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Message-ID: <751a94a7-d5b2-415e-9591-a7d97b452d81@kernel.org>
Date: Thu, 26 Feb 2026 11:02:43 +0100
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Subject: Re: [PATCH] slab: Saturate to SIZE_MAX for allocation size overflows
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To: Kees Cook <kees@kernel.org>, Matthew Wilcox <willy@infradead.org>
Cc: Vlastimil Babka <vbabka@suse.cz>,
 Andrew Morton <akpm@linux-foundation.org>, Christoph Lameter
 <cl@gentwo.org>, David Rientjes <rientjes@google.com>,
 Roman Gushchin <roman.gushchin@linux.dev>, Harry Yoo <harry.yoo@oracle.com>,
 linux-mm@kvack.org, linux-kernel@vger.kernel.org,
 linux-hardening@vger.kernel.org
References: <20260225013954.work.319-kees@kernel.org>
 <aZ5zjIpYZYoc-LSX@casper.infradead.org> <202602242315.C9D5430C7@keescook>
From: "Vlastimil Babka (SUSE)" <vbabka@kernel.org>
In-Reply-To: <202602242315.C9D5430C7@keescook>
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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?