[PATCH] efi_loader: Change the return values if a TPM is missing during GetEventLog

[Ilias Apalodimas]

The function defined by the TCG spec looks like:

typedef
EFI_STATUS
(EFIAPI *EFI_TCG2_GET_EVENT_LOG) (
 IN EFI_TCG2_PROTOCOL *This,
 IN EFI_TCG2_EVENT_LOG_FORMAT EventLogFormat,
 OUT EFI_PHYSICAL_ADDRESS *EventLogLocation,
 OUT EFI_PHYSICAL_ADDRESS *EventLogLastEntry,
 OUT BOOLEAN *EventLogTruncated
);
and the spec mandates that
"If no TPM is present, the function SHALL set the following values and return
        EFI_SUCCESS:
        EventLogLocation = NULL
        EventLogLastEntry = NULL
        EventLogTruncated = FALSE"

However, if we set it to NULL the local assignment is discarded when the
function returns. Set it to 0, although on some platforms that's a valid
address.

Signed-off-by: Ilias Apalodimas <ilias.apalodi...@linaro.org>
---
 lib/efi_loader/efi_tcg2.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/lib/efi_loader/efi_tcg2.c b/lib/efi_loader/efi_tcg2.c
index 1d52a04ca48f..07637df7660b 100644
--- a/lib/efi_loader/efi_tcg2.c
+++ b/lib/efi_loader/efi_tcg2.c
@@ -352,8 +352,8 @@ efi_tcg2_get_eventlog(struct efi_tcg2_protocol *this,
        }
 
        if (tcg2_platform_get_tpm2(&dev)) {
-               event_log_location = NULL;
-               event_log_last_entry = NULL;
+               *event_log_location = 0;
+               *event_log_last_entry = 0;
                *event_log_truncated = false;
                ret = EFI_SUCCESS;
                goto out;
-- 
2.53.0