[PATCH] nvmem: core: Add const to pattrs allocation type

[PATCH] nvmem: core: Add const to pattrs allocation type

[Kees Cook]

From: Kees Cook <kees+treewide@kernel.org>

In preparation for making the devm_kmalloc family of allocators type
aware, we need to make sure that the returned type from the allocation
matches the type of the variable being assigned. (Before, the allocator
would always return "void *", which can be implicitly cast to any
pointer type.)

The assigned type is "const struct bin_attribute **", but the converted
allocation type would be "struct bin_attribute **", which is the same
type without the const qualifier. As there is no general way to safely
add const qualifiers, take the size from the assignment target instead.
No change in allocation size results.

Build tested ARCH=x86_64 allmodconfig with GCC 16.2.0:
drivers/nvmem/core.o

Assisted-by: LLM coccinelle
Signed-off-by: Kees Cook <kees+treewide@kernel.org>
---
Cc: Srinivas Kandagatla <srini@kernel.org>
---
 drivers/nvmem/core.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/nvmem/core.c b/drivers/nvmem/core.c
index 0556d140170a..19edc9ab0282 100644
--- a/drivers/nvmem/core.c
+++ b/drivers/nvmem/core.c
@@ -485,7 +485,7 @@ static int nvmem_populate_sysfs_cells(struct nvmem_device *nvmem)
 	/* Allocate an array of attributes with a sentinel */
 	ncells = list_count_nodes(&nvmem->cells);
 	pattrs = devm_kcalloc(&nvmem->dev, ncells + 1,
-			      sizeof(struct bin_attribute *), GFP_KERNEL);
+			      sizeof(*pattrs), GFP_KERNEL);
 	if (!pattrs)
 		return -ENOMEM;
 
-- 
2.34.1

Re: [PATCH] nvmem: core: Add const to pattrs allocation type

[Srinivas Kandagatla]

On 9/17/26 10:14 PM, Kees Cook wrote:
> From: Kees Cook <kees+treewide@kernel.org>
> 
> In preparation for making the devm_kmalloc family of allocators type
> aware, we need to make sure that the returned type from the allocation
> matches the type of the variable being assigned. (Before, the allocator
> would always return "void *", which can be implicitly cast to any
> pointer type.)
> 
> The assigned type is "const struct bin_attribute **", but the converted
> allocation type would be "struct bin_attribute **", which is the same
> type without the const qualifier. As there is no general way to safely
> add const qualifiers, take the size from the assignment target instead.
> No change in allocation size results.
> 
> Build tested ARCH=x86_64 allmodconfig with GCC 16.2.0:
> drivers/nvmem/core.o
> 
> Assisted-by: LLM coccinelle
> Signed-off-by: Kees Cook <kees+treewide@kernel.org>
> ---
> Cc: Srinivas Kandagatla <srini@kernel.org>
> ---
>  drivers/nvmem/core.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/drivers/nvmem/core.c b/drivers/nvmem/core.c
> index 0556d140170a..19edc9ab0282 100644
> --- a/drivers/nvmem/core.c
> +++ b/drivers/nvmem/core.c
> @@ -485,7 +485,7 @@ static int nvmem_populate_sysfs_cells(struct nvmem_device *nvmem)
>  	/* Allocate an array of attributes with a sentinel */
>  	ncells = list_count_nodes(&nvmem->cells);
>  	pattrs = devm_kcalloc(&nvmem->dev, ncells + 1,
> -			      sizeof(struct bin_attribute *), GFP_KERNEL);
> +			      sizeof(*pattrs), GFP_KERNEL);

Thanks for the patch, while you are at it, there are few more instances
just below this.

--srini
>  	if (!pattrs)
>  		return -ENOMEM;
>  

Re: [PATCH] nvmem: core: Add const to pattrs allocation type

[Kees Cook]

On Thu, Sep 17, 2026 at 10:32:15PM +0100, Srinivas Kandagatla wrote:
> 
> 
> On 9/17/26 10:14 PM, Kees Cook wrote:
> > From: Kees Cook <kees+treewide@kernel.org>
> > 
> > In preparation for making the devm_kmalloc family of allocators type
> > aware, we need to make sure that the returned type from the allocation
> > matches the type of the variable being assigned. (Before, the allocator
> > would always return "void *", which can be implicitly cast to any
> > pointer type.)
> > 
> > The assigned type is "const struct bin_attribute **", but the converted
> > allocation type would be "struct bin_attribute **", which is the same
> > type without the const qualifier. As there is no general way to safely
> > add const qualifiers, take the size from the assignment target instead.
> > No change in allocation size results.
> > 
> > Build tested ARCH=x86_64 allmodconfig with GCC 16.2.0:
> > drivers/nvmem/core.o
> > 
> > Assisted-by: LLM coccinelle
> > Signed-off-by: Kees Cook <kees+treewide@kernel.org>
> > ---
> > Cc: Srinivas Kandagatla <srini@kernel.org>
> > ---
> >  drivers/nvmem/core.c | 2 +-
> >  1 file changed, 1 insertion(+), 1 deletion(-)
> > 
> > diff --git a/drivers/nvmem/core.c b/drivers/nvmem/core.c
> > index 0556d140170a..19edc9ab0282 100644
> > --- a/drivers/nvmem/core.c
> > +++ b/drivers/nvmem/core.c
> > @@ -485,7 +485,7 @@ static int nvmem_populate_sysfs_cells(struct nvmem_device *nvmem)
> >  	/* Allocate an array of attributes with a sentinel */
> >  	ncells = list_count_nodes(&nvmem->cells);
> >  	pattrs = devm_kcalloc(&nvmem->dev, ncells + 1,
> > -			      sizeof(struct bin_attribute *), GFP_KERNEL);
> > +			      sizeof(*pattrs), GFP_KERNEL);
> 
> Thanks for the patch, while you are at it, there are few more instances
> just below this.

There are, but there were no type mismatches with those. pattrs is const,
but attrs and attrs[i].attr.name aren't, so no change is needed there.
Do you want me to flip the attrs devm_kcalloc sizeof to *attrs to much
style, though?

-Kees

-- 
Kees Cook