[PATCH AUTOSEL 4.20 064/304] media: video-i2c: avoid accessing released memory area when removing driver

Sasha Levin
2019-01-28T15:46:09Z

From: Akinobu Mita <akinobu.mita@gmail.com>

[ 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: 5cebaac60974 ("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>
---
drivers/media/i2c/video-i2c.c | 11 ++++++-----
1 file changed, 6 insertions(+), 5 deletions(-)

diff --git a/drivers/media/i2c/video-i2c.c b/drivers/media/i2c/video-i2c.c
index 4d49af86c15e..ec0758dca2fc 100644
--- a/drivers/media/i2c/video-i2c.c
+++ b/drivers/media/i2c/video-i2c.c
@@ -510,7 +510,12 @@ static const struct v4l2_ioctl_ops video_i2c_ioctl_ops = {

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

video_unregister_device(&data->vdev);
- v4l2_device_unregister(&data->v4l2_dev);
-
- mutex_destroy(&data->lock);
- mutex_destroy(&data->queue_lock);

return 0;
}
--
2.19.1