[PATCH] power: supply: ip5xxx: Fix integer overflow in current_now calculation

[PATCH] power: supply: ip5xxx: Fix integer overflow in current_now calculation

[Ondrej Jirman]

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@xff.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

Re: [PATCH] power: supply: ip5xxx: Fix integer overflow in current_now calculation

[Samuel Holland]

On 10/28/22 17:40, Ondrej Jirman wrote:
> 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@xff.cz>

Reviewed-by: Samuel Holland <samuel@sholland.org>

> ---
>  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);

DIV_ROUND_CLOSEST(raw * 149197, 200) would be marginally more accurate,
but it doesn't matter in practice.

>  		return 0;
>  
>  	case POWER_SUPPLY_PROP_CONSTANT_CHARGE_CURRENT:

Re: [PATCH] power: supply: ip5xxx: Fix integer overflow in current_now calculation

[Sebastian Reichel]

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Hi,

On Fri, Oct 28, 2022 at 06:06:07PM -0500, Samuel Holland wrote:
> On 10/28/22 17:40, Ondrej Jirman wrote:
> > 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@xff.cz>
> 
> Reviewed-by: Samuel Holland <samuel@sholland.org>
> 
> > ---
> >  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);
> 
> DIV_ROUND_CLOSEST(raw * 149197, 200) would be marginally more accurate,
> but it doesn't matter in practice.

Thanks, I queued it with that change included.

-- Sebastian

> 
> >  		return 0;
> >  
> >  	case POWER_SUPPLY_PROP_CONSTANT_CHARGE_CURRENT:
> 

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