Re: [PATCH 7/7] hwmon: it87: Use zero-initialization instead of memset()

[sashiko-bot@kernel.org]

Thank you for your contribution! Sashiko AI review found 1 potential issue(s) to consider:
- [Medium] Replacing memset() with empty brace initialization leaves struct padding bytes uninitialized, causing a KMSAN uninit-value warning when copied via platform_device_add_data().
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commit 429f8b305f54cb034b99374e3bdaa61a1ba8f424
Author: Manish Baing <manishbaing2789@gmail.com>

hwmon: it87: Use zero-initialization instead of memset()

This commit reduces the scope of 'sio_data' by moving it inside the for-loop
and replacing the explicit memset() with empty brace initialization.

> diff --git a/drivers/hwmon/it87.c b/drivers/hwmon/it87.c
> index 5fd310662ee43..f3f8d835ff92a 100644
> --- a/drivers/hwmon/it87.c
> +++ b/drivers/hwmon/it87.c
> @@ -3777,7 +3777,6 @@ MODULE_DEVICE_TABLE(dmi, it87_dmi_table);
>  static int __init sm_it87_init(void)
>  {
>  	int sioaddr[2] = { REG_2E, REG_4E };
> -	struct it87_sio_data sio_data;
>  	unsigned short isa_address[2];
>  	bool found = false;
>  	int i, err;
> @@ -3789,7 +3788,7 @@ static int __init sm_it87_init(void)
>  	dmi_check_system(it87_dmi_table);
>  
>  	for (i = 0; i < ARRAY_SIZE(sioaddr); i++) {
> -		memset(&sio_data, 0, sizeof(struct it87_sio_data));
> +		struct it87_sio_data sio_data = { };

[Severity: Medium]
Does replacing memset() with empty brace initialization leave struct padding
bytes uninitialized?

Empty brace initialization is often lowered by compilers to member-wise
zeroing, which skips padding bytes.

When this structure is passed to it87_device_add(), it is copied
byte-by-byte via platform_device_add_data():

drivers/hwmon/it87.c:it87_device_add() {
	...
	err = platform_device_add_data(pdev, sio_data,
				       sizeof(struct it87_sio_data));
	...
}

Because platform_device_add_data() uses kmemdup() to copy the entire size of
the structure, won't reading the uninitialized padding bytes trigger a KMSAN
uninitialized-value warning during driver probe?

>  		isa_address[i] = 0;
>  		err = it87_find(sioaddr[i], &isa_address[i], &sio_data, i);
>  		if (err || isa_address[i] == 0)

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Sashiko AI review · https://sashiko.dev/#/patchset/20260530221353.159461-1-manishbaing2789@gmail.com?part=7