linux-kernel - Re: [PATCH] iio: adc: ad_sigma_delta: Fix use of uninitialized variable status

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Message-ID: <c3ad805b-4ccf-4218-8b81-66a8977e2928@gmail.com>
Date: Thu, 10 Apr 2025 22:28:20 +0530
From: Purva Yeshi <purvayeshi550@...il.com>
To: Nuno Sá <noname.nuno@...il.com>, lars@...afoo.de,
 Michael.Hennerich@...log.com, jic23@...nel.org
Cc: linux-iio@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH] iio: adc: ad_sigma_delta: Fix use of uninitialized
 variable status_pos

On 10/04/25 16:39, Nuno Sá wrote:
> Hi Purva,
> 
> Thanks for your patch... See below
> On Thu, 2025-04-10 at 01:31 +0530, Purva Yeshi wrote:
>> Fix Smatch-detected error:
>> drivers/iio/adc/ad_sigma_delta.c:604 ad_sd_trigger_handler() error:
>> uninitialized symbol 'status_pos'.
>>
>> The variable `status_pos` was only initialized in specific switch cases
>> (1, 2, 3, 4), which could leave it uninitialized if `reg_size` had an
>> unexpected value.
>>
>> Fix by validating `reg_size` before the switch block. If it’s not
>> one of the expected values, return early and log an error. This ensures
>> `status_pos` is always initialized before use and prevents undefined
>> behavior.
>>
>> Signed-off-by: Purva Yeshi <purvayeshi550@...il.com>
>> ---
>>   drivers/iio/adc/ad_sigma_delta.c | 5 +++++
>>   1 file changed, 5 insertions(+)
>>
>> diff --git a/drivers/iio/adc/ad_sigma_delta.c
>> b/drivers/iio/adc/ad_sigma_delta.c
>> index 6c37f8e21120..d3b59d90b728 100644
>> --- a/drivers/iio/adc/ad_sigma_delta.c
>> +++ b/drivers/iio/adc/ad_sigma_delta.c
>> @@ -568,6 +568,11 @@ static irqreturn_t ad_sd_trigger_handler(int irq, void
>> *p)
>>   	else
>>   		transfer_size = reg_size;
>>   
>> +	if (reg_size != 1 && reg_size != 2 && reg_size != 3 && reg_size != 4)
>> {
>> +		dev_err(&indio_dev->dev, "Unsupported reg_size: %u\n",
>> reg_size);
>> +		return IRQ_HANDLED;
>> +	}
>> +
> 
> Use the switch case for this. Add a default branch for the invalid case. You
> should also use dev_err_ratelimited() and instead of 'return IRQ_HANDLED', do
> 'goto irq_handled'.
> 
> Thx!
> - Nuno Sá

Hi Nuno,

Thank you for the review and guidance.

I’ve updated the patch to address your suggestions and will send the 
next version shortly.

Best regards,
Purva

> 
>>   	switch (reg_size) {
>>   	case 4:
>>   	case 2: