linux-kernel - Re: [PATCH v6 2/8] iio: core: add fixed point parsing with 64-bit parts

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Message-ID: <7tiv33i65unu5ypk7puj3buzybykyhv2qbwp54bhcem5t4rawq@dpfedqmmxbhx>
Date: Wed, 4 Feb 2026 09:42:55 +0000
From: Rodrigo Alencar <455.rodrigo.alencar@...il.com>
To: Andy Shevchenko <andriy.shevchenko@...el.com>, 
	rodrigo.alencar@...log.com
Cc: linux-kernel@...r.kernel.org, linux-iio@...r.kernel.org, 
	devicetree@...r.kernel.org, linux-doc@...r.kernel.org, Jonathan Cameron <jic23@...nel.org>, 
	David Lechner <dlechner@...libre.com>, Andy Shevchenko <andy@...nel.org>, 
	Lars-Peter Clausen <lars@...afoo.de>, Michael Hennerich <Michael.Hennerich@...log.com>, 
	Rob Herring <robh@...nel.org>, Krzysztof Kozlowski <krzk+dt@...nel.org>, 
	Conor Dooley <conor+dt@...nel.org>, Jonathan Corbet <corbet@....net>
Subject: Re: [PATCH v6 2/8] iio: core: add fixed point parsing with 64-bit
 parts

On 26/02/04 03:45AM, Andy Shevchenko wrote:
> On Fri, Jan 30, 2026 at 10:06:43AM +0000, Rodrigo Alencar via B4 Relay wrote:
> 
> > Add iio_str_to_fixpoint64() function that leverages simple_strtoull()
> > to parse numbers from a string.
> > A helper function __iio_str_to_fixpoint64() replaces
> > __iio_str_to_fixpoint() implementation, extending its usage for
> > 64-bit fixed-point parsing.

...
> > +static ssize_t iio_safe_strntou64(const char *str, const char **endp,
> > +				  u64 *result, size_t max_chars)
> > +{
> > +	u64 digit, acc = 0;
> > +	ssize_t idx = 0;
> > +
> > +	while (isdigit(str[idx]) && idx < max_chars) {
> > +		digit = str[idx] - '0';
> > +		if (unlikely(acc & (~0ull << 60))) {
> > +			if (check_mul_overflow(acc, 10, &acc) ||
> > +			    check_add_overflow(acc, digit, &acc))
> > +				return -ERANGE;
> > +		} else {
> > +			acc = acc * 10 + digit;
> > +		}
> > +		idx++;
> > +	}
> > +
> > +	*endp = str + idx;
> > +	*result = acc;
> > +	return idx;
> > +}
> 
> There is a development in the parse_integer in the lib/. I reviewed that series
> and hopefully it will go in. With that done, we better reuse the lib/ function.
> 
> https://lore.kernel.org/linux-hardening/20260202115451.290173-1-dmantipov@yandex.ru/

In this patch, I see that it updates the overflow check, but I am not
seeing that function being exposed to other kernel modules.

-- 
Kind regards,

Rodrigo Alencar