linux-kernel - Re: [PATCH] i2c: core: Fix possible memleak in i2c_new_client

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Date:   Sun, 17 Oct 2021 17:27:18 +0200
From:   Wolfram Sang <wsa@...nel.org>
To:     Yang Yingliang <yangyingliang@...wei.com>
Cc:     linux-kernel@...r.kernel.org, linux-i2c@...r.kernel.org
Subject: Re: [PATCH] i2c: core: Fix possible memleak in
 i2c_new_client_device()


> In error path after calling i2c_dev_set_name(), the put_device()
> should be used to give up the device reference, then the name
> allocated in dev_set_name() will be freed in kobject_cleanup().

I don't see it. dev_set_name does not call device_get, so why should we
call device_put on failure? No other user of dev_set_name seems to do
this. So, if this is an imbalance, where does the unmatched get_device
really come from?

> 
> Reported-by: Hulk Robot <hulkci@...wei.com>
> Signed-off-by: Yang Yingliang <yangyingliang@...wei.com>
> ---
>  drivers/i2c/i2c-core-base.c | 13 +++++++------
>  1 file changed, 7 insertions(+), 6 deletions(-)
> 
> diff --git a/drivers/i2c/i2c-core-base.c b/drivers/i2c/i2c-core-base.c
> index 54964fbe3f03..190d4fd5e594 100644
> --- a/drivers/i2c/i2c-core-base.c
> +++ b/drivers/i2c/i2c-core-base.c
> @@ -1047,8 +1047,6 @@ i2c_new_client_device(struct i2c_adapter *adap, struct i2c_board_info const *inf
>  	client->dev.of_node = of_node_get(info->of_node);
>  	client->dev.fwnode = info->fwnode;
>  
> -	i2c_dev_set_name(adap, client, info);
> -
>  	if (info->swnode) {
>  		status = device_add_software_node(&client->dev, info->swnode);
>  		if (status) {
> @@ -1059,17 +1057,20 @@ i2c_new_client_device(struct i2c_adapter *adap, struct i2c_board_info const *inf
>  		}
>  	}
>  
> +	i2c_dev_set_name(adap, client, info);
>  	status = device_register(&client->dev);
> -	if (status)
> -		goto out_remove_swnode;
> +	if (status) {
> +		device_remove_software_node(&client->dev);
> +		of_node_put(info->of_node);
> +		put_device(&client->dev);
> +		return ERR_PTR(status);
> +	}
>  
>  	dev_dbg(&adap->dev, "client [%s] registered with bus id %s\n",
>  		client->name, dev_name(&client->dev));
>  
>  	return client;
>  
> -out_remove_swnode:
> -	device_remove_software_node(&client->dev);
>  out_err_put_of_node:
>  	of_node_put(info->of_node);
>  out_err:
> -- 
> 2.25.1
> 

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