linux-kernel - Re: [PATCH v5 1/3] mtd: rawnand: atmel: fix possible object reference leak

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Date:   Thu, 7 Feb 2019 23:21:13 +0100
From:   Miquel Raynal <miquel.raynal@...tlin.com>
To:     Wen Yang <yellowriver2010@...mail.com>
Cc:     "bbrezillon@...nel.org" <bbrezillon@...nel.org>,
        "tudor.ambarus@...rochip.com" <tudor.ambarus@...rochip.com>,
        "richard@....at" <richard@....at>,
        "dwmw2@...radead.org" <dwmw2@...radead.org>,
        "computersforpeace@...il.com" <computersforpeace@...il.com>,
        "marek.vasut@...il.com" <marek.vasut@...il.com>,
        "nicolas.ferre@...rochip.com" <nicolas.ferre@...rochip.com>,
        "alexandre.belloni@...tlin.com" <alexandre.belloni@...tlin.com>,
        "ludovic.desroches@...rochip.com" <ludovic.desroches@...rochip.com>,
        "linux-mtd@...ts.infradead.org" <linux-mtd@...ts.infradead.org>,
        "linux-arm-kernel@...ts.infradead.org" 
        <linux-arm-kernel@...ts.infradead.org>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH v5 1/3] mtd: rawnand: atmel: fix possible object
 reference leak

Hi Wen,

Wen Yang <yellowriver2010@...mail.com> wrote on Thu, 7 Feb 2019
11:56:48 +0000:

> of_find_device_by_node() takes a reference to the struct device
> when it finds a match via get_device, there is no need to call
> get_device() twice.
> We also should make sure to drop the reference to the device
> taken by of_find_device_by_node() on driver unbind.
> 
> Fixes: f88fc122cc34 ("mtd: nand: Cleanup/rework the atmel_nand driver")
> Signed-off-by: Wen Yang <yellowriver2010@...mail.com>
> ---
> v5->v4: Add new line, add people in Cc and remove all Cc lines.
> v4->v3: Avoid two times of calling grtform_get_drvdata()
> v3->v2: Change the commit message.
> v2->v1: Add missing Fixes tag.
> 
>  drivers/mtd/nand/raw/atmel/pmecc.c | 22 ++++++++++++++++------
>  1 file changed, 16 insertions(+), 6 deletions(-)
> 
> diff --git a/drivers/mtd/nand/raw/atmel/pmecc.c b/drivers/mtd/nand/raw/atmel/pmecc.c
> index 555a74e..97e47ea 100644
> --- a/drivers/mtd/nand/raw/atmel/pmecc.c
> +++ b/drivers/mtd/nand/raw/atmel/pmecc.c
> @@ -876,23 +876,33 @@ static struct atmel_pmecc *atmel_pmecc_get_by_node(struct device *userdev,
>  {
>  	struct platform_device *pdev;
>  	struct atmel_pmecc *pmecc, **ptr;
> +	int ret;
>  
>  	pdev = of_find_device_by_node(np);
> -	if (!pdev || !platform_get_drvdata(pdev))
> +	if (!pdev)
>  		return ERR_PTR(-EPROBE_DEFER);
>  
> -	ptr = devres_alloc(devm_atmel_pmecc_put, sizeof(*ptr), GFP_KERNEL);
> -	if (!ptr)
> -		return ERR_PTR(-ENOMEM);
> -
> -	get_device(&pdev->dev);
>  	pmecc = platform_get_drvdata(pdev);
> +	if (!pmecc) {
> +		ret = -EPROBE_DEFER;
> +		goto err_put_device;
> +	}
> +
> +	ptr = devres_alloc(devm_atmel_pmecc_put, sizeof(*ptr), GFP_KERNEL);
> +	if (!ptr) {
> +		ret = -ENOMEM;
> +		goto err_put_device;
> +	}
>  
>  	*ptr = pmecc;
>  
>  	devres_add(userdev, ptr);
>  
>  	return pmecc;
> +
> +err_put_device:
> +	put_device(&pdev->dev);
> +	return ERR_PTR(ret);
>  }
>  
>  static const int atmel_pmecc_strengths[] = { 2, 4, 8, 12, 24, 32 };

Series applied to nand/next.


Thanks,
Miquèl