Bug 2532210 (CVE-2026-89573)

Summary: CVE-2026-89573 kernel: dm array: reject an array block whose value size is not the caller's
Product: [Other] Security Response Reporter: OSIDB Bzimport <bzimport>
Component: vulnerabilityAssignee: Product Security DevOps Team <prodsec-dev>
Status: NEW --- QA Contact:
Severity: medium Docs Contact:
Priority: medium    
Version: unspecifiedCC: akhatavk, aos-team-art-private, asdas, dpaolell, jdelft, jupierce, lgarciaa, mbiarnes, ppalepu, ppostler, prdhamdh, rhel-process-autobot, sghai, sidsharm, suppawar, vlaad, watson-tool-maintainers
Target Milestone: ---Keywords: Security
Target Release: ---   
Hardware: All   
OS: Linux   
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A flaw was found in the Linux kernel's device mapper (dm) array component. A local attacker could exploit this vulnerability by providing specially crafted metadata. This crafted metadata causes the system to misinterpret the size of data blocks, leading to an out-of-bounds read. This memory corruption could result in system instability or a denial of service.
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Embargoed:

Description OSIDB Bzimport 2026-09-11 21:23:43 UTC 
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.
Comment 1 Keith Grant 2026-09-18 16:31:28 UTC 
Upstream advisory:
https://git.kernel.org/pub/scm/linux/security/vulns.git/plain/cve/published/2026/CVE-2026-89573.mbox