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

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Message-ID: <c7f5f4cc-c187-4402-91dd-4d0096e396fa@swemel.ru>
Date: Wed, 26 Mar 2025 15:07:42 +0300
From: Arefev <arefev@...mel.ru>
To: Ilpo Järvinen <ilpo.jarvinen@...ux.intel.com>
Cc: Corentin Chary <corentin.chary@...il.com>, "Luke D. Jones"
 <luke@...nes.dev>, Hans de Goede <hdegoede@...hat.com>,
 platform-driver-x86@...r.kernel.org, linux-kernel@...r.kernel.org,
 lvc-project@...uxtesting.org
Subject: Re: [PATCH] asus-laptop: Fix an uninitialized variable

25.03.2025 14:18, Ilpo Järvinen пишет:
> On Tue, 25 Mar 2025, Denis Arefev wrote:
>
>> The value returned by the acpi_evaluate_integer() function is not
>> checked, but the result is not always successful, so an uninitialized
>> 'val' variable may be used in calculations.
>>
>> 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>
>> ---
>>   drivers/platform/x86/asus-laptop.c | 2 +-
>>   1 file changed, 1 insertion(+), 1 deletion(-)
>>
>> diff --git a/drivers/platform/x86/asus-laptop.c b/drivers/platform/x86/asus-laptop.c
>> index d460dd194f19..b74b7d0eb6c2 100644
>> --- a/drivers/platform/x86/asus-laptop.c
>> +++ b/drivers/platform/x86/asus-laptop.c
>> @@ -427,7 +427,7 @@ 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;
>> +	unsigned long long val = PEGA_ACC_CLAMP;
>>   	for (i = 0; i < PEGA_ACC_RETRIES; i++) {
>>   		acpi_evaluate_integer(asus->handle, method, NULL, &val);
> Shouldn't you handle the error from acpi_evaluate_integer() properly
> instead?
>
Apparently, the developer realized that the output is very noisy and
therefore created an algorithm that will surely return a good result.

I did not check the return value, because if acpi_evaluate_integer()
cannot read the values of accelerometers, 'val' will remain
uninitialized and will be used in further calculations.