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: 56f529ce4370 ("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>
---
 drivers/platform/x86/samsung-galaxybook.c | 9 ++++++---
 1 file changed, 6 insertions(+), 3 deletions(-)

diff --git a/drivers/platform/x86/samsung-galaxybook.c b/drivers/platform/x86/samsung-galaxybook.c
index 3c13e13d4885..755cb82bdb60 100644
--- a/drivers/platform/x86/samsung-galaxybook.c
+++ b/drivers/platform/x86/samsung-galaxybook.c
@@ -442,12 +442,13 @@ 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;
 
@@ -455,8 +456,10 @@ static int galaxybook_battery_ext_property_get(struct power_supply *psy,
 	 * 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;
 }
-- 
2.52.0

On Sun, 28 Dec 2025 22:41:31 +0100, Armin Wolf wrote:

> 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.
> 
> [...]


Thank you for your contribution, it has been applied to my local
review-ilpo-fixes branch. Note it will show up in the public
platform-drivers-x86/review-ilpo-fixes branch only once I've pushed my
local branch there, which might take a while.

The list of commits applied:
[1/1] platform/x86: samsung-galaxybook: Fix problematic pointer cast
      commit: d37cd54ebeac37a763fbf303ed25f8a6e98328ff

--
 i.