[PATCH] power: supply: max17042_battery: fix the potential uninitialized use in max17042_write_verify_reg()

[PATCH] power: supply: max17042_battery: fix the potential uninitialized use in max17042_write_verify_reg()

[Yizhuo]

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@ucr.edu>
---
 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

Re: [PATCH] power: supply: max17042_battery: fix the potential uninitialized use in max17042_write_verify_reg()

[Sebastian Reichel]

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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@ucr.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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