power: supply: axp288_fuel_gauge: Fix external_power_changed race

commit f8319774d6f1567d6e7d03653174ab0c82c5c66d upstream.

fuel_gauge_external_power_changed() dereferences info->bat,
which gets sets in axp288_fuel_gauge_probe() like this:

  info->bat = devm_power_supply_register(dev, &fuel_gauge_desc, &psy_cfg);

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 fuel_gauge_external_power_changed() may get called while
info->bat 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 info->bat,
so fuel_gauge_external_power_changed() can simply directly use
the passed in psy argument which is always valid.

Fixes: 21156063f422 ("power: supply: axp288_fuel_gauge: Take lock before updating the valid flag")
Cc: stable@vger.kernel.org
Signed-off-by: Hans de Goede <hdegoede@redhat.com>
Signed-off-by: Sebastian Reichel <sebastian.reichel@collabora.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

diff --git a/drivers/power/supply/axp288_fuel_gauge.c b/drivers/power/supply/axp288_fuel_gauge.c
index 05f41317846296b067f41d050abc66d26cf09ff0..3be6f3b10ea4286e218f876798a0c7f0b99e4aa0 100644 (file)
--- a/drivers/power/supply/axp288_fuel_gauge.c
+++ b/drivers/power/supply/axp288_fuel_gauge.c
@@ -507,7 +507,7 @@ static void fuel_gauge_external_power_changed(struct power_supply *psy)
        mutex_lock(&info->lock);
        info->valid = 0; /* Force updating of the cached registers */
        mutex_unlock(&info->lock);
-       power_supply_changed(info->bat);
+       power_supply_changed(psy);
 }
 
 static struct power_supply_desc fuel_gauge_desc = {