CVE-2026-89574

/// Technical description

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

dm array: validate array block headers on read

array_block_check() validates blocknr and csum and nothing else, while

node_check(), next to it, has bounded the structural fields since both

were written. dm_array_cursor_next() takes its loop bound from the

on-disk nr_entries and element_at() is unguarded pointer arithmetic, so

a count larger than the block holds keeps the cursor in one block while

the index grows past it and the read walks off the dm-bufio buffer --

dm_cache_load_mappings() drives it once per cache block at activation.

Check the header against itself: reject a zero value_size, require

max_entries to equal calc_max_entries() for that value_size and block

size, and require nr_entries to fit. Equality rather than an upper bound,

since a count below the real capacity trips BUG_ON() in fill_ablock() and

trim_ablock(). Metadata dm-array writes satisfies all three.

/// Remediation

Check the references section for vendor advisories, patches, and mitigation guidance. If immediate patching is not possible, review the CVSS vector to understand the attack surface and apply compensating controls such as network segmentation or access restrictions.

/// References