MdeModulePkg/DxeCore: Please static checker for false report

After commit 57df17fe26, some static check reports suspicious NULL pointer
deference at line:

  Entry->MachineType = Entry->Emulator->MachineType;
                       ^^^^^^^^^^^^^^^

within function PeCoffEmuProtocolNotify().

However, 'Entry->Emulator' is guaranteed to have a non-NULL value when
previous call to the CoreHandleProtocol() returns EFI_SUCCESS.

This commit will re-write the return status check for CoreHandleProtocol()
to add explicit NULL pointer check for protocol instance pointer.

Cc: Jian J Wang <jian.j.wang@intel.com>
Signed-off-by: Hao Wu <hao.a.wu@intel.com>
Acked-by: Ard Biesheuvel <ard.biesheuvel@linaro.org>
Reviewed-by: Liming Gao <liming.gao@intel.com>
Reviewed-by: Michael D Kinney <michael.d.kinney@intel.com>

1 files changed, 14 insertions, 9 deletions

diff --git a/MdeModulePkg/Core/Dxe/Image/Image.c b/MdeModulePkg/Core/Dxe/Image/Image.c
index 08306a73fd..de5b8bed27 100644
--- a/MdeModulePkg/Core/Dxe/Image/Image.c
+++ b/MdeModulePkg/Core/Dxe/Image/Image.c
@@ -134,12 +134,14 @@ PeCoffEmuProtocolNotify (
   IN  VOID            *Context

   )

 {

-  EFI_STATUS          Status;

-  UINTN               BufferSize;

-  EFI_HANDLE          EmuHandle;

-  EMULATOR_ENTRY      *Entry;

+  EFI_STATUS                            Status;

+  UINTN                                 BufferSize;

+  EFI_HANDLE                            EmuHandle;

+  EDKII_PECOFF_IMAGE_EMULATOR_PROTOCOL  *Emulator;

+  EMULATOR_ENTRY                        *Entry;

 

   EmuHandle = NULL;

+  Emulator  = NULL;

 

   while (TRUE) {

     BufferSize = sizeof (EmuHandle);

@@ -157,16 +159,19 @@ PeCoffEmuProtocolNotify (
       return;

     }

 

-    Entry = AllocateZeroPool (sizeof (*Entry));

-    ASSERT (Entry != NULL);

-

     Status = CoreHandleProtocol (

                EmuHandle,

                &gEdkiiPeCoffImageEmulatorProtocolGuid,

-               (VOID **)&Entry->Emulator

+               (VOID **)&Emulator

                );

-    ASSERT_EFI_ERROR (Status);

+    if (EFI_ERROR (Status) || Emulator == NULL) {

+      continue;

+    }

+

+    Entry = AllocateZeroPool (sizeof (*Entry));

+    ASSERT (Entry != NULL);

 

+    Entry->Emulator    = Emulator;

     Entry->MachineType = Entry->Emulator->MachineType;

 

     InsertTailList (&mAvailableEmulators, &Entry->Link);