Received-SPF: pass (google.com: domain of linux-kernel-owner@vger.kernel.org designates 2620:137:e000::1:20 as permitted sender) client-ip=2620:137:e000::1:20;
Message-ID: <2f4dc5e8-1b2c-e071-a363-d3f509cc4ccc@huawei.com>
Date:   Tue, 22 Nov 2022 20:24:09 +0800
MIME-Version: 1.0
User-Agent: Mozilla/5.0 (Windows NT 10.0; Win64; x64; rv:102.0) Gecko/20100101
 Thunderbird/102.1.0
Subject: Re: [PATCH] comedi: drivers: pcl730: Fix potential memory leak in
 pcl730_attach()
To:     Ian Abbott <abbotti@mev.co.uk>, <hsweeten@visionengravers.com>,
        <gregkh@linuxfoundation.org>, <linux-kernel@vger.kernel.org>
References: <20221122120428.25069-1-shangxiaojing@huawei.com>
 <94fee07a-0ac4-fba7-23cb-0a9da42e25d0@mev.co.uk>
From:   shangxiaojing <shangxiaojing@huawei.com>
In-Reply-To: <94fee07a-0ac4-fba7-23cb-0a9da42e25d0@mev.co.uk>
Content-Type: text/plain; charset="UTF-8"; format=flowed
Content-Transfer-Encoding: 8bit
Precedence: bulk


On 2022/11/22 20:18, Ian Abbott wrote:
> On 22/11/2022 12:04, Shang XiaoJing wrote:
>> pcl730_attach() calls comedi_request_region() and won't release the
>> resource allocated by alloc_resource() when pcl730_attach() failed 
>> latter.
>> Add release_region() to prevent memory leak.
>>
>> Fixes: 6f9aa29b47f6 ("staging: comedi: pcl730: use 
>> comedi_request_region()")
>> Signed-off-by: Shang XiaoJing <shangxiaojing@huawei.com>
>> ---
>>   drivers/comedi/drivers/pcl730.c | 8 +++++++-
>>   1 file changed, 7 insertions(+), 1 deletion(-)
>>
>> diff --git a/drivers/comedi/drivers/pcl730.c 
>> b/drivers/comedi/drivers/pcl730.c
>> index d2733cd5383d..c463de8a14e1 100644
>> --- a/drivers/comedi/drivers/pcl730.c
>> +++ b/drivers/comedi/drivers/pcl730.c
>> @@ -274,8 +274,14 @@ static int pcl730_attach(struct comedi_device *dev,
>>           return ret;
>>       ret = comedi_alloc_subdevices(dev, board->n_subdevs);
>> -    if (ret)
>> +    if (ret) {
>> +        if (dev->iobase && dev->iolen) {
>> +            release_region(dev->iobase, dev->iolen);
>> +            dev->iobase = 0;
>> +            dev->iolen = 0;
>> +        }
>>           return ret;
>> +    }
>>       subdev = 0;
> 
> This is not needed.  If the 'attach' handler pcl730_attach() returns an 
> error, the 'detach' handler comedi_legacy_detach() will be called to 
> clean up the allocated resources.  All the comedi drivers work that way. 
> (A lot of them have an 'auto_attach' handler instead of an 'attach' 
> handler, but the error handling is basically the same.)
> 

ok, thanks for the advice!

Thanks,
-- 
Shang XiaoJing