linux-kernel - Re: [PATCH v5 1/5] lib: fix _parse_integer

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Message-ID: <aYWbcFb73qO16tEC@smile.fi.intel.com>
Date: Fri, 6 Feb 2026 09:42:40 +0200
From: Andy Shevchenko <andriy.shevchenko@...el.com>
To: David Laight <david.laight.linux@...il.com>
Cc: Dmitry Antipov <dmantipov@...dex.ru>,
	Andrew Morton <akpm@...ux-foundation.org>,
	Kees Cook <kees@...nel.org>, "Darrick J . Wong" <djwong@...nel.org>,
	linux-hardening@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH v5 1/5] lib: fix _parse_integer_limit() to handle overflow

On Thu, Feb 05, 2026 at 10:15:37PM +0000, David Laight wrote:
> On Wed,  4 Feb 2026 16:57:13 +0300
> Dmitry Antipov <dmantipov@...dex.ru> wrote:

...

> Although I wonder whether strtoul() (etc) should stop 'eating' input
> when the value would overflow

Definitely no stop condition. The idea behind simple_strto*() in the kernel
is that they will help to parse combined strings (several fields in one
*constant* string), not eating the extra "valid" characters (digits) will
be a disaster in a couple of aspects.

> and return a pointer to the digit that caused the error.

No.

> Code looking at the terminating character wont be expecting a digit
> and will treat it as a syntax error - which is what you are trying to do.
> 
> That is a much easier API to use, and a 'drop-in' for existing code.

Maybe, but problematic from the usage point of view as I described above.

-- 
With Best Regards,
Andy Shevchenko