From 571ddac16048dfba4b25b04fe5cbd706c392b5ba Mon Sep 17 00:00:00 2001
From: Vishnu Banavath <vishnu.banavath@arm.com>
Date: Fri, 24 Dec 2021 19:17:17 +0000
Subject: [PATCH] smm_gateway: add checks for null attributes

As par EDK-2 and EDK-2 test code, when a user issue's
setVariable() with 0 in attributes field, it means a variable
delete request. Currently, smm gatway doesn't handle this scenario.
This change is to add that support

Signed-off-by: Vishnu Banavath <vishnu.banavath@arm.com>

Upstream-Status: Pending [Not submitted to upstream yet]
Signed-off-by: Vishnu Banavath <vishnu.banavath@arm.com>


---
 .../backend/uefi_variable_store.c             | 28 ++++++++++++-------
 1 file changed, 18 insertions(+), 10 deletions(-)

diff --git a/components/service/smm_variable/backend/uefi_variable_store.c b/components/service/smm_variable/backend/uefi_variable_store.c
index a57b3346..e8771c21 100644
--- a/components/service/smm_variable/backend/uefi_variable_store.c
+++ b/components/service/smm_variable/backend/uefi_variable_store.c
@@ -167,7 +167,9 @@ efi_status_t uefi_variable_store_set_variable(
 	* EFI_VARIABLE_RUNTIME_ACCESS set must also have EFI_VARIABLE_BOOTSERVICE_ACCESS set.
 	* The caller is responsible for following this rule.
 	*/
-	if((var->Attributes & EFI_VARIABLE_RUNTIME_ACCESS))
+	if (!var->Attributes)
+		EMSG("It might be a delete variable request\n");
+	else if((var->Attributes & EFI_VARIABLE_RUNTIME_ACCESS))
 	{
 			if((var->Attributes & EFI_VARIABLE_BOOTSERVICE_ACCESS) != EFI_VARIABLE_BOOTSERVICE_ACCESS )
 			return EFI_INVALID_PARAMETER;
@@ -191,7 +193,7 @@ efi_status_t uefi_variable_store_set_variable(
 				(var->Attributes & EFI_VARIABLE_NON_VOLATILE) ||
 				(info->is_variable_set && (info->metadata.attributes & EFI_VARIABLE_NON_VOLATILE));
 
-			if (var->DataSize) {
+			if (var->DataSize && var->Attributes) {
 
 				/* It's a set rather than a remove operation */
 				variable_index_update_variable(
@@ -206,7 +208,9 @@ efi_status_t uefi_variable_store_set_variable(
 				 * that it's never possible for an object to exist within
 				 * the storage backend without a corresponding index entry.
 				 */
-				remove_variable_data(context, info);
+				EMSG("  deleting variable %s \n",var->Name);
+				if (remove_variable_data(context, info) != PSA_SUCCESS)
+					EMSG("  deleting variable %s FAILED\n",var->Name);
 				variable_index_remove_variable(&context->variable_index, info);
 
 				/* Variable info no longer valid */
@@ -587,14 +591,18 @@ static efi_status_t check_access_permitted_on_set(
 	}
 
 	if ((status == EFI_SUCCESS) && var->DataSize) {
-
+		/* Delete the variable with Attributes is 0 */
+		if (!var->Attributes) {
+			EMSG("Null attributes, may be a delete variable request\n");
+			status = EFI_SUCCESS;
+		}
 		/* Restrict which attributes can be modified for an existing variable */
-        if (((var->Attributes & EFI_VARIABLE_NON_VOLATILE) !=
-            (info->metadata.attributes & EFI_VARIABLE_NON_VOLATILE)) ||
-            ((var->Attributes & EFI_VARIABLE_BOOTSERVICE_ACCESS) !=
-            (info->metadata.attributes & EFI_VARIABLE_BOOTSERVICE_ACCESS)) ||
-            ((var->Attributes & EFI_VARIABLE_RUNTIME_ACCESS) !=
-            (info->metadata.attributes & EFI_VARIABLE_RUNTIME_ACCESS))) {
+		else if (((var->Attributes & EFI_VARIABLE_NON_VOLATILE) !=
+			(info->metadata.attributes & EFI_VARIABLE_NON_VOLATILE)) ||
+			((var->Attributes & EFI_VARIABLE_BOOTSERVICE_ACCESS) !=
+			(info->metadata.attributes & EFI_VARIABLE_BOOTSERVICE_ACCESS)) ||
+			((var->Attributes & EFI_VARIABLE_RUNTIME_ACCESS) !=
+			(info->metadata.attributes & EFI_VARIABLE_RUNTIME_ACCESS))) {
 			/* Don't permit change of attributes */
 			status = EFI_INVALID_PARAMETER;
 		}