ntfs: validate non-resident attribute offsets

Overview

In the Linux kernel, the following vulnerability has been resolved:

ntfs: validate non-resident attribute offsets

ntfs_attr_update_meta() shifts the attribute name when converting between non-sparse and sparse attributes. Converting to sparse also adds the compressed_size field before the name and mapping pairs, requiring eight additional bytes in the attribute record.

However, the validator does not check that name_offset is within safe boundaries for these operations or that the additional space is available. A malicious MFT record could set name_offset such that:

1. The name is positioned at the very end of a non-sparse attribute. Converting to sparse would shift the name forward by 8 bytes, writing beyond the attribute boundary.

2. The name overlaps with the mapping pairs, causing corruption during conversion.

Add validation to ensure:

• For named attributes, name_offset is within valid bounds
• Name does not extend beyond the attribute or overlap with mapping pairs
• For non-sparse, non-compressed attributes, eight bytes are available after mapping_pairs_offset for the compressed_size field

The space check also covers unnamed attributes, for which name_offset = 0 is valid and no name range needs to be checked.

Affected

• Linux >= 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 < cd7b3dc7557faadeea626034e3bac68a449851ef
• Linux >= 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 < a83e82b0ec3ae523028e24813f23f18b43e8fc1c
• Linux < 7.2.4
• Linux (all versions)

Remediation

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

Vendor advisories

• Red Hat VEX · Moderate · updated 2026-09-18 · vex