Bug 2532022 (CVE-2026-89494)

Summary: CVE-2026-89494 kernel: ocfs2: validate lengths in dlm_mig_lockres_handler
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 ocfs2, a component of the Linux kernel. A remote attacker, by sending a specially crafted Distributed Lock Manager (DLM) migration message, could exploit a lack of validation in the `dlm_mig_lockres_handler`. This flaw allows for an out-of-bounds write to the heap, potentially leading to arbitrary code execution. Additionally, an out-of-bounds read could cause a system panic, resulting in a denial of service.
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oVirt Team: --- RHEL 7.3 requirements from Atomic Host:
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Description OSIDB Bzimport 2026-09-11 20:02:25 UTC 
In the Linux kernel, the following vulnerability has been resolved:

ocfs2: validate lengths in dlm_mig_lockres_handler

A node receiving a DLM_MIG_LOCKRES message trusts several fields of the
peer-supplied dlm_migratable_lockres without validation.  num_locks and
lockname_len are bounded only on the sending side, and the message is
never checked to actually carry num_locks migratable_lock entries.  As a
result dlm_process_recovery_data() walks mres->ml[0..num_locks) past the
kmalloc(data_len) copy of the message (an out-of-bounds read that ends in
a BUG_ON panic), and dlm_init_lockres() copies lockname_len bytes into the
fixed 32-byte o2dlm_lockname slab object (a heap out-of-bounds write). 
Both are reachable by any node in the domain.

Validate these fields right after dlm_grab(), before anything uses them --
including the not-joined error path, which already prints mres->lockname
with the unbounded lockname_len as a %.*s precision.  Reject the message
unless lockname_len <= DLM_LOCKID_NAME_MAX, num_locks <=
DLM_MAX_MIGRATABLE_LOCKS (the bound the sender already asserts), and the
payload is large enough to hold the claimed locks.  Conforming recovery
and migration messages are unaffected.
Comment 1 Mauro Matteo Cascella 2026-09-14 08:48:04 UTC 
Upstream advisory:
https://git.kernel.org/pub/scm/linux/security/vulns.git/plain/cve/published/2026/CVE-2026-89494.mbox