Executive brief
The OCFS2 filesystem driver in the Linux kernel validates inode structures to detect malformed metadata. This fix adds validation to reject non-inline directory and regular file inodes that claim a file size but have no allocated storage clusters—a structurally impossible state. An attacker with crafted filesystem images could trigger filesystem errors during reads, potentially causing denial of service or triggering unintended code paths.
Technical details
This is a validation hardening patch, not a classic vulnerability disclosure. The OCFS2 filesystem was accepting non-inline dinodes with non-zero i_size and zero i_clusters, a logically impossible state: the extent map declares no allocated storage yet the size field claims content exists. The fix introduces a shared validation predicate `ocfs2_dinode_has_size_without_clusters()` that rejects such malformed inodes during both normal inode reads and online filecheck operations. The check exempts sparse-alloc volumes (where zero clusters with non-zero size is legitimate), system inodes, and inline-data dinodes. A malicious or corrupted filesystem image could cause repeated I/O failures or unexpected behavior when such inodes are encountered. The patch is merged into the Linux stable tree and available in kernel versions 4.x through 7.x.
Affected products
- Linux Linux kernel all versions (patch applied to stable branches from 4.x through 7.x)
Timeline
- 2026-05-19: other: Patch authored
- 2026-07-24: patched: Merged into stable tree
- 2026-08-15: disclosed