[PATCH AUTOSEL 6.1 02/33] power: supply: sc27xx: Fix external_power_changed race

From: Sasha Levin
Date: Wed May 31 2023 - 09:45:14 EST

From: Hans de Goede <hdegoede@xxxxxxxxxx>

[ Upstream commit 4d5c129d6c8993fe96e9ae712141eedcb9ca68c2 ]

sc27xx_fgu_external_power_changed() dereferences data->battery,
which gets sets in ab8500_btemp_probe() like this:

data->battery = devm_power_supply_register(dev, &sc27xx_fgu_desc,

As soon as devm_power_supply_register() has called device_add()
the external_power_changed callback can get called. So there is a window
where sc27xx_fgu_external_power_changed() may get called while
data->battery has not been set yet leading to a NULL pointer dereference.

Fixing this is easy. The external_power_changed callback gets passed
the power_supply which will eventually get stored in data->battery,
so sc27xx_fgu_external_power_changed() can simply directly use
the passed in psy argument which is always valid.

After this change sc27xx_fgu_external_power_changed() is reduced to just
"power_supply_changed(psy);" and it has the same prototype. While at it
simply replace it with making the external_power_changed callback
directly point to power_supply_changed.

Cc: Orson Zhai <orsonzhai@xxxxxxxxx>
Cc: Chunyan Zhang <zhang.lyra@xxxxxxxxx>
Signed-off-by: Hans de Goede <hdegoede@xxxxxxxxxx>
Reviewed-by: Baolin Wang <baolin.wang@xxxxxxxxxxxxxxxxx>
Signed-off-by: Sebastian Reichel <sebastian.reichel@xxxxxxxxxxxxx>
Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx>
drivers/power/supply/sc27xx_fuel_gauge.c | 9 +--------
1 file changed, 1 insertion(+), 8 deletions(-)

diff --git a/drivers/power/supply/sc27xx_fuel_gauge.c b/drivers/power/supply/sc27xx_fuel_gauge.c
index 632977f84b954..bd23c4d9fed43 100644
--- a/drivers/power/supply/sc27xx_fuel_gauge.c
+++ b/drivers/power/supply/sc27xx_fuel_gauge.c
@@ -733,13 +733,6 @@ static int sc27xx_fgu_set_property(struct power_supply *psy,
return ret;

-static void sc27xx_fgu_external_power_changed(struct power_supply *psy)
- struct sc27xx_fgu_data *data = power_supply_get_drvdata(psy);
- power_supply_changed(data->battery);
static int sc27xx_fgu_property_is_writeable(struct power_supply *psy,
enum power_supply_property psp)
@@ -774,7 +767,7 @@ static const struct power_supply_desc sc27xx_fgu_desc = {
.num_properties = ARRAY_SIZE(sc27xx_fgu_props),
.get_property = sc27xx_fgu_get_property,
.set_property = sc27xx_fgu_set_property,
- .external_power_changed = sc27xx_fgu_external_power_changed,
+ .external_power_changed = power_supply_changed,
.property_is_writeable = sc27xx_fgu_property_is_writeable,
.no_thermal = true,