CVE-2026-89495
Full vulnerability record from the local CVENow database.
Description
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 [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.
View original CVE JSON
{
"id": "CVE-2026-89495",
"sourceIdentifier": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
"published": "2026-09-11T20:19:31.493",
"lastModified": "2026-10-19T09:17:43.507",
"vulnStatus": "Received",
"cveTags": [],
"descriptions": [
{
"lang": "en",
"value": "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 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 [email protected] 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."
}
],
"affected": [
{
"source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
"affectedData": [
{
"vendor": "Linux",
"product": "Linux",
"defaultStatus": "unaffected",
"programFiles": [
"fs/ocfs2/dlm/dlmmaster.c"
],
"repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
"versions": [
{
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"lessThan": "e1288865b8ceac0dcd1009ecba43de961f13d5bd",
"versionType": "git",
"status": "affected"
},
{
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"status": "affected"
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"versionType": "git",
"status": "affected"
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{
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{
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},
{
"vendor": "Linux",
"product": "Linux",
"defaultStatus": "affected",
"programFiles": [
"fs/ocfs2/dlm/dlmmaster.c"
],
"repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
"versions": [
{
"version": "2.6.16",
"status": "affected"
},
{
"version": "0",
"lessThan": "2.6.16",
"versionType": "semver",
"status": "unaffected"
},
{
"version": "5.10.270",
"lessThanOrEqual": "5.10.*",
"versionType": "semver",
"status": "unaffected"
},
{
"version": "5.15.221",
"lessThanOrEqual": "5.15.*",
"versionType": "semver",
"status": "unaffected"
},
{
"version": "6.1.188",
"lessThanOrEqual": "6.1.*",
"versionType": "semver",
"status": "unaffected"
},
{
"version": "6.6.157",
"lessThanOrEqual": "6.6.*",
"versionType": "semver",
"status": "unaffected"
},
{
"version": "6.12.109",
"lessThanOrEqual": "6.12.*",
"versionType": "semver",
"status": "unaffected"
},
{
"version": "6.18.50",
"lessThanOrEqual": "6.18.*",
"versionType": "semver",
"status": "unaffected"
},
{
"version": "7.2.4",
"lessThanOrEqual": "7.2.*",
"versionType": "semver",
"status": "unaffected"
},
{
"version": "7.3",
"lessThanOrEqual": "*",
"versionType": "original_commit_for_fix",
"status": "unaffected"
}
]
}
]
}
],
"metrics": {
"cvssMetricV31": [
{
"source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
"type": "Secondary",
"cvssData": {
"version": "3.1",
"vectorString": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H",
"baseScore": 9.8,
"baseSeverity": "CRITICAL",
"attackVector": "NETWORK",
"attackComplexity": "LOW",
"privilegesRequired": "NONE",
"userInteraction": "NONE",
"scope": "UNCHANGED",
"confidentialityImpact": "HIGH",
"integrityImpact": "HIGH",
"availabilityImpact": "HIGH"
},
"exploitabilityScore": 3.9,
"impactScore": 5.9
}
]
},
"references": [
{
"url": "https://git.kernel.org/stable/c/006c96ea488eca2ef5155ec76038e0a4dbf65f0a",
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}