[PATCH v2 1/1] MdeModulePkg/Core: Fix the potential hang of calling SetTimer.

["Ying-Tsun Huang" <ying-tsun.huang@amd.com>]

When calling SetTimer with Type is not TimerCancel and TriggerTime is 0,
gTimer is used to get the timer period. However, gTimer is NULL before
EFI_TIMER_ARCH_PROTOCOL is installed. Adding the check of gTimer and
return EFI_NOT_READY to avoid the hang.

Cc: Jian J Wang <jian.j.wang@intel.com>
Cc: Dandan Bi <dandan.bi@intel.com>
Cc: Liming Gao <gaoliming@byosoft.com.cn>
Signed-off-by: Ying-Tsun Huang <ying-tsun.huang@amd.com>
---
 MdeModulePkg/Core/Dxe/DxeMain.h     |  3 +++
 MdeModulePkg/Core/Dxe/Event/Timer.c | 17 +++++++++++++----
 2 files changed, 16 insertions(+), 4 deletions(-)

diff --git a/MdeModulePkg/Core/Dxe/DxeMain.h b/MdeModulePkg/Core/Dxe/DxeMain.h
index 815a6b4bd844..182d9c3537ad 100644
--- a/MdeModulePkg/Core/Dxe/DxeMain.h
+++ b/MdeModulePkg/Core/Dxe/DxeMain.h
@@ -3,6 +3,7 @@
   internal structure and functions used by DxeCore module.
 
 Copyright (c) 2006 - 2018, Intel Corporation. All rights reserved.<BR>
+Copyright (c) 2022, AMD Incorporated. All rights reserved.<BR>
 SPDX-License-Identifier: BSD-2-Clause-Patent
 
 **/
@@ -1538,6 +1539,8 @@ CoreCreateEventInternal (
   @retval EFI_SUCCESS            The event has been set to be signaled at the
                                  requested time
   @retval EFI_INVALID_PARAMETER  Event or Type is not valid
+  @retval EFI_NOT_READY          Type is not TimerCancel, TriggerTime is 0, but
+                                 EFI_TIMER_ARCH_PROTOCOL is not installed yet
 
 **/
 EFI_STATUS
diff --git a/MdeModulePkg/Core/Dxe/Event/Timer.c b/MdeModulePkg/Core/Dxe/Event/Timer.c
index 29e507c67c50..f630cf5dad61 100644
--- a/MdeModulePkg/Core/Dxe/Event/Timer.c
+++ b/MdeModulePkg/Core/Dxe/Event/Timer.c
@@ -2,6 +2,7 @@
   Core Timer Services
 
 Copyright (c) 2006 - 2013, Intel Corporation. All rights reserved.<BR>
+Copyright (c) 2022, AMD Incorporated. All rights reserved.<BR>
 SPDX-License-Identifier: BSD-2-Clause-Patent
 
 **/
@@ -229,6 +230,8 @@ CoreTimerTick (
   @retval EFI_SUCCESS            The event has been set to be signaled at the
                                  requested time
   @retval EFI_INVALID_PARAMETER  Event or Type is not valid
+  @retval EFI_NOT_READY          Type is not TimerCancel, TriggerTime is 0, but
+                                 EFI_TIMER_ARCH_PROTOCOL is not installed yet
 
 **/
 EFI_STATUS
@@ -255,6 +258,16 @@ CoreSetTimer (
     return EFI_INVALID_PARAMETER;
   }
 
+  if ((Type != TimerCancel) && (TriggerTime == 0)) {
+    if (gTimer) {
+      gTimer->GetTimerPeriod (gTimer, &TriggerTime);
+    } else {
+      DEBUG ((DEBUG_ERROR, "EFI_TIMER_ARCH_PROTOCOL is not installed. Unable to get timer period.\n"));
+      ASSERT (FALSE);
+      return EFI_NOT_READY;
+    }
+  }
+
   CoreAcquireLock (&mEfiTimerLock);
 
   //
@@ -270,10 +283,6 @@ CoreSetTimer (
 
   if (Type != TimerCancel) {
     if (Type == TimerPeriodic) {
-      if (TriggerTime == 0) {
-        gTimer->GetTimerPeriod (gTimer, &TriggerTime);
-      }
-
       Event->Timer.Period = TriggerTime;
     }
 
-- 
2.25.1