[PATCH 4.9 088/222] power: supply: twl4030_charger: fix charging current out-of-bounds

[Greg Kroah-Hartman]

From: Andreas Kemnade <andreas@xxxxxxxxxxxx>

[ Upstream commit 8314c212f995bc0d06b54ad02ef0ab4089781540 ]

the charging current uses unsigned int variables, if we step back
if the current is still low, we would run into negative which
means setting the target to a huge value.
Better add checks here.

Signed-off-by: Andreas Kemnade <andreas@xxxxxxxxxxxx>
Signed-off-by: Sebastian Reichel <sebastian.reichel@xxxxxxxxxxxxx>
Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx>
---
 drivers/power/supply/twl4030_charger.c | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/drivers/power/supply/twl4030_charger.c b/drivers/power/supply/twl4030_charger.c
index bcd4dc304f270..14fed11e8f6e3 100644
--- a/drivers/power/supply/twl4030_charger.c
+++ b/drivers/power/supply/twl4030_charger.c
@@ -449,7 +449,8 @@ static void twl4030_current_worker(struct work_struct *data)
 
 	if (v < USB_MIN_VOLT) {
 		/* Back up and stop adjusting. */
-		bci->usb_cur -= USB_CUR_STEP;
+		if (bci->usb_cur >= USB_CUR_STEP)
+			bci->usb_cur -= USB_CUR_STEP;
 		bci->usb_cur_target = bci->usb_cur;
 	} else if (bci->usb_cur >= bci->usb_cur_target ||
 		   bci->usb_cur + USB_CUR_STEP > USB_MAX_CURRENT) {
-- 
2.20.1