linux-kernel - [PATCH RESEND] twl4030_charger: fix charging current out-of-bounds

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Date:   Mon, 17 Sep 2018 07:20:35 +0200
From:   Andreas Kemnade <andreas@...nade.info>
To:     sre@...nel.org, linux-pm@...r.kernel.org,
        linux-omap@...r.kernel.org,
        Discussions about the Letux Kernel 
        <letux-kernel@...nphoenux.org>, linux-kernel@...r.kernel.org
Cc:     Andreas Kemnade <andreas@...nade.info>
Subject: [PATCH RESEND] twl4030_charger: fix charging current out-of-bounds

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@...nade.info>
---
 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 b72838663872..c954b7234393 100644
--- a/drivers/power/supply/twl4030_charger.c
+++ b/drivers/power/supply/twl4030_charger.c
@@ -421,7 +421,8 @@ 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) {
-- 
2.11.0