linux-kernel - Re: [Patch] serial: 8250_bcm7271: fix leak in `brcmuart

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Message-ID: <e16612a6-abb3-c11c-bfe1-ad82cedeee50@gmail.com>
Date:   Thu, 27 Apr 2023 11:29:25 -0700
From:   Doug Berger <opendmb@...il.com>
To:     XuDong Liu <m202071377@...t.edu.cn>,
        Al Cooper <alcooperx@...il.com>,
        Broadcom internal kernel review list 
        <bcm-kernel-feedback-list@...adcom.com>,
        Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        Jiri Slaby <jirislaby@...nel.org>,
        Florian Fainelli <f.fainelli@...il.com>
Cc:     Dongliang Mu <dzm91@...t.edu.cn>, linux-serial@...r.kernel.org,
        linux-kernel@...r.kernel.org
Subject: Re: [Patch] serial: 8250_bcm7271: fix leak in `brcmuart_probe`

On 4/24/2023 5:51 AM, XuDong Liu wrote:
> Smatch reports:
> drivers/tty/serial/8250/8250_bcm7271.c:1120 brcmuart_probe() warn:
> 'baud_mux_clk' from clk_prepare_enable() not released on lines: 1032.
> 
> In the function brcmuart_probe(), baud_mux_clk was not correctly released
> in subsequent error handling, which may cause memory leaks.
> 
> To fix this issue, an error handling branch, err_clk_put, is added to
> release the variable using clk_put(), and an err_disable branch is added
> to meet the requirement of balancing clk_disable and clk_enable calls.
> 
> Fixes: 15ac1122fd6d ("serial: 8250_bcm7271: Fix arbitration handling")
> Signed-off-by: XuDong Liu <m202071377@...t.edu.cn>
> Reviewed-by: Dongliang Mu <dzm91@...t.edu.cn>
> ---
> The issue is discovered by static analysis, and the patch is not tested
> yet.
> ---
>   drivers/tty/serial/8250/8250_bcm7271.c | 8 ++++++--
>   1 file changed, 6 insertions(+), 2 deletions(-)
> 
> diff --git a/drivers/tty/serial/8250/8250_bcm7271.c b/drivers/tty/serial/8250/8250_bcm7271.c
> index f801b1f5b46c..b1670558868b 100644
> --- a/drivers/tty/serial/8250/8250_bcm7271.c
> +++ b/drivers/tty/serial/8250/8250_bcm7271.c
> @@ -1023,7 +1023,7 @@ static int brcmuart_probe(struct platform_device *pdev)
>   		dev_dbg(dev, "BAUD MUX clock found\n");
>   		ret = clk_prepare_enable(baud_mux_clk);
>   		if (ret)
> -			goto release_dma;
> +			goto err_clk_put;
>   		priv->baud_mux_clk = baud_mux_clk;
>   		init_real_clk_rates(dev, priv);
>   		clk_rate = priv->default_mux_rate;
> @@ -1032,7 +1032,7 @@ static int brcmuart_probe(struct platform_device *pdev)
>   	if (clk_rate == 0) {
>   		dev_err(dev, "clock-frequency or clk not defined\n");
>   		ret = -EINVAL;
> -		goto release_dma;
> +		goto err_clk_disable;
>   	}
>   
>   	dev_dbg(dev, "DMA is %senabled\n", priv->dma_enabled ? "" : "not ");
> @@ -1119,6 +1119,10 @@ static int brcmuart_probe(struct platform_device *pdev)
>   	serial8250_unregister_port(priv->line);
>   err:
>   	brcmuart_free_bufs(dev, priv);
> +err_clk_disable:
> +	clk_disable_unprepare(baud_mux_clk);
> +err_clk_put:
> +	clk_put(baud_mux_clk);
>   release_dma:
>   	if (priv->dma_enabled)
>   		brcmuart_arbitration(priv, 0);
Thank you for bringing this to my attention.

-Doug