linux-kernel - Re: [PATCH v2] wlcore: sdio: Fix a memory leaking bug in wl1271

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Date:   Fri, 24 May 2019 10:28:39 +0100
From:   Jon Hunter <jonathanh@...dia.com>
To:     Gen Zhang <blackgod016574@...il.com>,
        Kalle Valo <kvalo@...eaurora.org>
CC:     <linux-wireless@...r.kernel.org>, <netdev@...r.kernel.org>,
        <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH v2] wlcore: sdio: Fix a memory leaking bug in
 wl1271_probe()


On 24/05/2019 03:43, Gen Zhang wrote:
> In wl1271_probe(), 'glue->core' is allocated by platform_device_alloc(),
> when this allocation fails, ENOMEM is returned. However, 'pdev_data'
> and 'glue' are allocated by devm_kzalloc() before 'glue->core'. When
> platform_device_alloc() returns NULL, we should also free 'pdev_data'
> and 'glue' before wl1271_probe() ends to prevent leaking memory.

No, devm_kzalloc() automatically frees memory on failure.

> Similarly, we should free 'pdev_data' when 'glue' is NULL. And we
> should free 'pdev_data' and 'glue' when 'ret' is error.
> 
> Further, we shoulf free 'glue->dev', 'pdev_data' and 'glue' when this
> function normally ends to prevent memory leaking.

Why?

> Signed-off-by: Gen Zhang <blackgod016574@...il.com>
> ---
> diff --git a/drivers/net/wireless/ti/wlcore/sdio.c b/drivers/net/wireless/ti/wlcore/sdio.c
> index 4d4b0770..9110891 100644
> --- a/drivers/net/wireless/ti/wlcore/sdio.c
> +++ b/drivers/net/wireless/ti/wlcore/sdio.c
> @@ -298,8 +298,10 @@ static int wl1271_probe(struct sdio_func *func,
>  	pdev_data->if_ops = &sdio_ops;
>  
>  	glue = devm_kzalloc(&func->dev, sizeof(*glue), GFP_KERNEL);
> -	if (!glue)
> -		return -ENOMEM;
> +	if (!glue) {
> +		ret = -ENOMEM;
> +		goto out_free1;
> +	}
>  
>  	glue->dev = &func->dev;
>  
> @@ -311,7 +313,7 @@ static int wl1271_probe(struct sdio_func *func,
>  
>  	ret = wlcore_probe_of(&func->dev, &irq, &wakeirq, pdev_data);
>  	if (ret)
> -		goto out;
> +		goto out_free2;
>  
>  	/* if sdio can keep power while host is suspended, enable wow */
>  	mmcflags = sdio_get_host_pm_caps(func);
> @@ -340,7 +342,7 @@ static int wl1271_probe(struct sdio_func *func,
>  	if (!glue->core) {
>  		dev_err(glue->dev, "can't allocate platform_device");
>  		ret = -ENOMEM;
> -		goto out;
> +		goto out_free2;
>  	}
>  
>  	glue->core->dev.parent = &func->dev;
> @@ -380,12 +382,17 @@ static int wl1271_probe(struct sdio_func *func,
>  		dev_err(glue->dev, "can't add platform device\n");
>  		goto out_dev_put;
>  	}
> -	return 0;
> +	ret = 0;

This is completely wrong.

>  out_dev_put:
>  	platform_device_put(glue->core);
>  
> -out:
> +out_free2:
> +	devm_kfree(&func->dev, glue);
> +
> +out_free1:
> +	devm_kfree(&func->dev, pdev_data);
> +
>  	return ret;
>  }
>  
> ---

Jon

-- 
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