linux-kernel - [PATCH v2] asus-laptop: Fix an uninitialized variable

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Message-ID: <20250403122603.18172-1-arefev@swemel.ru>
Date: Thu,  3 Apr 2025 15:26:01 +0300
From: Denis Arefev <arefev@...mel.ru>
To: Corentin Chary <corentin.chary@...il.com>
Cc: "Luke D. Jones" <luke@...nes.dev>,
	Hans de Goede <hdegoede@...hat.com>,
	Ilpo Järvinen <ilpo.jarvinen@...ux.intel.com>,
	platform-driver-x86@...r.kernel.org,
	linux-kernel@...r.kernel.org,
	lvc-project@...uxtesting.org,
	stable@...r.kernel.org
Subject: [PATCH v2] asus-laptop: Fix an uninitialized variable

The value returned by acpi_evaluate_integer() is not checked,
but the result is not always successful, so it is necessary to
add a check of the returned value.

If the result remains negative during three iterations of the loop,
then the uninitialized variable 'val' will be used in the clamp_val()
macro, so it must be initialized with the current value of the 'curr'
variable.

In this case, the algorithm should be less noisy.

Found by Linux Verification Center (linuxtesting.org) with SVACE.

Fixes: b23910c2194e ("asus-laptop: Pegatron Lucid accelerometer")
Cc: stable@...r.kernel.org 
Signed-off-by: Denis Arefev <arefev@...mel.ru>
---
V1 -> V2: 
Added check of the return value it as Ilpo Järvinen <ilpo.jarvinen@...ux.intel.com> suggested.
Changed initialization of 'val' variable it as Ilpo Järvinen <ilpo.jarvinen@...ux.intel.com> suggested.

 drivers/platform/x86/asus-laptop.c | 8 +++++---
 1 file changed, 5 insertions(+), 3 deletions(-)

diff --git a/drivers/platform/x86/asus-laptop.c b/drivers/platform/x86/asus-laptop.c
index d460dd194f19..ff674c6d0bbb 100644
--- a/drivers/platform/x86/asus-laptop.c
+++ b/drivers/platform/x86/asus-laptop.c
@@ -427,10 +427,12 @@ static int asus_pega_lucid_set(struct asus_laptop *asus, int unit, bool enable)
 static int pega_acc_axis(struct asus_laptop *asus, int curr, char *method)
 {
 	int i, delta;
-	unsigned long long val;
+	acpi_status status;
+	unsigned long long val = (unsigned long long)curr;
 	for (i = 0; i < PEGA_ACC_RETRIES; i++) {
-		acpi_evaluate_integer(asus->handle, method, NULL, &val);
-
+		status = acpi_evaluate_integer(asus->handle, method, NULL, &val);
+		if (ACPI_FAILURE(status))
+			continue;
 		/* The output is noisy.  From reading the ASL
 		 * dissassembly, timeout errors are returned with 1's
 		 * in the high word, and the lack of locking around
-- 
2.43.0