[PATCH v1 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     |  2 ++
 MdeModulePkg/Core/Dxe/Event/Timer.c | 14 ++++++++++----
 2 files changed, 12 insertions(+), 4 deletions(-)

diff --git a/MdeModulePkg/Core/Dxe/DxeMain.h b/MdeModulePkg/Core/Dxe/DxeMain.h
index 815a6b4bd844..acf0b244aeda 100644
--- a/MdeModulePkg/Core/Dxe/DxeMain.h
+++ b/MdeModulePkg/Core/Dxe/DxeMain.h
@@ -1538,6 +1538,8 @@ 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..1621814ef3c5 100644
--- a/MdeModulePkg/Core/Dxe/Event/Timer.c
+++ b/MdeModulePkg/Core/Dxe/Event/Timer.c
@@ -229,6 +229,8 @@ 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 +257,14 @@ CoreSetTimer (
     return EFI_INVALID_PARAMETER;
   }
 
+  if ((Type != TimerCancel) && (TriggerTime == 0)) {
+    if (gTimer) {
+      gTimer->GetTimerPeriod (gTimer, &TriggerTime);
+    } else {
+      return EFI_NOT_READY;
+    }
+  }
+
   CoreAcquireLock (&mEfiTimerLock);
 
   //
@@ -270,10 +280,6 @@ CoreSetTimer (
 
   if (Type != TimerCancel) {
     if (Type == TimerPeriodic) {
-      if (TriggerTime == 0) {
-        gTimer->GetTimerPeriod (gTimer, &TriggerTime);
-      }
-
       Event->Timer.Period = TriggerTime;
     }
 
-- 
2.25.1