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

From: Miquel Raynal <miquel.raynal@bootlin.com>
To: Wen Yang <yellowriver2010@hotmail.com>
Cc: "alexandre.belloni@bootlin.com" <alexandre.belloni@bootlin.com>,
	"tudor.ambarus@microchip.com" <tudor.ambarus@microchip.com>,
	"richard@nod.at" <richard@nod.at>,
	"bbrezillon@kernel.org" <bbrezillon@kernel.org>,
	"nicolas.ferre@microchip.com" <nicolas.ferre@microchip.com>,
	"linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
	"marek.vasut@gmail.com" <marek.vasut@gmail.com>,
	"ludovic.desroches@microchip.com"
	<ludovic.desroches@microchip.com>,
	"linux-mtd@lists.infradead.org" <linux-mtd@lists.infradead.org>,
	"computersforpeace@gmail.com" <computersforpeace@gmail.com>,
	"dwmw2@infradead.org" <dwmw2@infradead.org>,
	"linux-arm-kernel@lists.infradead.org"
	<linux-arm-kernel@lists.infradead.org>
Subject: Re: [PATCH v5 1/3] mtd: rawnand: atmel: fix possible object reference leak
Date: Thu, 7 Feb 2019 23:21:13 +0100	[thread overview]
Message-ID: <20190207232113.5dc026af@xps13> (raw)
In-Reply-To: <HK0PR02MB3634B38A3D04DCFFC09BDCB0B2680@HK0PR02MB3634.apcprd02.prod.outlook.com>

Hi Wen,

Wen Yang <yellowriver2010@hotmail.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@hotmail.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

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