linux-kernel - Re: [PATCH v1] platform/x86/dell/dell-rbtn: Fix resources leaking on error path

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Date:   Mon, 12 Jun 2023 19:52:05 +0200
From:   Pali Rohár <pali@...nel.org>
To:     Michal Wilczynski <michal.wilczynski@...el.com>
Cc:     linux-acpi@...r.kernel.org, rafael@...nel.org,
        andriy.shevchenko@...el.com, ilpo.jarvinen@...ux.intel.com,
        hdegoede@...hat.com, markgross@...nel.org, fengguang.wu@...el.com,
        dvhart@...ux.intel.com, platform-driver-x86@...r.kernel.org,
        linux-kernel@...r.kernel.org
Subject: Re: [PATCH v1] platform/x86/dell/dell-rbtn: Fix resources leaking on
 error path

On Monday 12 June 2023 12:02:50 Michal Wilczynski wrote:
> Currently rbtn_add() in case of failure is leaking resources. Fix this
> by adding a proper rollback. While at it, remove unnecessary assignment
> of NULL to device->driver_data and unnecessary whitespace, plus add a
> break for the default case in a switch.
> 
> Suggested-by: Ilpo Järvinen <ilpo.jarvinen@...ux.intel.com>
> Fixes: 817a5cdb40c8 ("dell-rbtn: Dell Airplane Mode Switch driver")
> Signed-off-by: Michal Wilczynski <michal.wilczynski@...el.com>
> Reviewed-by: Andy Shevchenko <andriy.shevchenko@...ux.intel.com>
> ---
>  drivers/platform/x86/dell/dell-rbtn.c | 5 +++--
>  1 file changed, 3 insertions(+), 2 deletions(-)
> 
> diff --git a/drivers/platform/x86/dell/dell-rbtn.c b/drivers/platform/x86/dell/dell-rbtn.c
> index aa0e6c907494..e9b3f9c3ab7d 100644
> --- a/drivers/platform/x86/dell/dell-rbtn.c
> +++ b/drivers/platform/x86/dell/dell-rbtn.c
> @@ -420,10 +420,12 @@ static int rbtn_add(struct acpi_device *device)
>  		break;
>  	default:
>  		ret = -EINVAL;
> +		break;
>  	}
> +	if (ret)
> +		rbtn_acquire(device, false);
>  
>  	return ret;
> -
>  }

Hello! I'm looking at rbtn_add() function and there is also code:

	rbtn_data = devm_kzalloc(&device->dev, sizeof(*rbtn_data), GFP_KERNEL);
	if (!rbtn_data)
		return -ENOMEM;

which is called after rbtn_acquire(). So it looks like when kzalloc
fails then there is another leak...

>  
>  static void rbtn_remove(struct acpi_device *device)
> @@ -442,7 +444,6 @@ static void rbtn_remove(struct acpi_device *device)
>  	}
>  
>  	rbtn_acquire(device, false);
> -	device->driver_data = NULL;
>  }
>  
>  static void rbtn_notify(struct acpi_device *device, u32 event)
> -- 
> 2.40.1
>