ocfs2: reject dinodes with non-canonical i_mode type

Overview

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().

Affected

• Linux >= b657c95c11088d77fc1bfc9c84d940f778bf9d12 < 2e3aac33988ef4e4170141db8e995693ea38357c
• Linux >= b657c95c11088d77fc1bfc9c84d940f778bf9d12 < fb024ea29f6cb1f01745e5f2e31646f3acb9aa6f
• Linux >= b657c95c11088d77fc1bfc9c84d940f778bf9d12 < 157d31ef45038d89cd19620105e082d43c8e41e0
• Linux >= b657c95c11088d77fc1bfc9c84d940f778bf9d12 < a5b555bcabbb0aff8745ad181768eaf9d964c1ee
• Linux >= b657c95c11088d77fc1bfc9c84d940f778bf9d12 < 82afe13558354390d8a592a5334d5f4fd72c0e5c
• Linux >= b657c95c11088d77fc1bfc9c84d940f778bf9d12 < 4db3b6a2a8ecf2a89d26a4090ace4072c6fad050
• Linux >= b657c95c11088d77fc1bfc9c84d940f778bf9d12 < b858f2d57cfc9d57ce61b86051d603dc0ebccd40
• Linux >= b657c95c11088d77fc1bfc9c84d940f778bf9d12 < 5366a017099c6a3c443be908a05f26fd72af12a1
• Linux 2.6.29

Remediation

Refer to the linked advisories for vendor-supplied fixes and affected version ranges.