ntfs: move attribute payload before shrinking its record

Overview

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

ntfs: move attribute payload before shrinking its record

ntfs_new_attr_flags() resizes the non-resident attribute record before moving its name and mapping pairs to their shorter-header offsets when compression or sparse state is cleared.

Shrinking the record first moves the following attribute over the tail of the old record. The subsequent memmove() therefore copies bytes from that following attribute instead of the old mapping pairs. Re-enabling compression on an empty file persists those bytes as a malformed mapping pairs array, which ntfsck reports as a missing or invalid run length.

Move the payload before shrinking the record, while retaining the existing resize-before-move ordering when growing it.

Affected

• Linux >= 47503f989736d6c4c9f8bfca1c28d267473ccd4b < 7dc2c524608039d1b082a0087f7aa0751edd4ffb
• Linux >= 47503f989736d6c4c9f8bfca1c28d267473ccd4b < 0ab6dc1ac4601c8d79e5448a024daed6b0c5ef64
• Linux 7.1

Remediation

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