linux-kernel - Re: [PATCH] usb: fotg210-udc: fix potential memory leak in fotg210_udc

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Message-ID: <c21591d1-7462-974e-3171-e23a0fbd7ddb@collabora.com>
Date:   Thu, 1 Dec 2022 10:38:11 +0100
From:   Andrzej Pietrasiewicz <andrzej.p@...labora.com>
To:     Yi Yang <yiyang13@...wei.com>, linus.walleij@...aro.org,
        gregkh@...uxfoundation.org
Cc:     linux-usb@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH] usb: fotg210-udc: fix potential memory leak in
 fotg210_udc_probe()

Hi Yi Yang,

You can make your patch also simplify the code.

Earlier, there's

	ret = -ENOMEM;

	/* initialize udc */
	fotg210 = kzalloc(sizeof(struct fotg210_udc), GFP_KERNEL);
	if (fotg210 == NULL)
		goto err;

and the code at the "err" label before your changes merely returns "ret".
Instead of "goto err" return -ENOMEM can be used. This, in turn,
eliminates the ret = -ENOMEM assignment. Furthermore, after applying your
patch as-is, the said "goto err;" will result with kfree(NULL) which is safe,
but unnecessary.

If you include the above changes you can add my

Reviewed-by: Andrzej Pietrasiewicz <andrzej.p@...labora.com>

W dniu 30.11.2022 o 11:12, Yi Yang pisze:
> In fotg210_udc_probe(), if devm_clk_get() or clk_prepare_enable()
> fails, 'fotg210' will not be freed, which will lead to a memory leak.
> Fix it by moving kfree() to a proper location.
> 
> Fixes: 718a38d092ec ("fotg210-udc: Handle PCLK")
> Signed-off-by: Yi Yang <yiyang13@...wei.com>
> ---
>   drivers/usb/fotg210/fotg210-udc.c | 5 ++---
>   1 file changed, 2 insertions(+), 3 deletions(-)
> 
> diff --git a/drivers/usb/fotg210/fotg210-udc.c b/drivers/usb/fotg210/fotg210-udc.c
> index b9ea6c6d931c..a366d69c1818 100644
> --- a/drivers/usb/fotg210/fotg210-udc.c
> +++ b/drivers/usb/fotg210/fotg210-udc.c
> @@ -1178,7 +1178,7 @@ int fotg210_udc_probe(struct platform_device *pdev)
>   		ret = clk_prepare_enable(fotg210->pclk);
>   		if (ret) {
>   			dev_err(dev, "failed to enable PCLK\n");
> -			return ret;
> +			goto err;
>   		}
>   	} else if (PTR_ERR(fotg210->pclk) == -EPROBE_DEFER) {
>   		/*
> @@ -1302,8 +1302,7 @@ int fotg210_udc_probe(struct platform_device *pdev)
>   	if (!IS_ERR(fotg210->pclk))
>   		clk_disable_unprepare(fotg210->pclk);
>   
> -	kfree(fotg210);
> -
>   err:
> +	kfree(fotg210);
>   	return ret;
>   }