linux-kernel - [PATCH] power: supply: ip5xxx: Fix integer overflow in current

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Message-Id: <20221028224052.293693-1-megi@xff.cz>
Date:   Sat, 29 Oct 2022 00:40:52 +0200
From:   Ondrej Jirman <megi@....cz>
To:     linux-rockchip@...ts.infradead.org
Cc:     Ondrej Jirman <megi@....cz>, Samuel Holland <samuel@...lland.org>,
        Sebastian Reichel <sre@...nel.org>,
        linux-pm@...r.kernel.org (open list:POWER SUPPLY CLASS/SUBSYSTEM and
        DRIVERS), linux-kernel@...r.kernel.org (open list)
Subject: [PATCH] power: supply: ip5xxx: Fix integer overflow in current_now calculation

When current is larger than ~2A, the multiplication in current_now
property overflows and the kernel reports invalid negative current
value. Change the numerator and denominator while preserving their
ratio to allow up to +-6A before the overflow.

Fixes: 75853406fa27 ("power: supply: Add a driver for Injoinic power bank ICs")
Signed-off-by: Ondrej Jirman <megi@....cz>
---
 drivers/power/supply/ip5xxx_power.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/power/supply/ip5xxx_power.c b/drivers/power/supply/ip5xxx_power.c
index 02ee4d252a3e..f39cb2f7aa11 100644
--- a/drivers/power/supply/ip5xxx_power.c
+++ b/drivers/power/supply/ip5xxx_power.c
@@ -398,7 +398,7 @@ static int ip5xxx_battery_get_property(struct power_supply *psy,
 		ret = ip5xxx_battery_read_adc(ip5xxx, IP5XXX_BATIADC_DAT0,
 					      IP5XXX_BATIADC_DAT1, &raw);
 
-		val->intval = DIV_ROUND_CLOSEST(raw * 745985, 1000);
+		val->intval = DIV_ROUND_CLOSEST(raw * 261095, 350);
 		return 0;
 
 	case POWER_SUPPLY_PROP_CONSTANT_CHARGE_CURRENT:
-- 
2.38.1