--- id: CVE-2026-89495 title: 'ocfs2: bound namelen in dlm_migrate_request_handler' summary: |- In 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 a… severity: critical cvss: 9.8 cvssVector: 'CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H' cvssSource: cna cwe: - CWE-120 vendor: Linux product: Linux affected: - >- Linux >= 6714d8e86bf443f6f7af50f9d432025649f091f5 < e1288865b8ceac0dcd1009ecba43de961f13d5bd - >- Linux >= 6714d8e86bf443f6f7af50f9d432025649f091f5 < aabc5d8388e6f8826345f0073455dbcaaaa6491d - >- Linux >= 6714d8e86bf443f6f7af50f9d432025649f091f5 < 006c96ea488eca2ef5155ec76038e0a4dbf65f0a - >- Linux >= 6714d8e86bf443f6f7af50f9d432025649f091f5 < 24989909d3413b44b104102caa6661b1e424ba0f - >- Linux >= 6714d8e86bf443f6f7af50f9d432025649f091f5 < f8658ee3327f73bd81c0bcd07cdeb5a8527fac98 - >- Linux >= 6714d8e86bf443f6f7af50f9d432025649f091f5 < de10cd3b062a5235af754925fcf49beb5a1109d4 - >- Linux >= 6714d8e86bf443f6f7af50f9d432025649f091f5 < 2487bea2098322669f0563baff53e797486b823f - >- Linux >= 6714d8e86bf443f6f7af50f9d432025649f091f5 < ea5b5609305a8437bc955a0834a530c12246d78f - Linux 2.6.16 published: '2026-09-11' updated: '2026-10-19' sourceUpdated: '2026-10-19T08:47:46.925Z' source: CVEORG sourceUrl: 'https://www.cve.org/CVERecord?id=CVE-2026-89495' references: - url: 'https://git.kernel.org/stable/c/e1288865b8ceac0dcd1009ecba43de961f13d5bd' - url: 'https://git.kernel.org/stable/c/aabc5d8388e6f8826345f0073455dbcaaaa6491d' - url: 'https://git.kernel.org/stable/c/006c96ea488eca2ef5155ec76038e0a4dbf65f0a' - url: 'https://git.kernel.org/stable/c/24989909d3413b44b104102caa6661b1e424ba0f' - url: 'https://git.kernel.org/stable/c/f8658ee3327f73bd81c0bcd07cdeb5a8527fac98' - url: 'https://git.kernel.org/stable/c/de10cd3b062a5235af754925fcf49beb5a1109d4' - url: 'https://git.kernel.org/stable/c/2487bea2098322669f0563baff53e797486b823f' - url: 'https://git.kernel.org/stable/c/ea5b5609305a8437bc955a0834a530c12246d78f' - url: >- https://security.access.redhat.com/data/csaf/v2/vex/2026/cve-2026-89495.json - url: 'https://access.redhat.com/security/cve/CVE-2026-89495' - url: 'https://bugzilla.redhat.com/show_bug.cgi?id=2532097' - url: 'https://www.cve.org/CVERecord?id=CVE-2026-89495' - url: 'https://nvd.nist.gov/vuln/detail/CVE-2026-89495' - url: >- https://git.kernel.org/pub/scm/linux/security/vulns.git/plain/cve/published/2026/CVE-2026-89495.mbox tags: - cve.org - csaf - vex - red-hat - score-dispute epss: 0.00714 epssPercentile: 0.53476 scores: cna: 9.8 vendor: 5.5 ingestedAt: '2026-09-14T15:23:07.452Z' --- ## Overview In 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 security@kernel.org 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. ## Affected - `Linux >= 6714d8e86bf443f6f7af50f9d432025649f091f5 < e1288865b8ceac0dcd1009ecba43de961f13d5bd` - `Linux >= 6714d8e86bf443f6f7af50f9d432025649f091f5 < aabc5d8388e6f8826345f0073455dbcaaaa6491d` - `Linux >= 6714d8e86bf443f6f7af50f9d432025649f091f5 < 006c96ea488eca2ef5155ec76038e0a4dbf65f0a` - `Linux >= 6714d8e86bf443f6f7af50f9d432025649f091f5 < 24989909d3413b44b104102caa6661b1e424ba0f` - `Linux >= 6714d8e86bf443f6f7af50f9d432025649f091f5 < f8658ee3327f73bd81c0bcd07cdeb5a8527fac98` - `Linux >= 6714d8e86bf443f6f7af50f9d432025649f091f5 < de10cd3b062a5235af754925fcf49beb5a1109d4` - `Linux >= 6714d8e86bf443f6f7af50f9d432025649f091f5 < 2487bea2098322669f0563baff53e797486b823f` - `Linux >= 6714d8e86bf443f6f7af50f9d432025649f091f5 < ea5b5609305a8437bc955a0834a530c12246d78f` - `Linux 2.6.16` ## Remediation Refer to the linked advisories for vendor-supplied fixes and affected version ranges. ## Vendor advisories - **Red Hat VEX** · Moderate · updated 2026-09-18 · [vex](https://security.access.redhat.com/data/csaf/v2/vex/2026/cve-2026-89495.json)