linux-kernel - Re: [PATCH] mtd: nand: fix object reference leaks in atmel_pmecc_get_by

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Message-ID: <20190203112452.2784ef5b@bbrezillon>
Date:   Sun, 3 Feb 2019 11:24:52 +0100
From:   Boris Brezillon <bbrezillon@...nel.org>
To:     wen yang <yellowriver2010@...mail.com>
Cc:     "tudor.ambarus@...rochip.com" <tudor.ambarus@...rochip.com>,
        "miquel.raynal@...tlin.com" <miquel.raynal@...tlin.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>,
        "alexandre.belloni@...tlin.com" <alexandre.belloni@...tlin.com>,
        "nicolas.ferre@...rochip.com" <nicolas.ferre@...rochip.com>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        "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>
Subject: Re: [PATCH] mtd: nand: fix object reference leaks in
 atmel_pmecc_get_by_node

On Sun, 3 Feb 2019 09:37:31 +0000
wen yang <yellowriver2010@...mail.com> wrote:

> 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.
> 
> Signed-off-by: Wen Yang <yellowriver2010@...mail.com>
> Cc: Tudor Ambarus <tudor.ambarus@...rochip.com>
> Cc: Boris Brezillon <bbrezillon@...nel.org>
> Cc: Miquel Raynal <miquel.raynal@...tlin.com>
> Cc: Richard Weinberger <richard@....at>
> Cc: David Woodhouse <dwmw2@...radead.org>
> Cc: Brian Norris <computersforpeace@...il.com>
> Cc: Marek Vasut <marek.vasut@...il.com>
> Cc: Nicolas Ferre <nicolas.ferre@...rochip.com>
> Cc: Alexandre Belloni <alexandre.belloni@...tlin.com>
> Cc: Ludovic Desroches <ludovic.desroches@...rochip.com>
> Cc: linux-mtd@...ts.infradead.org
> Cc: linux-arm-kernel@...ts.infradead.org
> Cc: linux-kernel@...r.kernel.org
> ---
>  drivers/mtd/nand/raw/atmel/pmecc.c | 7 +++++--
>  1 file changed, 5 insertions(+), 2 deletions(-)
> 
> diff --git a/drivers/mtd/nand/raw/atmel/pmecc.c b/drivers/mtd/nand/raw/atmel/pmecc.c
> index 555a74e..bee6551 100644
> --- a/drivers/mtd/nand/raw/atmel/pmecc.c
> +++ b/drivers/mtd/nand/raw/atmel/pmecc.c
> @@ -878,14 +878,17 @@ static struct atmel_pmecc *atmel_pmecc_get_by_node(struct device *userdev,
>  	struct atmel_pmecc *pmecc, **ptr;
>  
>  	pdev = of_find_device_by_node(np);
> -	if (!pdev || !platform_get_drvdata(pdev))
> +	if (!pdev)
>  		return ERR_PTR(-EPROBE_DEFER);
> +	if (!platform_get_drvdata(pdev)) {
> +		put_device(&pdev->dev);
> +		return ERR_PTR(-EPROBE_DEFER);
> +	}
>  
>  	ptr = devres_alloc(devm_atmel_pmecc_put, sizeof(*ptr), GFP_KERNEL);
>  	if (!ptr)
>  		return ERR_PTR(-ENOMEM);

You forgot to call put_device() here. I'd suggest adding an
err_put_device label which calls put_device() before returning
ERR_PTR(ret).

>  
> -	get_device(&pdev->dev);
>  	pmecc = platform_get_drvdata(pdev);
>  
>  	*ptr = pmecc;