[PATCH] power: supply: max17042_battery: fix some usage of uninitialized variables

[Yizhuo]

Several functions in this file are trying to use regmap_read() to
initialize the specific variable, however, if regmap_read() fails,
the variable could be uninitialized but used directly, which is
potentially unsafe. The return value of regmap_read() should be
checked and handled. The same case also happens in function
max17042_thread_handler() but it needs more effort to patch.

Signed-off-by: Yizhuo <yzhai...@ucr.edu>
---
 drivers/power/supply/max17042_battery.c | 23 +++++++++++++++++++----
 1 file changed, 19 insertions(+), 4 deletions(-)

diff --git a/drivers/power/supply/max17042_battery.c 
b/drivers/power/supply/max17042_battery.c
index e6a2dacaa730..8e5727010ed2 100644
--- a/drivers/power/supply/max17042_battery.c
+++ b/drivers/power/supply/max17042_battery.c
@@ -675,8 +675,12 @@ static void max17042_reset_vfsoc0_reg(struct max17042_chip 
*chip)
 {
        unsigned int vfSoc;
        struct regmap *map = chip->regmap;
+       int ret;
+
+       ret = regmap_read(map, MAX17042_VFSOC, &vfSoc);
+       if (ret)
+               return;
 
-       regmap_read(map, MAX17042_VFSOC, &vfSoc);
        regmap_write(map, MAX17042_VFSOC0Enable, VFSOC0_UNLOCK);
        max17042_write_verify_reg(map, MAX17042_VFSOC0, vfSoc);
        regmap_write(map, MAX17042_VFSOC0Enable, VFSOC0_LOCK);
@@ -686,12 +690,18 @@ static void max17042_load_new_capacity_params(struct 
max17042_chip *chip)
 {
        u32 full_cap0, rep_cap, dq_acc, vfSoc;
        u32 rem_cap;
+       int ret;
 
        struct max17042_config_data *config = chip->pdata->config_data;
        struct regmap *map = chip->regmap;
 
-       regmap_read(map, MAX17042_FullCAP0, &full_cap0);
-       regmap_read(map, MAX17042_VFSOC, &vfSoc);
+       ret = regmap_read(map, MAX17042_FullCAP0, &full_cap0);
+       if (ret)
+               return ret;
+
+       ret = regmap_read(map, MAX17042_VFSOC, &vfSoc);
+       if (ret)
+               return ret;
 
        /* fg_vfSoc needs to shifted by 8 bits to get the
         * perc in 1% accuracy, to get the right rem_cap multiply
@@ -1108,7 +1118,12 @@ static int max17042_probe(struct i2c_client *client,
        if (!client->irq)
                regmap_write(chip->regmap, MAX17042_SALRT_Th, 0xff00);
 
-       regmap_read(chip->regmap, MAX17042_STATUS, &val);
+       ret = regmap_read(chip->regmap, MAX17042_STATUS, &val);
+       if (ret) {
+               dev_err(&client->dev, "Failed to get MAX17042_STATUS.\n");
+               return ret;
+       }
+
        if (val & STATUS_POR_BIT) {
                INIT_WORK(&chip->work, max17042_init_worker);
                ret = devm_add_action(&client->dev, max17042_stop_work, chip);
-- 
2.17.1