linux-kernel - Re: [PATCH] [media] media-entity: only call dev_dbg

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Date:   Fri, 7 Apr 2017 10:40:15 +0300
From:   Sakari Ailus <sakari.ailus@....fi>
To:     Helen Koike <helen.koike@...labora.com>
Cc:     linux-media@...r.kernel.org, mchehab@...nel.org,
        linux-kernel@...r.kernel.org
Subject: Re: [PATCH] [media] media-entity: only call dev_dbg_obj if mdev is
 not NULL

Hi Helen,

On Thu, Apr 06, 2017 at 04:32:00PM -0300, Helen Koike wrote:
> Fix kernel Oops NULL pointer deference
> Call dev_dbg_obj only after checking if gobj->mdev is not NULL
> 
> Signed-off-by: Helen Koike <helen.koike@...labora.com>
> ---
>  drivers/media/media-entity.c | 4 ++--
>  1 file changed, 2 insertions(+), 2 deletions(-)
> 
> diff --git a/drivers/media/media-entity.c b/drivers/media/media-entity.c
> index 5640ca2..bc44193 100644
> --- a/drivers/media/media-entity.c
> +++ b/drivers/media/media-entity.c
> @@ -199,12 +199,12 @@ void media_gobj_create(struct media_device *mdev,
>  
>  void media_gobj_destroy(struct media_gobj *gobj)
>  {
> -	dev_dbg_obj(__func__, gobj);
> -
>  	/* Do nothing if the object is not linked. */
>  	if (gobj->mdev == NULL)
>  		return;
>  
> +	dev_dbg_obj(__func__, gobj);
> +
>  	gobj->mdev->topology_version++;
>  
>  	/* Remove the object from mdev list */

Where is media_gobj_destroy() called with an object with NULL mdev?

I do not object to the change, but would like to know because I don't think
it's supposed to happen.

There are issues though, until the patches fixing object referencing are
finished and merged. Unfortunately I haven't been able to work on those
recently, will pick them up again soon...

-- 
Kind regards,

Sakari Ailus
e-mail: sakari.ailus@....fi	XMPP: sailus@...iisi.org.uk