[edk2-platforms][PATCH v4 04/12] Ext4Pkg: Add inode number validity check

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

We need to validate inode number to prevent reading non-existent and
incorrect inodes so we checks that inode number valid across opened
partition before we read it in Ext4ReadInode.

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>
---
 Features/Ext4Pkg/Ext4Dxe/Ext4Disk.h   | 13 +++++++++++--
 Features/Ext4Pkg/Ext4Dxe/Ext4Dxe.h    | 12 ++++++++++++
 Features/Ext4Pkg/Ext4Dxe/BlockGroup.c |  5 +++++
 3 files changed, 28 insertions(+), 2 deletions(-)

diff --git a/Features/Ext4Pkg/Ext4Dxe/Ext4Disk.h b/Features/Ext4Pkg/Ext4Dxe/Ext4Disk.h
index d0a455d0e572..70cb6c3209dd 100644
--- a/Features/Ext4Pkg/Ext4Dxe/Ext4Disk.h
+++ b/Features/Ext4Pkg/Ext4Dxe/Ext4Disk.h
@@ -484,8 +484,17 @@ typedef UINT64  EXT4_BLOCK_NR;
 typedef UINT32  EXT2_BLOCK_NR;
 typedef UINT32  EXT4_INO_NR;
 
-// 2 is always the root inode number in ext4
-#define EXT4_ROOT_INODE_NR  2
+/* Special inode numbers */
+#define EXT4_ROOT_INODE_NR         2
+#define EXT4_USR_QUOTA_INODE_NR    3
+#define EXT4_GRP_QUOTA_INODE_NR    4
+#define EXT4_BOOT_LOADER_INODE_NR  5
+#define EXT4_UNDEL_DIR_INODE_NR    6
+#define EXT4_RESIZE_INODE_NR       7
+#define EXT4_JOURNAL_INODE_NR      8
+
+/* First non-reserved inode for old ext4 filesystems */
+#define EXT4_GOOD_OLD_FIRST_INODE_NR  11
 
 #define EXT4_BLOCK_FILE_HOLE  0
 
diff --git a/Features/Ext4Pkg/Ext4Dxe/Ext4Dxe.h b/Features/Ext4Pkg/Ext4Dxe/Ext4Dxe.h
index f608def7c9eb..c977a97ca5c2 100644
--- a/Features/Ext4Pkg/Ext4Dxe/Ext4Dxe.h
+++ b/Features/Ext4Pkg/Ext4Dxe/Ext4Dxe.h
@@ -287,6 +287,18 @@ Ext4GetBlockGroupDesc (
   IN UINT32          BlockGroup
   );
 
+/**
+   Checks inode number validity across superblock of the opened partition.
+   Currently we don't have logic to process defective blocks with
+   inode number equal 1, so we don't reject them at this point
+
+   @param[in]  Partition      Pointer to the opened ext4 partition.
+
+   @return TRUE if inode number is valid.
+**/
+#define EXT4_IS_VALID_INODE_NR(Partition, InodeNum)                            \
+  (((InodeNum) > 0) && (InodeNum) <= (Partition->SuperBlock.s_inodes_count))
+
 /**
    Reads an inode from disk.
 
diff --git a/Features/Ext4Pkg/Ext4Dxe/BlockGroup.c b/Features/Ext4Pkg/Ext4Dxe/BlockGroup.c
index cba96cd95afc..f34cdc5dbad7 100644
--- a/Features/Ext4Pkg/Ext4Dxe/BlockGroup.c
+++ b/Features/Ext4Pkg/Ext4Dxe/BlockGroup.c
@@ -50,6 +50,11 @@ Ext4ReadInode (
   EXT4_BLOCK_NR          InodeTableStart;
   EFI_STATUS             Status;
 
+  if (!EXT4_IS_VALID_INODE_NR (Partition, InodeNum)) {
+    DEBUG ((DEBUG_ERROR, "[ext4] Error reading inode: inode number %lu isn't valid\n", InodeNum));
+    return EFI_VOLUME_CORRUPTED;
+  }
+
   BlockGroupNumber = (UINT32)DivU64x64Remainder (
                                InodeNum - 1,
                                Partition->SuperBlock.s_inodes_per_group,
-- 
2.39.1