Re: [PATCH] iio: imu: st_lsm6dsx: Allocate ext_channels with ARRAY_SIZE()

[Lorenzo Bianconi <lorenzo@kernel.org>]

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> 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.)
> 
> This is allocating a copy of magn_channels, which is an array of struct
> iio_chan_spec, but the size was taken from the whole array, which would
> make the allocation type a pointer to the array rather than the
> "struct iio_chan_spec *" being assigned. Allocate ARRAY_SIZE-many
> entries instead. The resulting allocation size is the same.
> 
> Build tested ARCH=x86_64 allmodconfig with GCC 16.2.0:
> drivers/iio/imu/st_lsm6dsx/st_lsm6dsx_shub.o
> 
> Assisted-by: LLM coccinelle
> Signed-off-by: Kees Cook <kees+treewide@kernel.org>

Acked-by: Lorenzo Bianconi <lorenzo@kernel.org>

> ---
> Cc: Lorenzo Bianconi <lorenzo@kernel.org>
> Cc: Jonathan Cameron <jic23@kernel.org>
> Cc: David Lechner <dlechner@baylibre.com>
> Cc: "Nuno Sá" <nuno.sa@analog.com>
> Cc: Andy Shevchenko <andy@kernel.org>
> Cc: <linux-iio@vger.kernel.org>
> ---
>  drivers/iio/imu/st_lsm6dsx/st_lsm6dsx_shub.c | 4 ++--
>  1 file changed, 2 insertions(+), 2 deletions(-)
> 
> diff --git a/drivers/iio/imu/st_lsm6dsx/st_lsm6dsx_shub.c b/drivers/iio/imu/st_lsm6dsx/st_lsm6dsx_shub.c
> index d6a1eeb151ca..cbc47fa5b101 100644
> --- a/drivers/iio/imu/st_lsm6dsx/st_lsm6dsx_shub.c
> +++ b/drivers/iio/imu/st_lsm6dsx/st_lsm6dsx_shub.c
> @@ -766,8 +766,8 @@ st_lsm6dsx_shub_alloc_iiodev(struct st_lsm6dsx_hw *hw,
>  			IIO_CHAN_SOFT_TIMESTAMP(3),
>  		};
>  
> -		ext_channels = devm_kzalloc(hw->dev, sizeof(magn_channels),
> -					    GFP_KERNEL);
> +		ext_channels = devm_kcalloc(hw->dev, ARRAY_SIZE(magn_channels),
> +					    sizeof(*ext_channels), GFP_KERNEL);
>  		if (!ext_channels)
>  			return NULL;
>  
> -- 
> 2.34.1
> 

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