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

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Message-ID: <f2ae728a-d816-02d3-cefd-500a74f08003@huawei.com>
Date:   Mon, 18 Oct 2021 11:03:24 +0800
From:   Yang Yingliang <yangyingliang@...wei.com>
To:     Wolfram Sang <wsa@...nel.org>, <linux-kernel@...r.kernel.org>,
        <linux-i2c@...r.kernel.org>
Subject: Re: [PATCH] i2c: core: Fix possible memleak in
 i2c_new_client_device()

Hi,

On 2021/10/17 23:27, Wolfram Sang wrote:
>> 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?
The reference is initialized in device_initialize() called in 
device_register(), if device_register()
fails, the 'kobj->name' is leaked.

Thanks,
Yang
>
>> 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
>>