linux-kernel - Re: [PATCH] power: supply: max17042_battery: fix the potential uninitialized use in max17042_write_verify

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Message-ID: <20191014033108.jgb2c7yy3y46l6tp@earth.universe>
Date:   Mon, 14 Oct 2019 05:31:08 +0200
From:   Sebastian Reichel <sre@...nel.org>
To:     Yizhuo <yzhai003@....edu>
Cc:     csong@...ucr.edu, zhiyunq@...ucr.edu, linux-pm@...r.kernel.org,
        linux-kernel@...r.kernel.org
Subject: Re: [PATCH] power: supply: max17042_battery: fix the potential
 uninitialized use in max17042_write_verify_reg()

Hi,

On Wed, Oct 02, 2019 at 08:44:06AM -0700, Yizhuo wrote:
> In function max17042_write_verify_reg(), variable "read_value"
> could be uninitialized if regmap_read() fails. However,
> "read_value" is used to decide the control flow later in the if
> statement, which is potentially unsafe.
> 
> Signed-off-by: Yizhuo <yzhai003@....edu>
> ---

Instead of directly failing, integrate this into
the retry loop. Also the Signed-off-by and patch
author name looks incomplete.

Thanks,

-- Sebastian

>  drivers/power/supply/max17042_battery.c | 7 +++++--
>  1 file changed, 5 insertions(+), 2 deletions(-)
> 
> diff --git a/drivers/power/supply/max17042_battery.c b/drivers/power/supply/max17042_battery.c
> index 0dfad2cf13fe..e6a2dacaa730 100644
> --- a/drivers/power/supply/max17042_battery.c
> +++ b/drivers/power/supply/max17042_battery.c
> @@ -486,12 +486,15 @@ static void max17042_external_power_changed(struct power_supply *psy)
>  static int max17042_write_verify_reg(struct regmap *map, u8 reg, u32 value)
>  {
>  	int retries = 8;
> -	int ret;
> +	int ret, err;
>  	u32 read_value;
>  
>  	do {
>  		ret = regmap_write(map, reg, value);
> -		regmap_read(map, reg, &read_value);
> +		err = regmap_read(map, reg, &read_value);
> +		if (err)
> +			return err;
> +
>  		if (read_value != value) {
>  			ret = -EIO;
>  			retries--;
> -- 
> 2.17.1
> 

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