linux-kernel - Re: [PATCH v2] tty/serial: Check for null pointer after calling devm

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Message-ID: <58ebc58b-f8fc-06a7-b152-1709894da8e3@kernel.org>
Date:   Thu, 13 Jan 2022 08:35:14 +0100
From:   Jiri Slaby <jirislaby@...nel.org>
To:     Jiasheng Jiang <jiasheng@...as.ac.cn>, gregkh@...uxfoundation.org
Cc:     linux-serial@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH v2] tty/serial: Check for null pointer after calling
 devm_ioremap

On 07. 01. 22, 15:48, Jiasheng Jiang wrote:
> As the possible failure of the devres_alloc(), the devm_ioremap()
> may return NULL pointer.
> And the 'port->membase' will be used in mlb_usio_startup() without the
> check.
> Therefore, in order to avoid the dereference of the NULL pointer, it
> should be better to add the check to guarantee the success of the probe.
> 
> Fixes: ba44dc043004 ("serial: Add Milbeaut serial control")
> Signed-off-by: Jiasheng Jiang <jiasheng@...as.ac.cn>
> ---
> Changelog
> 
> v1 -> v2
> 
> * Change 1. Refine the commit message to be more clear.
> ---
>   drivers/tty/serial/milbeaut_usio.c | 4 ++++
>   1 file changed, 4 insertions(+)
> 
> diff --git a/drivers/tty/serial/milbeaut_usio.c b/drivers/tty/serial/milbeaut_usio.c
> index 8f2cab7f66ad..1ecbf6d0dc79 100644
> --- a/drivers/tty/serial/milbeaut_usio.c
> +++ b/drivers/tty/serial/milbeaut_usio.c
> @@ -523,6 +523,10 @@ static int mlb_usio_probe(struct platform_device *pdev)
>   	}
>   	port->membase = devm_ioremap(&pdev->dev, res->start,
>   				resource_size(res));
> +	if (!port->membase) {
> +		ret = -ENOMEM;
> +		goto failed;
> +	}

Hi,

what about using devm_ioremap_resource() and have only one if there?

thanks,
-- 
js
suse labs