linux-kernel - [BUG] au0828: dev->lock in au0828_usb

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Date:	Thu, 23 Jun 2016 00:11:04 +0100
From:	Alexey Khoroshilov <khoroshilov@...ras.ru>
To:	Shuah Khan <shuahkh@....samsung.com>,
	Mauro Carvalho Chehab <mchehab@....samsung.com>
Cc:	Alexey Khoroshilov <khoroshilov@...ras.ru>,
	linux-media@...r.kernel.org, linux-kernel@...r.kernel.org,
	ldv-project@...uxtesting.org
Subject: [BUG] au0828: dev->lock in au0828_usb_probe()

It is not quite clear what does mutex_lock(&dev->lock) defend against.

If there is a chance that some other code can try to lock the mutex during probe(),
then 
  mutex_unlock(&dev->lock);
  kfree(dev);
looks suspicious, because when that code get control form mutex_lock(dev->lock)
the dev could be already freed.

Otherwise, dev->lock should not be acquired so early.

Another problem is that on the path going via goto done
there is no mutex_unlock(&dev->lock).

Found by Linux Driver Verification project (linuxtesting.org).

--
Alexey Khoroshilov
Linux Verification Center, ISPRAS
web: http://linuxtesting.org