{"id":"CVE-2026-89495","title":"ocfs2: bound namelen in dlm_migrate_request_handler","summary":"In the Linux kernel, the following vulnerability has been resolved:\n\nocfs2: bound namelen in dlm_migrate_request_handler\n\nPatch series \"ocfs2/dlm: bound peer-controlled lengths in the o2dlm\".\n\nThe 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","slug":"CVE-2026-89495","body":"## Overview\n\nIn the Linux kernel, the following vulnerability has been resolved:\n\nocfs2: bound namelen in dlm_migrate_request_handler\n\nPatch series \"ocfs2/dlm: bound peer-controlled lengths in the o2dlm\".\n\nThe o2dlm receive handlers trust u8 length and count fields from the wire\nwithout bounding them, so a node in a DLM domain can corrupt or panic any\nother node with a malformed message.  Three defects:\n\n  - dlm_migrate_request_handler() passes migrate->namelen unchecked to\n    dlm_init_mle(), which memcpy()s it into the 32-byte mname[] of an\n    o2dlm_mle slab object: a heap out-of-bounds write of up to ~215\n    attacker-controlled bytes.\n\n  - dlm_mig_lockres_handler() passes mres->lockname_len unchecked to\n    dlm_init_lockres(), which memcpy()s it into the 32-byte o2dlm_lockname\n    slab object: a heap out-of-bounds write of up to ~223 bytes.\n\n  - the same handler trusts mres->num_locks without checking that the\n    message is large enough to hold that many entries, so\n    dlm_process_recovery_data() walks mres->ml[] past the kmalloc(data_len)\n    copy and trips a BUG_ON (an out-of-bounds read ending in a panic).\n\nThe other o2dlm receive handlers already reject an oversized name; the\nmigration and recovery handlers have omitted it since the DLM was added\n(see the Fixes tags).  Patch 1 bounds namelen; patch 2 validates\nlockname_len, num_locks, and the payload size.  Conforming recovery and\nmigration traffic is unaffected.\n\no2net authenticates peers only by the DLM domain key, so any node that has\njoined the domain -- including a compromised or malicious member -- can\nsend these messages.  There is no local trigger; the attacker must already\nbe a member of the cluster.\n\nEach sink was confirmed under KASAN with an out-of-tree module mirroring\nit exactly -- a kmem_cache/kmalloc of the real destination size, then the\nsame unclamped memcpy/loop: slab-out-of-bounds Write for the two writes,\nRead for the recovery walk, and a panic.  A userspace AddressSanitizer\nbuild faults identically under -m32 and -m64.  Scrubbed logs are available\non request.\n\nI reported this privately to security@kernel.org and the ocfs2 maintainers\non 2026-06-20; with no response after the standard embargo period I am\nposting the fix publicly.  I have no embargo requirement.\n\n\nThis patch (of 2):\n\nA node receiving a DLM_MIGRATE_REQUEST message trusts the peer-supplied\nname length (migrate->namelen) without bounding it.  dlm_init_mle() then\ncopies that many bytes into the fixed DLM_LOCKID_NAME_MAX-byte mname[]\narray of an o2dlm_mle slab object, so a malformed message from a cluster\npeer overflows the slab object by up to ~215 bytes: a heap out-of-bounds\nwrite of attacker-controlled data, reachable by any node in the domain.\n\nReject an oversized name, the way dlm_master_request_handler() and the\nother o2dlm receive handlers already do; the migration handler omits the\ncheck entirely.  Conforming messages are unaffected.\n\n## Affected\n\n- `Linux >= 6714d8e86bf443f6f7af50f9d432025649f091f5 < e1288865b8ceac0dcd1009ecba43de961f13d5bd`\n- `Linux >= 6714d8e86bf443f6f7af50f9d432025649f091f5 < aabc5d8388e6f8826345f0073455dbcaaaa6491d`\n- `Linux >= 6714d8e86bf443f6f7af50f9d432025649f091f5 < 006c96ea488eca2ef5155ec76038e0a4dbf65f0a`\n- `Linux >= 6714d8e86bf443f6f7af50f9d432025649f091f5 < 24989909d3413b44b104102caa6661b1e424ba0f`\n- `Linux >= 6714d8e86bf443f6f7af50f9d432025649f091f5 < f8658ee3327f73bd81c0bcd07cdeb5a8527fac98`\n- `Linux >= 6714d8e86bf443f6f7af50f9d432025649f091f5 < de10cd3b062a5235af754925fcf49beb5a1109d4`\n- `Linux >= 6714d8e86bf443f6f7af50f9d432025649f091f5 < 2487bea2098322669f0563baff53e797486b823f`\n- `Linux >= 6714d8e86bf443f6f7af50f9d432025649f091f5 < ea5b5609305a8437bc955a0834a530c12246d78f`\n- `Linux 2.6.16`\n\n## Remediation\n\nRefer to the linked advisories for vendor-supplied fixes and affected version ranges.\n\n## Vendor advisories\n\n- **Red Hat VEX** · Moderate · updated 2026-09-18 · [vex](https://security.access.redhat.com/data/csaf/v2/vex/2026/cve-2026-89495.json)","depth":"midnight","depthScore":54,"depthScoreParts":{"impact":53.9,"likelihood":0.1,"exploitation":0,"ransomware":0},"changes":[{"seq":224734,"id":"CVE-2026-89495","ts":1792401509569,"field":"cvss","old":"5.5","new":"9.8"},{"seq":224733,"id":"CVE-2026-89495","ts":1792401509569,"field":"severity","old":"medium","new":"critical"},{"seq":206948,"id":"CVE-2026-89495","ts":1789749713406,"field":"cvss","old":"9.8","new":"5.5"},{"seq":206947,"id":"CVE-2026-89495","ts":1789749713406,"field":"severity","old":"critical","new":"medium"},{"seq":198006,"id":"CVE-2026-89495","ts":1789384321344,"field":"cvss","old":"6.4","new":"9.8"},{"seq":198005,"id":"CVE-2026-89495","ts":1789384321344,"field":"severity","old":"medium","new":"critical"},{"seq":183783,"id":"CVE-2026-89495","ts":1789356677369,"field":"cvss","old":"9.8","new":"6.4"},{"seq":183782,"id":"CVE-2026-89495","ts":1789356677369,"field":"severity","old":"critical","new":"medium"},{"seq":153284,"id":"CVE-2026-89495","ts":1789285349881,"field":"cvss","old":null,"new":"9.8"},{"seq":153283,"id":"CVE-2026-89495","ts":1789285349881,"field":"severity","old":"none","new":"critical"},{"seq":147782,"id":"CVE-2026-89495","ts":1789270212268,"field":"cvss","old":null,"new":"6.4"},{"seq":147781,"id":"CVE-2026-89495","ts":1789270212268,"field":"severity","old":"none","new":"medium"},{"seq":109530,"id":"CVE-2026-89495","ts":1789183732301,"field":"cvss","old":null,"new":"6.4"},{"seq":109529,"id":"CVE-2026-89495","ts":1789183732301,"field":"severity","old":"none","new":"medium"}]}