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

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Date:   Mon, 25 Mar 2019 13:49:36 +0200
From:   Maxim Levitsky <mlevitsk@...hat.com>
To:     Parav Pandit <parav@...lanox.com>, kvm@...r.kernel.org,
        linux-kernel@...r.kernel.org, kwankhede@...dia.com,
        alex.williamson@...hat.com
Subject: Re: [PATCH 2/8] vfio/mdev: Avoid release parent reference during
 error path

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@...lanox.com>
> ---
>  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@...hat.com>

Best regards,
	Maxim Levitsky