
Signed-off-by: Johan Hovold <johan@kernel.org>
Link: https://lore.kernel.org/r/20191009153848.8664-2-johan@kernel.org
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

---
 drivers/usb/misc/adutux.c |    3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

--- a/drivers/usb/misc/adutux.c
+++ b/drivers/usb/misc/adutux.c
@@ -152,6 +152,7 @@ static void adu_delete(struct adu_device
 	kfree(dev->read_buffer_secondary);
 	kfree(dev->interrupt_in_buffer);
 	kfree(dev->interrupt_out_buffer);
+	usb_put_dev(dev->udev);
 	kfree(dev);
 }
 
@@ -681,7 +682,7 @@ static int adu_probe(struct usb_interfac
 
 	mutex_init(&dev->mtx);
 	spin_lock_init(&dev->buflock);
-	dev->udev = udev;
+	dev->udev = usb_get_dev(udev);
 	init_waitqueue_head(&dev->read_wait);
 	init_waitqueue_head(&dev->write_wait);