linux-kernel - Re: [PATCH v2] mtd: rawnand: jz4780: fix possible object reference leak

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Message-ID: <20190205172123.13ed9469@kernel.org>
Date:   Tue, 5 Feb 2019 17:21:23 +0100
From:   Boris Brezillon <bbrezillon@...nel.org>
To:     Miquel Raynal <miquel.raynal@...tlin.com>
Cc:     Wen Yang <yellowriver2010@...mail.com>,
        "harveyhuntnexus@...il.com" <harveyhuntnexus@...il.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-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH v2] mtd: rawnand: jz4780: fix possible object reference
 leak

On Tue, 5 Feb 2019 16:55:02 +0100
Miquel Raynal <miquel.raynal@...tlin.com> wrote:

> Hi Wen,
> 
> Wen Yang <yellowriver2010@...mail.com> wrote on Tue, 5 Feb 2019
> 15:07:21 +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: ae02ab00aa3c ("mtd: nand: jz4780: driver for NAND devices on
> > JZ4780 SoCs") Signed-off-by: Wen Yang <yellowriver2010@...mail.com>
> > Suggested-by: Miquel Raynal <miquel.raynal@...tlin.com>
> > Cc: Harvey Hunt <harveyhuntnexus@...il.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: linux-mtd@...ts.infradead.org
> > Cc: linux-kernel@...r.kernel.org
> > ---
> > v2->v1: Since there is the only one user, let's remove the
> > err_put_device label.
> > 
> >  drivers/mtd/nand/raw/jz4780_bch.c | 8 +++++---
> >  1 file changed, 5 insertions(+), 3 deletions(-)
> > 
> > diff --git a/drivers/mtd/nand/raw/jz4780_bch.c
> > b/drivers/mtd/nand/raw/jz4780_bch.c index 7201827..363465c 100644
> > --- a/drivers/mtd/nand/raw/jz4780_bch.c
> > +++ b/drivers/mtd/nand/raw/jz4780_bch.c
> > @@ -281,10 +281,12 @@ static struct jz4780_bch
> > *jz4780_bch_get(struct device_node *np) struct jz4780_bch *bch;
> >  
> >  	pdev = of_find_device_by_node(np);
> > -	if (!pdev || !platform_get_drvdata(pdev))
> > +	if (!pdev)
> >  		return ERR_PTR(-EPROBE_DEFER);
> > -
> > -	get_device(&pdev->dev);
> > +	if (!platform_get_drvdata(pdev)) {
> > +		put_device(&pdev->dev);
> > +		return ERR_PTR(-EPROBE_DEFER);
> > +	}
> >  
> >  	bch = platform_get_drvdata(pdev);
> >  	clk_prepare_enable(bch->clk);  
> 
> Acked-by: Miquel Raynal <miquel.raynal@...tlin.com>

Don't plan to take that one (or any other ref leak fix) in the mtd/fixes
branch, feel free to queue it to nand/next.