linux-kernel - Re: [PATCH] mfd: max77843: Fix max77843_chg

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Message-ID: <CAJKOXPc8JWxzo1ySDHrRQ-jDWdsSoMSXTwPgF+O_hASwXCCXug@mail.gmail.com>
Date:	Tue, 15 Sep 2015 11:20:01 +0900
From:	Krzysztof Kozlowski <k.kozlowski@...sung.com>
To:	Javier Martinez Canillas <javier@....samsung.com>
Cc:	linux-kernel@...r.kernel.org, Lee Jones <lee.jones@...aro.org>,
	Samuel Ortiz <sameo@...ux.intel.com>
Subject: Re: [PATCH] mfd: max77843: Fix max77843_chg_init() return on error

2015-09-14 17:23 GMT+09:00 Javier Martinez Canillas <javier@....samsung.com>:
> If i2c_new_dummy() fails in max77843_chg_init(), an PTR_ERR(NULL) is
> returned which is 0. So the function was wrongly returning a success
> value instead of an error code.
>
> Fixes: c7f585fe46d8 ("mfd: max77843: Add max77843 MFD driver core driver")
> Signed-off-by: Javier Martinez Canillas <javier@....samsung.com>
>
> ---
>
>  drivers/mfd/max77843.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)

Nice catch. I think this should go to stable. I did not try to
reproduce it but looking at the code this should lead to NULL pointer
exceptions on:
1. first access to max77843->regmap_chg (this won't actually happen
because charger driver was not merged);
2. first dereference of pointer returned by i2c_get_clientdata() which
will happen on first system suspend or device unbind/removal.

Reviewed-by: Krzysztof Kozlowski <k.kozlowski@...sung.com>

Best regards,
Krzysztof

>
> diff --git a/drivers/mfd/max77843.c b/drivers/mfd/max77843.c
> index c52162ea3d0a..586098f1b233 100644
> --- a/drivers/mfd/max77843.c
> +++ b/drivers/mfd/max77843.c
> @@ -80,7 +80,7 @@ static int max77843_chg_init(struct max77693_dev *max77843)
>         if (!max77843->i2c_chg) {
>                 dev_err(&max77843->i2c->dev,
>                                 "Cannot allocate I2C device for Charger\n");
> -               return PTR_ERR(max77843->i2c_chg);
> +               return -ENODEV;
>         }
>         i2c_set_clientdata(max77843->i2c_chg, max77843);
>
> --
> 2.4.3
>
> --
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