ocfs2: bound namelen in dlm_migrate_request_handler

MITRE NVD CVE.ORG JSON API

Summary

CVECVE-2026-89495
StatePUBLISHED
AssignerLinux
Source PriorityCVE Program / NVD first with legacy fallback
Published2026-09-11 20:19:31 UTC
Updated2026-09-11 20:19:31 UTC
DescriptionIn the Linux kernel, the following vulnerability has been resolved: ocfs2: bound namelen in dlm_migrate_request_handler Patch series "ocfs2/dlm: bound peer-controlled lengths in the o2dlm". The o2dlm receive handlers trust u8 length and count fields from the wire without bounding them, so a node in a DLM domain can corrupt or panic any other node with a malformed message. Three defects: - dlm_migrate_request_handler() passes migrate->namelen unchecked to dlm_init_mle(), which memcpy()s it into the 32-byte mname[] of an o2dlm_mle slab object: a heap out-of-bounds write of up to ~215 attacker-controlled bytes. - dlm_mig_lockres_handler() passes mres->lockname_len unchecked to dlm_init_lockres(), which memcpy()s it into the 32-byte o2dlm_lockname slab object: a heap out-of-bounds write of up to ~223 bytes. - the same handler trusts mres->num_locks without checking that the message is large enough to hold that many entries, so dlm_process_recovery_data() walks mres->ml[] past the kmalloc(data_len) copy and trips a BUG_ON (an out-of-bounds read ending in a panic). The other o2dlm receive handlers already reject an oversized name; the migration and recovery handlers have omitted it since the DLM was added (see the Fixes tags). Patch 1 bounds namelen; patch 2 validates lockname_len, num_locks, and the payload size. Conforming recovery and migration traffic is unaffected. o2net authenticates peers only by the DLM domain key, so any node that has joined the domain -- including a compromised or malicious member -- can send these messages. There is no local trigger; the attacker must already be a member of the cluster. Each sink was confirmed under KASAN with an out-of-tree module mirroring it exactly -- a kmem_cache/kmalloc of the real destination size, then the same unclamped memcpy/loop: slab-out-of-bounds Write for the two writes, Read for the recovery walk, and a panic. A userspace AddressSanitizer build faults identically under -m32 and -m64. Scrubbed logs are available on request. I reported this privately to [email protected] and the ocfs2 maintainers on 2026-06-20; with no response after the standard embargo period I am posting the fix publicly. I have no embargo requirement. This patch (of 2): A node receiving a DLM_MIGRATE_REQUEST message trusts the peer-supplied name length (migrate->namelen) without bounding it. dlm_init_mle() then copies that many bytes into the fixed DLM_LOCKID_NAME_MAX-byte mname[] array of an o2dlm_mle slab object, so a malformed message from a cluster peer overflows the slab object by up to ~215 bytes: a heap out-of-bounds write of attacker-controlled data, reachable by any node in the domain. Reject an oversized name, the way dlm_master_request_handler() and the other o2dlm receive handlers already do; the migration handler omits the check entirely. Conforming messages are unaffected.

Vendor Declared Affected Products

SourceVendorProductVersionPlatforms
CNA Linux Linux affected 6714d8e86bf443f6f7af50f9d432025649f091f5 f8658ee3327f73bd81c0bcd07cdeb5a8527fac98 git Not specified
CNA Linux Linux affected 6714d8e86bf443f6f7af50f9d432025649f091f5 de10cd3b062a5235af754925fcf49beb5a1109d4 git Not specified
CNA Linux Linux affected 6714d8e86bf443f6f7af50f9d432025649f091f5 2487bea2098322669f0563baff53e797486b823f git Not specified
CNA Linux Linux affected 6714d8e86bf443f6f7af50f9d432025649f091f5 ea5b5609305a8437bc955a0834a530c12246d78f git Not specified
CNA Linux Linux affected 2.6.16 Not specified
CNA Linux Linux unaffected 2.6.16 semver Not specified
CNA Linux Linux unaffected 6.12.109 6.12.* semver Not specified
CNA Linux Linux unaffected 6.18.50 6.18.* semver Not specified
CNA Linux Linux unaffected 7.2.4 7.2.* semver Not specified
CNA Linux Linux unaffected 7.3-rc1 * original_commit_for_fix Not specified

References

ReferenceSourceLinkTags
git.kernel.org/stable/c/de10cd3b062a5235af754925fcf49beb5a1109d4 416baaa9-dc9f-4396-8d5f-8c081fb06d67 git.kernel.org
git.kernel.org/stable/c/f8658ee3327f73bd81c0bcd07cdeb5a8527fac98 416baaa9-dc9f-4396-8d5f-8c081fb06d67 git.kernel.org
git.kernel.org/stable/c/2487bea2098322669f0563baff53e797486b823f 416baaa9-dc9f-4396-8d5f-8c081fb06d67 git.kernel.org
git.kernel.org/stable/c/ea5b5609305a8437bc955a0834a530c12246d78f 416baaa9-dc9f-4396-8d5f-8c081fb06d67 git.kernel.org
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