CVE-2026-89611: Undefined Security Weakness

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.