Commit 580d8b2f authored Oct 20, 2018 by Akinobu Mita Committed by Greg Kroah-Hartman Feb 12, 2019

media: video-i2c: avoid accessing released memory area when removing driver



[ Upstream commit c764da98a600a4b068d25c77164f092f159cecec ]

The video device release() callback for video-i2c driver frees the whole
struct video_i2c_data.  If there is no user left for the video device
when video_unregister_device() is called, the release callback is executed.

However, in video_i2c_remove() some fields (v4l2_dev, lock, and queue_lock)
in struct video_i2c_data are still accessed after video_unregister_device()
is called.

This fixes the use after free by moving the code from video_i2c_remove()
to the release() callback.

Fixes: 5cebaac6 ("media: video-i2c: add video-i2c driver")

Reviewed-by: Matt Ranostay <matt.ranostay@konsulko.com>
Signed-off-by: Akinobu Mita <akinobu.mita@gmail.com>
Acked-by: Sakari Ailus <sakari.ailus@linux.intel.com>
Signed-off-by: Hans Verkuil <hverkuil@xs4all.nl>
Signed-off-by: Mauro Carvalho Chehab <mchehab+samsung@kernel.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>

parent da77b546

drivers/media/i2c/video-i2c.c

+6 −5

Original line number	Original line	Diff line number	Diff line
	@@ -510,7 +510,12 @@ static const struct v4l2_ioctl_ops video_i2c_ioctl_ops = {

	static void video_i2c_release(struct video_device *vdev)		static void video_i2c_release(struct video_device *vdev)
	{		{
	kfree(video_get_drvdata(vdev));		struct video_i2c_data *data = video_get_drvdata(vdev);

			v4l2_device_unregister(&data->v4l2_dev);
			mutex_destroy(&data->lock);
			mutex_destroy(&data->queue_lock);
			kfree(data);
	}		}

	static int video_i2c_probe(struct i2c_client *client,		static int video_i2c_probe(struct i2c_client *client,
	@@ -608,10 +613,6 @@ static int video_i2c_remove(struct i2c_client *client)
	struct video_i2c_data *data = i2c_get_clientdata(client);		struct video_i2c_data *data = i2c_get_clientdata(client);

	video_unregister_device(&data->vdev);		video_unregister_device(&data->vdev);
	v4l2_device_unregister(&data->v4l2_dev);

	mutex_destroy(&data->lock);
	mutex_destroy(&data->queue_lock);

	return 0;		return 0;
	}		}