linux-hardening - Re: [PATCH] lib: introduce simple error-checking wrapper for memparse()

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Message-ID: <aV6ye_vv_0N-SsLu@smile.fi.intel.com>
Date: Wed, 7 Jan 2026 21:22:35 +0200
From: Andy Shevchenko <andriy.shevchenko@...el.com>
To: Dmitry Antipov <dmantipov@...dex.ru>
Cc: Carlos Maiolino <cem@...nel.org>, Christoph Hellwig <hch@...radead.org>,
	Kees Cook <kees@...nel.org>, Andy Shevchenko <andy@...nel.org>,
	Andrew Morton <akpm@...ux-foundation.org>,
	linux-xfs@...r.kernel.org, linux-hardening@...r.kernel.org
Subject: Re: [PATCH] lib: introduce simple error-checking wrapper for
 memparse()

On Wed, Jan 07, 2026 at 09:36:13PM +0300, Dmitry Antipov wrote:
> Introduce 'memvalue()' which uses 'memparse()' to parse a string with
> optional memory suffix into a number and returns this number or ULLONG_MAX
> if the number is negative or an unrecognized character was encountered.

Reading the second patch in the series I do not think this one even needed. The
problem in the original code is that

	int *res, _res;
	...
	*res = _res << something;

This is a UB for _res < 0. So, the code should never handle negative numbers to
begin with. That said the existing memparse() can be used directly.

If I missed something, it's because the commit message here is poorly written
in regard to negative number parsing.

-- 
With Best Regards,
Andy Shevchenko