CVE-2026-89573

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

dm array: reject an array block whose value size is not the caller's

array_block_check() can only compare the header against itself, so a block

with value_size 4 and max_entries 1018 is internally consistent and passes.

dm-cache keeps two arrays -- mappings at 8 bytes and hints at 4 -- and the

roots for both live in the superblock. Point the mappings root at a hint

block and __load_mappings() walks it through an info whose value size is 8,

so element_at() strides 8 bytes over 4-byte entries and reaches offset 8160

of a 4096-byte block.

get_ablock() and __shadow_ablock() are the two places that hold the block

and the caller at once. Reject there when the two value sizes disagree.

Arrays only ever read their own blocks, so this fires on crafted metadata

only.