linux-kernel - Re: [PATCH] media: davinci: vpif_capture: fix memory leak in vpif

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Date:   Mon, 3 Jun 2019 13:55:00 +0200
From:   Hans Verkuil <hverkuil@...all.nl>
To:     Young Xiao <92siuyang@...il.com>, prabhakar.csengg@...il.com,
        mchehab@...nel.org, linux-media@...r.kernel.org,
        linux-kernel@...r.kernel.org
Subject: Re: [PATCH] media: davinci: vpif_capture: fix memory leak in
 vpif_probe()

On 5/29/19 3:09 PM, Young Xiao wrote:
> If vpif_probe() fails on vpif_probe_complete(), then memory
> allocated at initialize_vpif() for global vpif_obj.dev[i]
> become unreleased.
> 
> The patch adds deallocation of vpif_obj.dev[i] on the error path.
> 
> Signed-off-by: Young Xiao <92siuyang@...il.com>
> ---
>  drivers/media/platform/davinci/vpif_capture.c | 16 ++++++++++++++--
>  1 file changed, 14 insertions(+), 2 deletions(-)
> 
> diff --git a/drivers/media/platform/davinci/vpif_capture.c b/drivers/media/platform/davinci/vpif_capture.c
> index b5aacb0..63e6ec4 100644
> --- a/drivers/media/platform/davinci/vpif_capture.c
> +++ b/drivers/media/platform/davinci/vpif_capture.c
> @@ -1621,6 +1621,14 @@ vpif_capture_get_pdata(struct platform_device *pdev)
>  	return NULL;
>  }
>  
> +static void free_vpif_objs(void)
> +{
> +	int i;
> +
> +	for (i = 0; i < VPIF_DISPLAY_MAX_DEVICES; i++)
> +		kfree(vpif_obj.dev[i]);
> +}
> +
>  /**
>   * vpif_probe : This function probes the vpif capture driver
>   * @pdev: platform device pointer
> @@ -1701,7 +1709,10 @@ static __init int vpif_probe(struct platform_device *pdev)
>  				  "registered sub device %s\n",
>  				   subdevdata->name);
>  		}
> -		vpif_probe_complete();
> +		err = vpif_probe_complete();
> +		if (err) {
> +			goto probe_subdev_out;
> +		}

No need for { and } as per kernel coding style.

>  	} else {
>  		vpif_obj.notifier.ops = &vpif_async_ops;
>  		err = v4l2_async_notifier_register(&vpif_obj.v4l2_dev,
> @@ -1722,6 +1733,7 @@ static __init int vpif_probe(struct platform_device *pdev)
>  	v4l2_device_unregister(&vpif_obj.v4l2_dev);
>  cleanup:
>  	v4l2_async_notifier_cleanup(&vpif_obj.notifier);
> +	free_vpif_objs();

This would break the case where initialize_vpif() returns an error, since
initialize_vpif already frees these objects on error.

In this case the easiest way of doing this is to just return if initialize_vpif
returns an error. No need to clean up anything.

Regards,

	Hans

>  
>  	return err;
>  }
> @@ -1748,8 +1760,8 @@ static int vpif_remove(struct platform_device *device)
>  		ch = vpif_obj.dev[i];
>  		/* Unregister video device */
>  		video_unregister_device(&ch->video_dev);
> -		kfree(vpif_obj.dev[i]);
>  	}
> +	free_vpif_objs()
>  	return 0;
>  }
>  
>