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SubjectRe: [PATCH] pinctrl: tb10x: Use flexible-array member and struct_size() helper
On Thu, Jun 06, 2019 at 10:12:32AM -0500, Gustavo A. R. Silva wrote:
> Update the code to use a flexible array member instead of a pointer in
> structure i2c_mux_pinctrl and use the struct_size() helper:
>
> struct tb10x_pinctrl {
> ...
> struct tb10x_of_pinfunc pinfuncs[];
> };
>
> Also, make use of the struct_size() helper instead of an open-coded
> version in order to avoid any potential type mistakes, in particular
> in the context in which this code is being used.
>
> So, replace the following form:
>
> sizeof(struct tb10x_pinctrl) + of_get_child_count(of_node) * sizeof(struct tb10x_of_pinfunc)
>
> with:
>
> struct_size(state, pinfuncs, of_get_child_count(of_node))
>
> This code was detected with the help of Coccinelle.
>
> Signed-off-by: Gustavo A. R. Silva <gustavo@embeddedor.com>

Reviewed-by: Kees Cook <keescook@chromium.org>

-Kees

> ---
> drivers/pinctrl/pinctrl-tb10x.c | 12 +++++-------
> 1 file changed, 5 insertions(+), 7 deletions(-)
>
> diff --git a/drivers/pinctrl/pinctrl-tb10x.c b/drivers/pinctrl/pinctrl-tb10x.c
> index 2e90a6d8fb3b..a32badf3f118 100644
> --- a/drivers/pinctrl/pinctrl-tb10x.c
> +++ b/drivers/pinctrl/pinctrl-tb10x.c
> @@ -483,22 +483,22 @@ struct tb10x_port {
> * @base: register set base address.
> * @pingroups: pointer to an array of the pin groups this driver manages.
> * @pinfuncgrpcnt: number of pingroups in @pingroups.
> - * @pinfuncs: pointer to an array of pin functions this driver manages.
> * @pinfuncnt: number of pin functions in @pinfuncs.
> * @mutex: mutex for exclusive access to a pin controller's state.
> * @ports: current state of each port.
> * @gpios: Indicates if a given pin is currently used as GPIO (1) or not (0).
> + * @pinfuncs: flexible array of pin functions this driver manages.
> */
> struct tb10x_pinctrl {
> struct pinctrl_dev *pctl;
> void *base;
> const struct tb10x_pinfuncgrp *pingroups;
> unsigned int pinfuncgrpcnt;
> - struct tb10x_of_pinfunc *pinfuncs;
> unsigned int pinfuncnt;
> struct mutex mutex;
> struct tb10x_port ports[TB10X_PORTS];
> DECLARE_BITMAP(gpios, MAX_PIN + 1);
> + struct tb10x_of_pinfunc pinfuncs[];
> };
>
> static inline void tb10x_pinctrl_set_config(struct tb10x_pinctrl *state,
> @@ -771,15 +771,13 @@ static int tb10x_pinctrl_probe(struct platform_device *pdev)
> return -EINVAL;
> }
>
> - state = devm_kzalloc(dev, sizeof(struct tb10x_pinctrl) +
> - of_get_child_count(of_node)
> - * sizeof(struct tb10x_of_pinfunc),
> - GFP_KERNEL);
> + state = devm_kzalloc(dev, struct_size(state, pinfuncs,
> + of_get_child_count(of_node)),
> + GFP_KERNEL);
> if (!state)
> return -ENOMEM;
>
> platform_set_drvdata(pdev, state);
> - state->pinfuncs = (struct tb10x_of_pinfunc *)(state + 1);
> mutex_init(&state->mutex);
>
> mem = platform_get_resource(pdev, IORESOURCE_MEM, 0);
> --
> 2.21.0
>

--
Kees Cook

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