linux-kernel - Re: [PATCH v3] i2c: busses/i2c-pxa.c: fix potential null pointer dereference error

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Message-ID: <CAN1soZwMX8jDdaAhBPBojW0PA3Dyt8sq9QGr-F=worw+7WHMmg@mail.gmail.com>
Date:	Fri, 15 Feb 2013 00:10:54 +0800
From:	Haojian Zhuang <haojian.zhuang@...il.com>
To:	Cong Ding <dinggnu@...il.com>
Cc:	Kyungmin Park <kmpark@...radead.org>,
	Wolfram Sang <w.sang@...gutronix.de>,
	Andrew Morton <akpm@...ux-foundation.org>,
	Karol Lewandowski <k.lewandowsk@...sung.com>,
	Haojian Zhuang <haojian.zhuang@...vell.com>,
	linux-i2c@...r.kernel.org,
	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH v3] i2c: busses/i2c-pxa.c: fix potential null pointer
 dereference error

On Thu, Feb 14, 2013 at 7:28 PM, Cong Ding <dinggnu@...il.com> wrote:
> If it goes to eclk through line 1107, the variable res would be NULL. It will
> cause a null pointer dereference error if we call release_mem_region. The
> correct way should be using devm_kzalloc rather than kzalloc to allocate
> memory.
>
> Signed-off-by: Cong Ding <dinggnu@...il.com>
> ---
>  drivers/i2c/busses/i2c-pxa.c |   22 ++++++++--------------
>  1 file changed, 8 insertions(+), 14 deletions(-)
>
> diff --git a/drivers/i2c/busses/i2c-pxa.c b/drivers/i2c/busses/i2c-pxa.c
> index 1034d93..dd2d640 100644
> --- a/drivers/i2c/busses/i2c-pxa.c
> +++ b/drivers/i2c/busses/i2c-pxa.c
> @@ -1094,29 +1094,23 @@ static int i2c_pxa_probe(struct platform_device *dev)
>         struct resource *res = NULL;
>         int ret, irq;
>
> -       i2c = kzalloc(sizeof(struct pxa_i2c), GFP_KERNEL);
> -       if (!i2c) {
> -               ret = -ENOMEM;
> -               goto emalloc;
> -       }
> +       i2c = devm_kzalloc(sizeof(struct pxa_i2c), GFP_KERNEL);
> +       if (!i2c)
> +               return -ENOMEM;
>
>         ret = i2c_pxa_probe_dt(dev, i2c, &i2c_type);
>         if (ret > 0)
>                 ret = i2c_pxa_probe_pdata(dev, i2c, &i2c_type);
>         if (ret < 0)
> -               goto eclk;
> +               return ret;
>
>         res = platform_get_resource(dev, IORESOURCE_MEM, 0);
>         irq = platform_get_irq(dev, 0);
> -       if (res == NULL || irq < 0) {
> -               ret = -ENODEV;
> -               goto eclk;
> -       }
> +       if (res == NULL || irq < 0)
> +               return -ENODEV;
>
> -       if (!request_mem_region(res->start, resource_size(res), res->name)) {
> -               ret = -ENOMEM;
> -               goto eclk;
> -       }
> +       if (!request_mem_region(res->start, resource_size(res), res->name))
> +               return -ENOMEM;
>
>         i2c->adap.owner   = THIS_MODULE;
>         i2c->adap.retries = 5;
> --
> 1.7.9.5
>

Acked-by: Haojian Zhuang <haojian.zhuang@...il.com>
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