lib: find_in_variable_esl(): Fix a tiny nitpick clang-analyze has.

clang-analyze believes the following:

311	EFI_STATUS
312	variable_enroll_hash(CHAR16 *var, EFI_GUID owner,
313			     UINT8 hash[SHA256_DIGEST_SIZE])
314	{
315		EFI_STATUS efi_status;
316
317		efi_status = find_in_variable_esl(var, owner, hash, SHA256_DIGEST_SIZE);
>               Calling 'find_in_variable_esl' →

260	EFI_STATUS
261	find_in_variable_esl(CHAR16* var, EFI_GUID owner, UINT8 *key, UINTN keylen)
262	{
263		UINTN DataSize;
264		UINT8 *Data;
>               ← 'Data' declared without an initial value →
265		EFI_STATUS efi_status;
266
267		efi_status = get_variable(var, &Data, &DataSize, owner);
>               ← Calling 'get_variable' →

237	EFI_STATUS
238	get_variable(CHAR16 *var, UINT8 **data, UINTN *len, EFI_GUID owner)
239	{
240		return get_variable_attr(var, data, len, owner, NULL);
>		← Calling 'get_variable_attr' →

213	EFI_STATUS
214	get_variable_attr(CHAR16 *var, UINT8 **data, UINTN *len, EFI_GUID owner,
215			  UINT32 *attributes)
216	{
217		EFI_STATUS efi_status;
218
219		*len = 0;
220
221		efi_status = GetVariable(var, &owner, NULL, len, NULL);
>		← Calling 'GetVariable' →
>		← Returning from 'GetVariable' →
222		if (efi_status != EFI_BUFFER_TOO_SMALL)
>		← Assuming the condition is true →
>		← Taking true branch →
223			return efi_status;
224
225		*data = AllocateZeroPool(*len);
226		if (!*data)
227			return EFI_OUT_OF_RESOURCES;
228
229		efi_status = GetVariable(var, &owner, attributes, len, *data);
230		if (EFI_ERROR(efi_status)) {
231			FreePool(*data);
232			*data = NULL;
233		}
234		return efi_status;
235	}

And it can't figure out that the first GetVariable() call will, in fact,
always return EFI_BUFFER_TOO_SMALL, and that AllocateZeroPool() will
then *correctly* clobber the two variables we never assigned the value
from.  It also then believes that efi_status might have been returned
/without/ being an error, and thinks that means we'll use the
uninitialized pointer.

This won't happen, but hey, let's make the code better express to the
checker what is intended.

Signed-off-by: Peter Jones <pjones@redhat.com>

1 files changed, 7 insertions, 4 deletions

diff --git a/lib/variables.c b/lib/variables.c
index 044ddae5..7c28eaa5 100644
--- a/lib/variables.c
+++ b/lib/variables.c
@@ -211,13 +211,16 @@ get_variable_attr(CHAR16 *var, UINT8 **data, UINTN *len, EFI_GUID owner,
 
 	efi_status = uefi_call_wrapper(RT->GetVariable, 5, var, &owner,
 				       NULL, len, NULL);
-	if (efi_status != EFI_BUFFER_TOO_SMALL)
+	if (efi_status != EFI_BUFFER_TOO_SMALL) {
+		if (!EFI_ERROR(efi_status)) /* this should never happen */
+			return EFI_PROTOCOL_ERROR;
 		return efi_status;
+	}
 
 	*data = AllocateZeroPool(*len);
 	if (!*data)
 		return EFI_OUT_OF_RESOURCES;
-	
+
 	efi_status = uefi_call_wrapper(RT->GetVariable, 5, var, &owner,
 				       attributes, len, *data);
 
@@ -254,8 +257,8 @@ find_in_esl(UINT8 *Data, UINTN DataSize, UINT8 *key, UINTN keylen)
 EFI_STATUS
 find_in_variable_esl(CHAR16* var, EFI_GUID owner, UINT8 *key, UINTN keylen)
 {
-	UINTN DataSize;
-	UINT8 *Data;
+	UINTN DataSize = 0;
+	UINT8 *Data = NULL;
 	EFI_STATUS status;
 
 	status = get_variable(var, &Data, &DataSize, owner);