[edk2-platforms][PATCH v4 11/12] Ext4Pkg: Filter out directory entry names containing \0 as invalid

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

The directory entry name conventions forbid having null-terminator
symbols in its body and can lead to undefined behavior conditions
and crashes

Cc: Marvin Häuser <mhaeuser@posteo.de>
Cc: Pedro Falcato <pedro.falcato@gmail.com>
Cc: Vitaly Cheptsov <vit9696@protonmail.com>
Fixes: 89b2bb0db263 ("Ext4Pkg: Fix and clarify handling regarding non-utf8 dir entries")
Signed-off-by: Savva Mitrofanov <savvamtr@gmail.com>
Reviewed-by: Pedro Falcato <pedro.falcato@gmail.com>
---
 Features/Ext4Pkg/Ext4Dxe/Directory.c | 9 ++++++++-
 1 file changed, 8 insertions(+), 1 deletion(-)

diff --git a/Features/Ext4Pkg/Ext4Dxe/Directory.c b/Features/Ext4Pkg/Ext4Dxe/Directory.c
index dee8cfc66cb7..88f89a40534c 100644
--- a/Features/Ext4Pkg/Ext4Dxe/Directory.c
+++ b/Features/Ext4Pkg/Ext4Dxe/Directory.c
@@ -28,9 +28,16 @@ Ext4GetUcs2DirentName (
 {
   CHAR8       Utf8NameBuf[EXT4_NAME_MAX + 1];
   UINT16      *Str;
+  UINT8       Index;
   EFI_STATUS  Status;
 
-  CopyMem (Utf8NameBuf, Entry->name, Entry->name_len);
+  for (Index = 0; Index < Entry->name_len; ++Index) {
+    if (Entry->name[Index] == '\0') {
+      return EFI_INVALID_PARAMETER;
+    }
+
+    Utf8NameBuf[Index] = Entry->name[Index];
+  }
 
   Utf8NameBuf[Entry->name_len] = '\0';
 
-- 
2.39.1