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AJvYcCVkqrGg968Tg0+flPHukocs3y5IvrJ821Cc7Av6oF9/LfcxqO4qm0nilf+Kcx+kA0rcvZlnSiIPVw==@kvack.org X-Gm-Message-State: AOJu0YyCKNtOboW8/pg690oepT97SVkr6DldquuN4H3RZs5kwaFEGIQ6 6mfzq4wb3ERTTsESRvqObzQDVTdqX+97GA1QeOkEt/TG5wiPctso0WFXn5YPJhzNd6G0A4nKZm6 tG8r+2pPw5YKOLcTGIm4S8JAEePF6O/SxK5GbpXJcoa0KwdKOBAFbqfWypa0hUC4KKaVhyVWJWk k0anXDLMMVnntU4HIhhfDvK86U2sw= X-Gm-Gg: AY/fxX4iqF5I6NAkcvuPSGJe7mCfK8ehihQoQ6CVx3tnu8Dt5kGbqYDFEG7JlRuIUJK EDcooHQZSFmlS6q7HLMIVh3/kWVQyHCIZKpHwl35XWa9THvwrHhHKoW0bC1iNk3VgEIZpx2IJuG 8tnGR6FAHcg35AlPR5etXTxrNfrruewjOdVqhhP8JbGhZtD7KPxG/xjlBCUrAdJhD5AHU= X-Received: by 2002:a05:7301:508a:b0:2af:7429:e53d with SMTP id 5a478bee46e88-2b05ebf88e5mr5345519eec.10.1766367954083; Sun, 21 Dec 2025 17:45:54 -0800 (PST) X-Google-Smtp-Source: AGHT+IHCBWqVsapONNRea9BKHJV2jQFdLFXvNDn5VCkIegnUhkljoDAAO5m9Ok/mlEnNrihMaJ3hNHw9Ky3TbfJ6MN4= X-Received: by 2002:a05:7301:508a:b0:2af:7429:e53d with SMTP id 5a478bee46e88-2b05ebf88e5mr5345502eec.10.1766367953670; Sun, 21 Dec 2025 17:45:53 -0800 (PST) MIME-Version: 1.0 References: <20251221122639.3168038-1-liwang@redhat.com> <20251221122639.3168038-2-liwang@redhat.com> <20251221221052.3b769fc2@pumpkin> In-Reply-To: <20251221221052.3b769fc2@pumpkin> From: Li Wang Date: Mon, 22 Dec 2025 09:45:41 +0800 X-Gm-Features: AQt7F2q3Gord7vebrD32dnNAsR5HLmi3eY2E6lC71d3Zho6nx9lidqAeoSL3tfY Message-ID: Subject: Re: [PATCH v3 1/3] selftests/mm/write_to_hugetlbfs: parse -s as size_t To: David Laight Cc: akpm@linux-foundation.org, linux-kselftest@vger.kernel.org, linux-kernel@vger.kernel.org, linux-mm@kvack.org, David Hildenbrand , Mark Brown , Shuah Khan , Waiman Long X-Mimecast-Spam-Score: 0 X-Mimecast-MFC-PROC-ID: 3zF5xufeZ5QUyOMTFOFhQ4LtRJQZ8ja1vU4VVt9D6r0_1766367954 X-Mimecast-Originator: redhat.com Content-Type: multipart/alternative; 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charset="UTF-8" Content-Transfer-Encoding: quoted-printable On Mon, Dec 22, 2025 at 6:11=E2=80=AFAM David Laight wrote: > On Sun, 21 Dec 2025 20:26:37 +0800 > Li Wang 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 , 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. --=20 Regards, Li Wang --0000000000006beb3e06468096ae Content-Type: text/html; charset="UTF-8" Content-Transfer-Encoding: quoted-printable


On Mon, Dec 22, 2025 at 6:11= =E2=80=AFAM David Laight <david.laight.linux@gmail.com> wrote:
On Sun, 21 Dec 2025 20:26:37 +0800
Li Wang <liwang@r= edhat.com> wrote:

> write_to_hugetlbfs currently parses the -s size argument with atoi() > into an int. This silently accepts malformed input, cannot report over= flow,
> 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<= br> some static checker won't like that.

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


Hi Andrew, I noticed you have addedthe patches to your mm-new branch,
Let me know if you prefer the=C2=A0&quo= t;%zu%c"=C2=A0= enhancement in a new version.


--
Regards,
Li Wang
--0000000000006beb3e06468096ae--