[PATCH] efi_driver: fix a wrong cast

[Heinrich Schuchardt]

On 9/27/21 6:30 AM, AKASHI Takahiro wrote:
> struct efi_driver_binding_protocol, i.e. bp, is not the first element
> in struct efi_driver_binding_extended_protocol.
> So the casting:
> 	struct efi_driver_binding_extended_protocol *bp =
> 		(struct efi_driver_binding_extended_protocol *)this;
> is simply wrong.

The definition in include/efi_driver.h is:

/*
  * This structure adds internal fields to the driver binding protocol.
  */
struct efi_driver_binding_extended_protocol {
         struct efi_driver_binding_protocol bp;
         const struct efi_driver_ops *ops;
};

Why do you claim "bp is not the first element"?

The whole efi_driver code relies on the fact that the
efi_driver_binding_extended_protocol can be interpreted as
efi_driver_binding_protocol.

Best regards

Heinrich

>
> Signed-off-by: AKASHI Takahiro <takahiro.akashi at linaro.org>
> ---
>   lib/efi_driver/efi_uclass.c | 14 +++++++-------
>   1 file changed, 7 insertions(+), 7 deletions(-)
>
> diff --git a/lib/efi_driver/efi_uclass.c b/lib/efi_driver/efi_uclass.c
> index 382c2b477f4d..9e784f9c237f 100644
> --- a/lib/efi_driver/efi_uclass.c
> +++ b/lib/efi_driver/efi_uclass.c
> @@ -65,8 +65,8 @@ static efi_status_t EFIAPI efi_uc_supported(
>   {
>   	efi_status_t r, ret;
>   	void *interface;
> -	struct efi_driver_binding_extended_protocol *bp =
> -			(struct efi_driver_binding_extended_protocol *)this;
> +	struct efi_driver_binding_extended_protocol *bp = container_of(this,
> +			struct efi_driver_binding_extended_protocol, bp);
>
>   	EFI_ENTRY("%p, %p, %ls", this, controller_handle,
>   		  efi_dp_str(remaining_device_path));
> @@ -113,8 +113,8 @@ static efi_status_t EFIAPI efi_uc_start(
>   {
>   	efi_status_t r, ret;
>   	void *interface = NULL;
> -	struct efi_driver_binding_extended_protocol *bp =
> -			(struct efi_driver_binding_extended_protocol *)this;
> +	struct efi_driver_binding_extended_protocol *bp = container_of(this,
> +			struct efi_driver_binding_extended_protocol, bp);
>
>   	EFI_ENTRY("%p, %p, %ls", this, controller_handle,
>   		  efi_dp_str(remaining_device_path));
> @@ -201,8 +201,8 @@ static efi_status_t EFIAPI efi_uc_stop(
>   	efi_status_t ret;
>   	efi_uintn_t count;
>   	struct efi_open_protocol_info_entry *entry_buffer;
> -	struct efi_driver_binding_extended_protocol *bp =
> -			(struct efi_driver_binding_extended_protocol *)this;
> +	struct efi_driver_binding_extended_protocol *bp = container_of(this,
> +			struct efi_driver_binding_extended_protocol, bp);
>
>   	EFI_ENTRY("%p, %p, %zu, %p", this, controller_handle,
>   		  number_of_children, child_handle_buffer);
> @@ -283,7 +283,7 @@ static efi_status_t efi_add_driver(struct driver *drv)
>   	}
>   	bp->bp.image_handle = bp->bp.driver_binding_handle;
>   	ret = efi_add_protocol(bp->bp.driver_binding_handle,
> -			       &efi_guid_driver_binding_protocol, bp);
> +			       &efi_guid_driver_binding_protocol, &bp->bp);
>   	if (ret != EFI_SUCCESS) {
>   		efi_delete_handle(bp->bp.driver_binding_handle);
>   		free(bp);
>