Re: [PATCH v3 1/3] selftests/mm/write_to_hugetlbfs: parse -s as size_t

Li Wang
2025-12-22T01:46:03Z

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On Mon, Dec 22, 2025 at 6:11 AM David Laight <david.laight.linux@gmail.com>
wrote:

> On Sun, 21 Dec 2025 20:26:37 +0800
> Li Wang <liwang@redhat.com> wrote:
>
> > write_to_hugetlbfs currently parses the -s size argument with atoi()
> > into an int. This silently accepts malformed input, cannot report
> overflow,
> > and can truncate large sizes.
>
> And sscanf() will just ignore invalid trailing characters.
> Probably much the same as atoi() apart from a leading '-'.
>
> Maybe you could use "%zu%c" and check the count is 1 - but I bet
> some static checker won't like that.
>

Yes, that would be stronger, since it would reject trailing garbage.
But for a selftest this is probably sufficient: switching to size_t and
parsing with "%zu" already avoids the int truncation issue.

@Andrew Morton <akpm@linux-foundation.org>,

Hi Andrew, I noticed you have addedthe patches to your mm-new branch,
Let me know if you prefer the "%zu%c" enhancement in a new version.

--
Regards,
Li Wang

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