2022-11-22 12:44:16

by Ian Abbott

Subject: Re: [PATCH] comedi: drivers: pcl730: Fix potential memory leak in pcl730_attach()

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 <[email protected]>
> ---
> 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.)

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2022-11-22 13:21:27

by Shang XiaoJing

Subject: Re: [PATCH] comedi: drivers: pcl730: Fix potential memory leak in pcl730_attach()

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 <[email protected]>
>> ---
>>   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