On 05/03/2016 05:06 PM, Shuah Khan wrote:
> On 05/02/2016 04:16 AM, Lars-Peter Clausen wrote:
>> On 04/30/2016 12:37 AM, Shuah Khan wrote:
>> [...]
>>> diff --git a/include/media/media-devnode.h b/include/media/media-devnode.h
>>> index 5bb3b0e..ce9b051 100644
>>> --- a/include/media/media-devnode.h
>>> +++ b/include/media/media-devnode.h
>>> @@ -72,6 +72,7 @@ struct media_file_operations {
>>> * @fops: pointer to struct &media_file_operations with media device ops
>>> * @dev: struct device pointer for the media controller device
>>> * @cdev: struct cdev pointer character device
>>> + * @kobj: struct kobject
>>> * @parent: parent device
>>> * @minor: device node minor number
>>> * @flags: flags, combination of the MEDIA_FLAG_* constants
>>> @@ -91,6 +92,7 @@ struct media_devnode {
>>> /* sysfs */
>>> struct device dev; /* media device */
>>> struct cdev cdev; /* character device */
>>> + struct kobject kobj; /* set as cdev parent kobj */
>>
>> As said during the previous review, the struct device should be used for
>> reference counting. Otherwise a use-after-free can still occur since you now
>> have two reference counted data structures with independent counters in the
>> same structure. For one of them the counter goes to zero before the other
>> and then you have the use-after-free.
>>
>
> struct device is embedded in the media_devnode and media_devnode
> will not be released until cdev releases the kobject since it is
> set as cdeev kobj.parent. I am not seeing any use-fater-free with
> this scheme.
There might still be a reference to the struct device at that point, so if
you free the media_devnode there is a use-after-free.
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