linux-kernel - Re: [PATCH v4 1/3] mtd: rawnand: atmel: fix possible object reference leak

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Date:   Thu, 7 Feb 2019 10:23:29 +0100
From:   Miquel Raynal <miquel.raynal@...tlin.com>
To:     Wen Yang <yellowriver2010@...mail.com>
Cc:     "tudor.ambarus@...rochip.com" <tudor.ambarus@...rochip.com>,
        "bbrezillon@...nel.org" <bbrezillon@...nel.org>,
        "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 v4 1/3] mtd: rawnand: atmel: fix possible object
 reference leak

Hi Wen,

Wen Yang <yellowriver2010@...mail.com> wrote on Thu, 7 Feb 2019
03:50:55 +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>
> Suggested-by: Boris Brezillon <bbrezillon@...nel.org>

Suggested-by means that Boris suggested you to write this patch in the
first place. If he just made a review, you should drop this tag.

> Reviewed-by: Boris Brezillon <bbrezillon@...nel.org>
> Reviewed-by: Miquel Raynal <miquel.raynal@...tlin.com>

None of us gave our Reviewed-by officially, so you can drop these lines.

> Acked-by: Miquel Raynal <miquel.raynal@...tlin.com>

I gave my Acked-by because I though Boris would take the patch, but
actually he will not, so you can drop the Ack.

> 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

Please add people in Cc when you send the series and remove all these
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 | 21 +++++++++++++++------
>  1 file changed, 15 insertions(+), 6 deletions(-)
> 
> diff --git a/drivers/mtd/nand/raw/atmel/pmecc.c b/drivers/mtd/nand/raw/atmel/pmecc.c
> index 555a74e..9d39978 100644
> --- a/drivers/mtd/nand/raw/atmel/pmecc.c
> +++ b/drivers/mtd/nand/raw/atmel/pmecc.c
> @@ -876,23 +876,32 @@ 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);

New line missing here

> +	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)
> -		return ERR_PTR(-ENOMEM);
> -
> -	get_device(&pdev->dev);
> -	pmecc = platform_get_drvdata(pdev);
> +	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 };

All the comments apply to the two other patches.

Otherwise looks good.


Thanks,
Miquèl