ntfs: do not read an index block outside $INDEX_ALLOCATION

A directory whose $INDEX_ROOT has a child node but whose
$INDEX_ALLOCATION is missing or damaged gets an empty index inode from
ntfs_read_locked_index_inode(): size 0 and not non-resident.
ntfs_lookup_inode_by_name() still follows the child node and reads a
folio from that inode while it holds the mft record lock of the
directory.

Since the resident iomap read started to take base_ni->mrec_lock, that
read waits for a lock the caller already holds:

  INFO: task init:1 is blocked on a mutex likely owned by task init:1.
   __mutex_lock
   __ntfs_read_iomap_begin
   ntfs_read_iomap_next
   iomap_read_folio
   ntfs_read_folio
   ntfs_lookup_inode_by_name
   ntfs_lookup

The task never returns, and neither does anything else that needs the
directory's mft record.

It takes one corrupted byte on an image from mkntfs: change the first
byte of the type of the $INDEX_ALLOCATION attribute header of a
directory with index blocks from 0xa0 to 0x00. The first lookup in that
directory hangs.

Check that the index inode is non-resident and that the vcn lies inside
it before every index block read, and fail with -EIO otherwise. This
also rejects a negative vcn, which was only checked on later descents.

Fixes: d9e00c457d4a ("ntfs: serialize resident iomap reads with mrec_lock")
Cc: stable@vger.kernel.org # v7.3+
Signed-off-by: Wahid Khan <wahidzk0091@gmail.com>
Signed-off-by: Namjae Jeon <linkinjeon@kernel.org>

0 files changed, 0 insertions, 0 deletions