Re: [PATCH 2/8] vfio/mdev: Avoid release parent reference during error path

[Maxim Levitsky]

On Fri, 2019-03-22 at 18:20 -0500, Parav Pandit wrote:
> During mdev parent registration in mdev_register_device(),
> if parent device is duplicate, it releases the reference of existing
> parent device.
> This is incorrect. Existing parent device should not be touched.
> 
> Fixes: 7b96953bc640 ("vfio: Mediated device Core driver")
> Signed-off-by: Parav Pandit <parav@xxxxxxxxxxxx>
> ---
>  drivers/vfio/mdev/mdev_core.c | 1 +
>  1 file changed, 1 insertion(+)
> 
> diff --git a/drivers/vfio/mdev/mdev_core.c b/drivers/vfio/mdev/mdev_core.c
> index 3e5880a..4f213e4d 100644
> --- a/drivers/vfio/mdev/mdev_core.c
> +++ b/drivers/vfio/mdev/mdev_core.c
> @@ -182,6 +182,7 @@ int mdev_register_device(struct device *dev, const struct
> mdev_parent_ops *ops)
>  	/* Check for duplicate */
>  	parent = __find_parent_device(dev);
>  	if (parent) {
> +		parent = NULL;
>  		ret = -EEXIST;
>  		goto add_dev_err;
>  	}

This is also clearly an issue.

Reviewed-by: Maxim Levitsky <mlevitsk@xxxxxxxxxx>

Best regards,
	Maxim Levitsky