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b=k5mcq+9jHOWQHwCsIwdPytzf22xUG1PXgxXrh1jZEGbut8FBQSnZffk41jdeNMa9r RxCt/YDDTmSJfBMNY6FUuoxqEzsV7QIHEfzVdHXNlRZoxCZ9iZTNvJcTIiuYapadcv FCwvSYs1yjkihMGxMaewrJBiKgzeM5TOMiwZBkYvF9ya+o8JPgNBRQ1J/rI/Tl6Kyy 2tjnysSQ1QaNQvG2ArYo5qapPY1hDURLbBSh0nHrPSahNAswY7MitJ5FZCJ9Xbcnr0 XlCkAbf+6rQCu5UnaqNY/wAVwTOCV0b+Cn0Bz85PBkzDuIf6alj1usL6I/dg6qN4mn ofmO9koIbDOtA== Message-ID: <751a94a7-d5b2-415e-9591-a7d97b452d81@kernel.org> Date: Thu, 26 Feb 2026 11:02:43 +0100 MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH] slab: Saturate to SIZE_MAX for allocation size overflows Content-Language: en-US To: Kees Cook , Matthew Wilcox Cc: Vlastimil Babka , Andrew Morton , Christoph Lameter , David Rientjes , Roman Gushchin , Harry Yoo , linux-mm@kvack.org, linux-kernel@vger.kernel.org, linux-hardening@vger.kernel.org References: <20260225013954.work.319-kees@kernel.org> <202602242315.C9D5430C7@keescook> From: "Vlastimil Babka (SUSE)" In-Reply-To: <202602242315.C9D5430C7@keescook> Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit X-Stat-Signature: wyh3cxonrnsfx1amw8gz7xa95rdgwyqs X-Rspamd-Server: rspam11 X-Rspam-User: X-Rspamd-Queue-Id: 5293FC000B X-HE-Tag: 1772100168-79173 X-HE-Meta: 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 W6FUbqZ4 5IJyRSl/HyXGlq2ILhRmoKkFkQJDXf9q0K7njJy6Z/kYkyEZ7jz5BrwBLIZ/qZdYasWYGzzXhBC+4ICLeClVbF1TFmU4/6KjvAltEPuy2wecxYzTVU6ZLIQCJVXbYK4ME6QEAjfa9uN4P/nr0xB5clCQdvF4zrVOUb81wTvhM2z91hKI99udhahb9pkvqZUOKCXysgct3hM86bznCKNbCCwkdNOHChqNbFWGagnn3IcLzmdTEQlJOxCSjFwwV9lwggJ37xnt0koTZErx2ARAbCOg+lJj3Q9h8GAjDifRF1soDiWvEYovwY8awGQ== Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: On 2/25/26 08:15, Kees Cook wrote: > On Wed, Feb 25, 2026 at 03:59:08AM +0000, Matthew Wilcox wrote: >> On Tue, Feb 24, 2026 at 05:40:02PM -0800, Kees Cook wrote: >> > +++ b/include/linux/slab.h >> > @@ -1105,7 +1105,7 @@ static inline __alloc_size(1, 2) void *kmalloc_array_noprof(size_t n, size_t siz >> > size_t bytes; >> > >> > if (unlikely(check_mul_overflow(n, size, &bytes))) >> > - return NULL; >> > + bytes = SIZE_MAX; >> > return kmalloc_noprof(bytes, flags); >> >> Wouldn't this be better written as: >> >> return kmalloc_noprof(size_mul(n, size), flags); >> >> (etc) > > Sure, I can convert them all that way if that's preferred? Yeah I think it's better than effectively open-code the same thing?