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

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

[Denis Arefev]

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@vger.kernel.org 
Signed-off-by: Denis Arefev <arefev@swemel.ru>
---
V1 -> V2: 
Added check of the return value it as Ilpo Järvinen <ilpo.jarvinen@linux.intel.com> suggested.
Changed initialization of 'val' variable it as Ilpo Järvinen <ilpo.jarvinen@linux.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

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

[Ilpo Järvinen]

On Thu, 03 Apr 2025 15:26:01 +0300, Denis Arefev wrote:

> 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.
> 
> [...]


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] asus-laptop: Fix an uninitialized variable
      commit: 6c683c6887e4addcd6bd1ddce08cafccb0a21e32

--
 i.