Re: [PATCH] efi_loader: Remove incorrect calls of EFI_CALL in TCG2

[AKASHI Takahiro <takahiro.akashi@linaro.org>]

Heinrich,

On Thu, Sep 09, 2021 at 12:30:49AM +0300, Ilias Apalodimas wrote:
> There is two unneeded EFI_CALL references in tcg2_measure_pe_image().
> The first one in efi_search_protocol() and the second on in the device path
> calculation.  The second isn't even a function we should be calling, but a
> pointer assignment, which happens to work with the existing macro.

It is a quite common mistake.
For most people, it is not very trivial when we should use EFI_CALL
and when should not.
Do you think that we should leave a note somewhere?

It would be much better if we can check any occurrence of mismatch,
say using EFI_CALL for a non-EFIAPI function, at compile time.

-Takahiro Akashi

> While at it switch the malloc call to a calloc, remove the unnecessary cast
> and get rid of an unneeded if statement before copying the device path
> 
> Signed-off-by: Ilias Apalodimas <ilias.apalodimas@linaro.org>
> ---
>  lib/efi_loader/efi_tcg2.c | 15 ++++++---------
>  1 file changed, 6 insertions(+), 9 deletions(-)
> 
> diff --git a/lib/efi_loader/efi_tcg2.c b/lib/efi_loader/efi_tcg2.c
> index 1319a8b37868..d026af2b2350 100644
> --- a/lib/efi_loader/efi_tcg2.c
> +++ b/lib/efi_loader/efi_tcg2.c
> @@ -839,20 +839,19 @@ efi_status_t tcg2_measure_pe_image(void *efi, u64 efi_size,
>  	if (ret != EFI_SUCCESS)
>  		return ret;
>  
> -	ret = EFI_CALL(efi_search_protocol(&handle->header,
> -					   &efi_guid_loaded_image_device_path,
> -					   &handler));
> +	ret = efi_search_protocol(&handle->header,
> +				  &efi_guid_loaded_image_device_path, &handler);
>  	if (ret != EFI_SUCCESS)
>  		return ret;
>  
> -	device_path = EFI_CALL(handler->protocol_interface);
> +	device_path = handler->protocol_interface;
>  	device_path_length = efi_dp_size(device_path);
>  	if (device_path_length > 0) {
>  		/* add end node size */
>  		device_path_length += sizeof(struct efi_device_path);
>  	}
>  	event_size = sizeof(struct uefi_image_load_event) + device_path_length;
> -	image_load_event = (struct uefi_image_load_event *)malloc(event_size);
> +	image_load_event = calloc(1, event_size);
>  	if (!image_load_event)
>  		return EFI_OUT_OF_RESOURCES;
>  
> @@ -875,10 +874,8 @@ efi_status_t tcg2_measure_pe_image(void *efi, u64 efi_size,
>  		goto out;
>  	}
>  
> -	if (device_path_length > 0) {
> -		memcpy(image_load_event->device_path, device_path,
> -		       device_path_length);
> -	}
> +	/* device_path_length might be zero */
> +	memcpy(image_load_event->device_path, device_path, device_path_length);
>  
>  	ret = tcg2_agile_log_append(pcr_index, event_type, &digest_list,
>  				    event_size, (u8 *)image_load_event);
> -- 
> 2.33.0
>