In the Linux kernel, the following vulnerability has been resolved:
ocfs2: reject dinodes with non-canonical i_mode type
Patch series “ocfs2: harden inode validators against forged metadata”, v2.
This series adds three structural checks to OCFS2 dinode validation so
malformed on-disk fields are rejected before ocfs2_populate_inode() copies
them into the in-core inode.
The checks cover:
– i_mode values whose type bits do not name a canonical POSIX file
type;
– non-device dinodes whose id1.dev1.i_rdev field is non-zero; and
– non-inline dinodes that claim non-zero i_size while i_clusters is
zero, covering directories unconditionally and regular files on
non-sparse volumes.
The normal read path reports these through ocfs2_error(), matching the
existing suballoc-slot, inline-data, chain-list, and refcount checks. The
online filecheck path uses the same structural predicates but keeps its
own reporting contract, returning OCFS2_FILECHECK_ERR_INVALIDINO instead
of calling ocfs2_error().
This patch (of 3):
ocfs2_validate_inode_block() currently accepts any non-zero i_mode value.
ocfs2_populate_inode() then copies that mode verbatim into inode->i_mode
and dispatches on i_mode & S_IFMT to the file/dir/symlink/special_file
iops; an unrecognised type falls through to ocfs2_special_file_iops and
init_special_inode().
Reject dinodes whose type bits do not name one of the seven canonical
POSIX file types. Use fs_umode_to_ftype(), the same generic file-type
conversion helper OCFS2 already uses for directory entries, so the
accepted inode type set matches the kernel file-type vocabulary instead of
open-coding a local switch.
Apply the same structural check to the online filecheck read path.
filecheck keeps its own error namespace, so it reports malformed i_mode
through the filecheck logger and OCFS2_FILECHECK_ERR_INVALIDINO instead of
calling ocfs2_error(), but it must not allow a malformed dinode to proceed
into ocfs2_populate_inode().
