[U-Boot] [RFC] efi_loader: workaround for EDK2's shell.efi

Alexander Graf agraf at suse.de
Thu Aug 9 06:55:06 UTC 2018



On 09.08.18 07:15, AKASHI Takahiro wrote:
> The commit 21b3edfc964 ("efi_loader: check parameters of CreateEvent")
> enforces a strict parameter check at CreateEvent().  Unfortunately,
> however, EDK2's Shell.efi calls this function with notify_tpl == 0.
> 
> The patch above does right thing and we'd better fix the issue on EDK2
> side, and yet we might want a workaround allowing for running un-modified
> version of EDK2 in short-term solution.

... of the EDK2 shell ...

and it's not just about short term - we always want to be compatible :).

So what's the reason this does not trigger in edk2? Are they considering
TPL 0 a valid TPL always or did they just forget the check in create
event? If they always consider TPL 0 valid, we better change
is_valid_tpl to ensure compatibility with edk2's behavior.

> The patch provides a minimum mitigation of parameter check.
> 
> Signed-off-by: AKASHI Takahiro <takahiro.akashi at linaro.org>
> ---
>  lib/efi_loader/efi_boottime.c | 3 ++-
>  1 file changed, 2 insertions(+), 1 deletion(-)
> 
> diff --git a/lib/efi_loader/efi_boottime.c b/lib/efi_loader/efi_boottime.c
> index 2281703f261..e7a19c35415 100644
> --- a/lib/efi_loader/efi_boottime.c
> +++ b/lib/efi_loader/efi_boottime.c
> @@ -627,7 +627,8 @@ efi_status_t efi_create_event(uint32_t type, efi_uintn_t notify_tpl,
>  		return EFI_INVALID_PARAMETER;
>  	}
>  
> -	if (is_valid_tpl(notify_tpl) != EFI_SUCCESS)
> +	/* notify_tpl == 0: workaround for EDK2's Shell.efi */

That comment is too undescriptive. Better write something like "EDK2
accepts TPL 0 in CreateEvent, so to ensure compatibility we should do
the same. EDK2 Shell.efi depends on this."


Alex

> +	if (notify_tpl && (is_valid_tpl(notify_tpl) != EFI_SUCCESS))
>  		return EFI_INVALID_PARAMETER;
>  
>  	evt = calloc(1, sizeof(struct efi_event));
> 


More information about the U-Boot mailing list