From 1009b59b6525c16724fe2684c344a6359af28b55 Mon Sep 17 00:00:00 2001
From: Marvin Haeuser <mhaeuser@outlook.de>
Date: Sun, 20 Oct 2019 20:08:31 +0800
Subject: [PATCH] MdePkg/UefiFileHandleLib: Fix potential NULL dereference

REF: https://bugzilla.tianocore.org/show_bug.cgi?id=2293

Move the NULL check in FileHandleGetInfo() to directly after the
allocation to prevent potential NULL dereferences.

Cc: Michael D Kinney <michael.d.kinney@intel.com>
Cc: Liming Gao <liming.gao@intel.com>
Signed-off-by: Marvin Haeuser <mhaeuser@outlook.de>
Reviewed-by: Liming Gao <liming.gao@intel.com>
---
 .../UefiFileHandleLib/UefiFileHandleLib.c     | 28 ++++++++++---------
 1 file changed, 15 insertions(+), 13 deletions(-)

diff --git a/MdePkg/Library/UefiFileHandleLib/UefiFileHandleLib.c b/MdePkg/Library/UefiFileHandleLib/UefiFileHandleLib.c
index 96913c5c02..5dc893833a 100644
--- a/MdePkg/Library/UefiFileHandleLib/UefiFileHandleLib.c
+++ b/MdePkg/Library/UefiFileHandleLib/UefiFileHandleLib.c
@@ -68,19 +68,21 @@ FileHandleGetInfo (
     // error is expected.  getting size to allocate
     //
     FileInfo = AllocateZeroPool(FileInfoSize);
-    //
-    // now get the information
-    //
-    Status = FileHandle->GetInfo(FileHandle,
-                                 &gEfiFileInfoGuid,
-                                 &FileInfoSize,
-                                 FileInfo);
-    //
-    // if we got an error free the memory and return NULL
-    //
-    if (EFI_ERROR(Status) && (FileInfo != NULL)) {
-      FreePool(FileInfo);
-      FileInfo = NULL;
+    if (FileInfo != NULL) {
+      //
+      // now get the information
+      //
+      Status = FileHandle->GetInfo(FileHandle,
+                                   &gEfiFileInfoGuid,
+                                   &FileInfoSize,
+                                   FileInfo);
+      //
+      // if we got an error free the memory and return NULL
+      //
+      if (EFI_ERROR(Status)) {
+        FreePool(FileInfo);
+        FileInfo = NULL;
+      }
     }
   }
   return (FileInfo);
-- 
2.39.5