[edk2-platforms][PATCH v4 07/12] Ext4Pkg: Check that source file is directory in Ext4OpenInternal

["Savva Mitrofanov" <savvamtr@gmail.com>]

This check already present in the while loop below, but absent for cases
when input file is nameless, so to handle assertion in Ext4ReadFile we
need to add it at the top of function

Cc: Marvin Häuser <mhaeuser@posteo.de>
Cc: Pedro Falcato <pedro.falcato@gmail.com>
Cc: Vitaly Cheptsov <vit9696@protonmail.com>
Fixes: d9ceedca6c8f ("Ext4Pkg: Add Ext4Dxe driver.")
Signed-off-by: Savva Mitrofanov <savvamtr@gmail.com>
Reviewed-by: Pedro Falcato <pedro.falcato@gmail.com>
Reviewed-by: Marvin Häuser <mhaeuser@posteo.de>
---
 Features/Ext4Pkg/Ext4Dxe/File.c | 13 +++++++++----
 1 file changed, 9 insertions(+), 4 deletions(-)

diff --git a/Features/Ext4Pkg/Ext4Dxe/File.c b/Features/Ext4Pkg/Ext4Dxe/File.c
index 8dfe324255f4..9dde4a5d1a2d 100644
--- a/Features/Ext4Pkg/Ext4Dxe/File.c
+++ b/Features/Ext4Pkg/Ext4Dxe/File.c
@@ -207,6 +207,11 @@ Ext4OpenInternal (
   Level     = 0;
 
   DEBUG ((DEBUG_FS, "[ext4] Ext4OpenInternal %s\n", FileName));
+
+  if (!Ext4FileIsDir (Current)) {
+    return EFI_INVALID_PARAMETER;
+  }
+
   // If the path starts with a backslash, we treat the root directory as the base directory
   if (FileName[0] == L'\\') {
     FileName++;
@@ -219,6 +224,10 @@ Ext4OpenInternal (
       return EFI_ACCESS_DENIED;
     }
 
+    if (!Ext4FileIsDir (Current)) {
+      return EFI_INVALID_PARAMETER;
+    }
+
     // Discard leading path separators
     while (FileName[0] == L'\\') {
       FileName++;
@@ -242,10 +251,6 @@ Ext4OpenInternal (
 
     DEBUG ((DEBUG_FS, "[ext4] Opening %s\n", PathSegment));
 
-    if (!Ext4FileIsDir (Current)) {
-      return EFI_INVALID_PARAMETER;
-    }
-
     if (!Ext4IsLastPathSegment (FileName)) {
       if (!Ext4DirCanLookup (Current)) {
         return EFI_ACCESS_DENIED;
-- 
2.39.1