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Date: Wed, 3 Dec 2025 15:12:34 -0800
From: Kees Cook <kees@kernel.org>
To: Joe Perches <joe@perches.com>
Cc: Vlastimil Babka <vbabka@suse.cz>, Andy Whitcroft <apw@canonical.com>,
	Dwaipayan Ray <dwaipayanray1@gmail.com>,
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Subject: Re: [PATCH v5 3/4] checkpatch: Suggest kmalloc_obj family for sizeof
 allocations
Message-ID: <202512031511.ACA8A5DB0@keescook>
References: <20251122014258.do.018-kees@kernel.org>
 <20251122014304.3417954-3-kees@kernel.org>
 <f1d2bb84df85237f23ebf6e0f3dfecfd72d615b6.camel@perches.com>
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In-Reply-To: <f1d2bb84df85237f23ebf6e0f3dfecfd72d615b6.camel@perches.com>

On Fri, Nov 21, 2025 at 08:51:19PM -0800, Joe Perches wrote:
> On Fri, 2025-11-21 at 17:42 -0800, Kees Cook wrote:
> > To support shifting away from sized allocation towards typed
> > allocations, suggest the kmalloc_obj family of macros when a sizeof() is
> > present in the argument lists.
> []
> > diff --git a/scripts/checkpatch.pl b/scripts/checkpatch.pl
> []
> > @@ -7258,17 +7258,42 @@ sub process {
> >  			    "Prefer $3(sizeof(*$1)...) over $3($4...)\n" . $herecurr);
> >  		}
> >  
> > -# check for (kv|k)[mz]alloc with multiplies that could be kmalloc_array/kvmalloc_array/kvcalloc/kcalloc
> > +# check for (kv|k)[mz]alloc that could be kmalloc_obj/kvmalloc_obj/kzalloc_obj/kvzalloc_obj
> 
> There are _way_ too many of these existing uses to suggest this change
> in existing files so please add '&& !$file' to these tests

The goal would be to also do the proposed treewide change which gets
the vast majority of them converted.

-- 
Kees Cook