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 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.
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.
Analysis
Analysis and contextual insights are available on OpenCVE Cloud.
Default status is the baseline for the product, each version can override it (e.g. patched versions marked unaffected).
| Vendor | Product | Default status | Versions | |||||||||||||||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Linux | Linux | unaffected |
|
|||||||||||||||||||||
| Linux | Linux | affected |
|
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No data available yet.
Remediation
No vendor fix or workaround currently provided.
Additional remediation guidance may be available on OpenCVE Cloud.
Tracking
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Advisories
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References
History
Sat, 12 Sep 2026 00:15:00 +0000
| Type | Values Removed | Values Added |
|---|---|---|
| Weaknesses | CWE-120 | |
| References |
| |
| Metrics |
threat_severity
|
cvssV3_1
|
Fri, 11 Sep 2026 23:45:00 +0000
| Type | Values Removed | Values Added |
|---|---|---|
| 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 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. | |
| Title | ocfs2: bound namelen in dlm_migrate_request_handler | |
| First Time appeared |
Linux
Linux linux Kernel |
|
| CPEs | cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:* | |
| Vendors & Products |
Linux
Linux linux Kernel |
|
| References |
|
MITRE
Status: PUBLISHED
Assigner: Linux
Published:
Updated: 2026-09-11T19:43:46.107Z
Reserved: 2026-09-11T19:38:34.714Z
Link: CVE-2026-89495
Vulnrichment
No data.
NVD
Status : Received
Published: 2026-09-11T20:19:31.493
Modified: 2026-09-11T20:19:31.493
Link: CVE-2026-89495
Redhat
OpenCVE Enrichment
Updated: 2026-09-12T04:00:07Z
Weaknesses
-
CWE-120
Buffer Copy without Checking Size of Input ('Classic Buffer Overflow')