linux-kernel - Re: [PATCH] comedi: drivers: pcl730: Fix potential memory leak in pcl730

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Message-ID: <94fee07a-0ac4-fba7-23cb-0a9da42e25d0@mev.co.uk>
Date:   Tue, 22 Nov 2022 12:18:12 +0000
From:   Ian Abbott <abbotti@....co.uk>
To:     Shang XiaoJing <shangxiaojing@...wei.com>,
        hsweeten@...ionengravers.com, gregkh@...uxfoundation.org,
        linux-kernel@...r.kernel.org
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 <shangxiaojing@...wei.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.)

-- 
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