Message-ID: <58ebc58b-f8fc-06a7-b152-1709894da8e3@kernel.org>
Date:   Thu, 13 Jan 2022 08:35:14 +0100
MIME-Version: 1.0
User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:91.0) Gecko/20100101
 Thunderbird/91.4.1
Subject: Re: [PATCH v2] tty/serial: Check for null pointer after calling
 devm_ioremap
Content-Language: en-US
To:     Jiasheng Jiang <jiasheng@iscas.ac.cn>, gregkh@linuxfoundation.org
Cc:     linux-serial@vger.kernel.org, linux-kernel@vger.kernel.org
References: <20220107144852.4081390-1-jiasheng@iscas.ac.cn>
From:   Jiri Slaby <jirislaby@kernel.org>
In-Reply-To: <20220107144852.4081390-1-jiasheng@iscas.ac.cn>
Content-Type: text/plain; charset=UTF-8; format=flowed
Content-Transfer-Encoding: 7bit
Precedence: bulk

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@iscas.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