From 9478bbcd1d8a03762924a0b4533c1b84cbfcaa57 Mon Sep 17 00:00:00 2001
From: Heinrich Schuchardt <xypron.glpk@gmx.de>
Date: Fri, 5 Apr 2019 03:06:18 +0200
Subject: [PATCH 1/1] ShellPkg/CommandLib: avoid NULL derefence and memory leak

Since TianoCore EDK2 commit d65f2cea36d1 ("ShellPkg/CommandLib: Locate
proper UnicodeCollation instance") in edk2 the UEFI Shell crashes if EFI
variable PlatformLang is not defined due to dereferencing gUnicodeCollation
gUnicodeCollation (= NULL) in ShellCommandRegisterCommandName().

Furthermore CommandInit() is leaking PlatformLang if
gUnicodeCollation != NULL.

Close the memory leak and use the first UnicodeCollation instance if
PlatfomLang is not defined.

Fixes: d65f2cea36d1 ("ShellPkg/CommandLib: Locate proper UnicodeCollation
instance")
Contributed-under: TianoCore Contribution Agreement 1.1
Signed-off-by: Heinrich Schuchardt <xypron.glpk@gmx.de>
---
 .../UefiShellCommandLib/UefiShellCommandLib.c | 20 +++++++++++++------
 1 file changed, 14 insertions(+), 6 deletions(-)

diff --git a/ShellPkg/Library/UefiShellCommandLib/UefiShellCommandLib.c b/ShellPkg/Library/UefiShellCommandLib/UefiShellCommandLib.c
index ddc4bb1567..e60279e5ac 100644
--- a/ShellPkg/Library/UefiShellCommandLib/UefiShellCommandLib.c
+++ b/ShellPkg/Library/UefiShellCommandLib/UefiShellCommandLib.c
@@ -80,12 +80,10 @@ CommandInit(
   EFI_STATUS                      Status;
   CHAR8                           *PlatformLang;
 
-  GetEfiGlobalVariable2 (EFI_PLATFORM_LANG_VARIABLE_NAME, (VOID**)&PlatformLang, NULL);
-  if (PlatformLang == NULL) {
-    return EFI_UNSUPPORTED;
-  }
-
   if (gUnicodeCollation == NULL) {
+
+    GetEfiGlobalVariable2 (EFI_PLATFORM_LANG_VARIABLE_NAME, (VOID**)&PlatformLang, NULL);
+
     Status = gBS->LocateHandleBuffer (
                     ByProtocol,
                     &gEfiUnicodeCollation2ProtocolGuid,
@@ -113,6 +111,14 @@ CommandInit(
         continue;
       }
 
+      //
+      // Without clue provided use the first Unicode Collation2 protocol.
+      //
+      if (PlatformLang == NULL) {
+        gUnicodeCollation = Uc;
+        break;
+      }
+
       //
       // Find the best matching matching language from the supported languages
       // of Unicode Collation2 protocol.
@@ -132,7 +138,9 @@ CommandInit(
     if (Handles != NULL) {
       FreePool (Handles);
     }
-    FreePool (PlatformLang);
+    if (PlatformLang != NULL) {
+      FreePool (PlatformLang);
+    }
   }
 
   return (gUnicodeCollation == NULL) ? EFI_UNSUPPORTED : EFI_SUCCESS;
-- 
2.20.1