platform/x86: samsung-galaxybook: Fix problematic pointer cast

A user reported that reading the charge threshold on his device
results in very strange values (like 78497792) being returned.
The reason for this seems to be the fact that the driver casts
the int pointer to an u8 pointer, leaving the last 3 bytes of
the destination uninitialized. Fix this by using a temporary
variable instead.

Cc: stable@vger.kernel.org
Fixes: 56f529c ("platform/x86: samsung-galaxybook: Add samsung-galaxybook driver")
Reported-by: Gianni Ceccarelli <dakkar@thenautilus.net>
Closes: https://lore.kernel.org/platform-driver-x86/20251228115556.14362d66@thenautilus.net/
Tested-by: Gianni Ceccarelli <dakkar@thenautilus.net>
Signed-off-by: Armin Wolf <W_Armin@gmx.de>
Link: https://patch.msgid.link/20251228214217.35972-1-W_Armin@gmx.de
Reviewed-by: Ilpo Järvinen <ilpo.jarvinen@linux.intel.com>
Signed-off-by: Ilpo Järvinen <ilpo.jarvinen@linux.intel.com>

Author: Wer-Wolf

drivers/platform/x86/samsung-galaxybook.c

@@ -442,21 +442,24 @@ static int galaxybook_battery_ext_property_get(struct power_supply *psy,
 					       union power_supply_propval *val)
 {
 	struct samsung_galaxybook *galaxybook = ext_data;
+	u8 value;
 	int err;
 
 	if (psp != POWER_SUPPLY_PROP_CHARGE_CONTROL_END_THRESHOLD)
 		return -EINVAL;
 
-	err = charge_control_end_threshold_acpi_get(galaxybook, (u8 *)&val->intval);
+	err = charge_control_end_threshold_acpi_get(galaxybook, &value);
 	if (err)
 		return err;
 
 	/*
 	 * device stores "no end threshold" as 0 instead of 100;
 	 * if device has 0, report 100
 	 */
-	if (val->intval == 0)
-		val->intval = 100;
+	if (value == 0)
+		value = 100;
+
+	val->intval = value;
 
 	return 0;
 }