[PATCH 06/11] power: supply: max17042: avoid overflow when determining health

[André Draszik]

If vmax has the default value of INT_MAX (e.g. because not specified in
DT), battery health is reported as over-voltage. This is because adding
any value to vmax (the vmax tolerance in this case) causes it to wrap
around, making it negative and smaller than the measured battery
voltage.

Avoid that by using size_add().

Signed-off-by: André Draszik <andre.draszik@xxxxxxxxxx>
---
 drivers/power/supply/max17042_battery.c | 6 +++++-
 1 file changed, 5 insertions(+), 1 deletion(-)

diff --git a/drivers/power/supply/max17042_battery.c b/drivers/power/supply/max17042_battery.c
index b9277f81a25d..8808c0d2ad10 100644
--- a/drivers/power/supply/max17042_battery.c
+++ b/drivers/power/supply/max17042_battery.c
@@ -201,7 +201,11 @@ static int max17042_get_battery_health(struct max17042_chip *chip, int *health)
 		goto out;
 	}
 
-	if (vbatt > chip->pdata->vmax + MAX17042_VMAX_TOLERANCE) {
+	/* avoid
+	 * /sys/class/power_supply/max170xx_battery/health:Over voltage
+	 * due to overflow
+	 */
+	if (vbatt > size_add(chip->pdata->vmax, MAX17042_VMAX_TOLERANCE)) {
 		*health = POWER_SUPPLY_HEALTH_OVERVOLTAGE;
 		goto out;
 	}

-- 
2.53.0.414.gf7e9f6c205-goog