We need to validate inode number to prevent possible null-pointer
dereference of directory parent in Ext4OpenDirent. Also checks that
inode number valid across opened partition before we read it in
Ext4ReadInode.
Cc: Marvin Häuser <mhaeu...@posteo.de>
Cc: Pedro Falcato <pedro.falc...@gmail.com>
Cc: Vitaly Cheptsov <vit9...@protonmail.com>
Fixes: d9ceedca6c8f ("Ext4Pkg: Add Ext4Dxe driver.")
Signed-off-by: Savva Mitrofanov <savva...@gmail.com>
---
Features/Ext4Pkg/Ext4Dxe/Ext4Disk.h | 13 ++++++++--
Features/Ext4Pkg/Ext4Dxe/Ext4Dxe.h | 25 ++++++++++++++++++++
Features/Ext4Pkg/Ext4Dxe/BlockGroup.c | 5 ++++
Features/Ext4Pkg/Ext4Dxe/Directory.c | 10 ++++++++
4 files changed, 51 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..2e489ce4dd86 100644
--- a/Features/Ext4Pkg/Ext4Dxe/Ext4Dxe.h
+++ b/Features/Ext4Pkg/Ext4Dxe/Ext4Dxe.h
@@ -287,6 +287,31 @@ Ext4GetBlockGroupDesc (
IN UINT32 BlockGroup
);
+/**
+ Retrieves the first usable non-reserved inode number from the superblock
+ of the opened partition.
+
+ @param[in] Partition Pointer to the opened ext4 partition.
+
+ @return The first usable inode number (non-reserved).
+**/
+#define EXT4_FIRST_INODE_NR(Partition)
\
+ ((Partition->SuperBlock.s_rev_level == EXT4_GOOD_OLD_REV) ?
\
+ EXT4_GOOD_OLD_FIRST_INODE_NR :
\
+ Partition->SuperBlock.s_first_ino)
+
+/**
+ Checks inode number validity across superblock of the opened partition.
+
+ @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 == EXT4_ROOT_INODE_NR ||
\
+ (InodeNum >= EXT4_FIRST_INODE_NR(Partition) &&
\
+ 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,
diff --git a/Features/Ext4Pkg/Ext4Dxe/Directory.c
b/Features/Ext4Pkg/Ext4Dxe/Directory.c
index f80b1aacd459..2e9a58a7e329 100644
--- a/Features/Ext4Pkg/Ext4Dxe/Directory.c
+++ b/Features/Ext4Pkg/Ext4Dxe/Directory.c
@@ -164,6 +164,10 @@ Ext4RetrieveDirent (
if (Entry->inode == 0) {
BlockOffset += Entry->rec_len;
continue;
+ } else if (!EXT4_IS_VALID_INODE_NR (Partition, Entry->inode)) {
+ DEBUG ((DEBUG_ERROR, "[ext4] Ext4RetrieveDirent directory entry inode
number %u isn't valid\n", Entry->inode));
+ Status = EFI_VOLUME_CORRUPTED;
+ goto Out;
}
Status = Ext4GetUcs2DirentName (Entry, DirentUcs2Name);
@@ -510,6 +514,12 @@ Ext4ReadDir (
// (which we should not expose to ReadDir).
ShouldSkip = Entry.inode == 0 || Entry.name_len == 0 || IsDotOrDotDot;
+ if ((Entry.inode != 0) && !EXT4_IS_VALID_INODE_NR (Partition,
Entry.inode)) {
+ DEBUG ((DEBUG_ERROR, "[ext4] Ext4ReadDir directory entry inode number %u
isn't valid\n", Entry.inode));
+ Status = EFI_VOLUME_CORRUPTED;
+ goto Out;
+ }
+
if (ShouldSkip) {
Offset += Entry.rec_len;
continue;
--
2.39.0
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