Description
In the Linux kernel, the following vulnerability has been resolved:

libceph: fix multiple unsafe decodes in decode_locker()

decode_locker() in cls_lock_client.c contains three unsafe decode
operations that allow a malicious or compromised OSD to trigger
slab-out-of-bounds reads:

1. ceph_decode_copy() at the locker_id_t name field has no preceding
bounds check. With p == end after ceph_start_decoding() accepts
struct_len=0, this reads sizeof(ceph_entity_name) = 9 bytes past
the validated buffer boundary.

2. *p += sizeof(struct ceph_timespec) after the locker_info_t header
is an unchecked pointer advance. A malicious OSD can position p
past end, causing all subsequent _safe checks to pass against a
bogus boundary.

3. len = ceph_decode_32(p) has no preceding bounds check, and the
immediately following *p += len is uncapped. A malicious OSD can
send len=0xffffffff, advancing p gigabytes past end and escaping
the decode window entirely.

Fix all three by replacing bare operations with their safe variants:
ceph_decode_copy -> ceph_decode_copy_safe
*p += sizeof(...) -> ceph_decode_skip_n
ceph_decode_32(p) -> ceph_decode_32_safe
*p += len -> ceph_decode_skip_n

A new label is added to return -EINVAL on any bounds violation.
-EINVAL is appropriate here: the data received from the OSD
is structurally malformed, which is an invalid argument to the decode
contract regardless of whether the caller or the wire is at fault.

Attacker model: a malicious or compromised OSD in a multi-tenant Ceph
deployment can trigger this against any kernel client that issues the
lock.get_info class method (e.g. during RBD exclusive lock acquisition)
without any further privileges beyond OSD session establishment.

[ idryomov: use ceph_decode_skip_string() to skip description, trim
changelog ]
Published: 2026-08-26
Score: n/a
EPSS: n/a
KEV: No
Impact: n/a
Action: n/a
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Remediation

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History

Wed, 26 Aug 2026 17:15:00 +0000

Type Values Removed Values Added
Weaknesses CWE-125

Wed, 26 Aug 2026 14:45:00 +0000

Type Values Removed Values Added
Description In the Linux kernel, the following vulnerability has been resolved: libceph: fix multiple unsafe decodes in decode_locker() decode_locker() in cls_lock_client.c contains three unsafe decode operations that allow a malicious or compromised OSD to trigger slab-out-of-bounds reads: 1. ceph_decode_copy() at the locker_id_t name field has no preceding bounds check. With p == end after ceph_start_decoding() accepts struct_len=0, this reads sizeof(ceph_entity_name) = 9 bytes past the validated buffer boundary. 2. *p += sizeof(struct ceph_timespec) after the locker_info_t header is an unchecked pointer advance. A malicious OSD can position p past end, causing all subsequent _safe checks to pass against a bogus boundary. 3. len = ceph_decode_32(p) has no preceding bounds check, and the immediately following *p += len is uncapped. A malicious OSD can send len=0xffffffff, advancing p gigabytes past end and escaping the decode window entirely. Fix all three by replacing bare operations with their safe variants: ceph_decode_copy -> ceph_decode_copy_safe *p += sizeof(...) -> ceph_decode_skip_n ceph_decode_32(p) -> ceph_decode_32_safe *p += len -> ceph_decode_skip_n A new label is added to return -EINVAL on any bounds violation. -EINVAL is appropriate here: the data received from the OSD is structurally malformed, which is an invalid argument to the decode contract regardless of whether the caller or the wire is at fault. Attacker model: a malicious or compromised OSD in a multi-tenant Ceph deployment can trigger this against any kernel client that issues the lock.get_info class method (e.g. during RBD exclusive lock acquisition) without any further privileges beyond OSD session establishment. [ idryomov: use ceph_decode_skip_string() to skip description, trim changelog ]
Title libceph: fix multiple unsafe decodes in decode_locker()
First Time appeared Linux
Linux linux Kernel
CPEs cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*
Vendors & Products Linux
Linux linux Kernel
References

Subscriptions

Linux Linux Kernel
cve-icon MITRE

Status: PUBLISHED

Assigner: Linux

Published:

Updated: 2026-08-26T14:37:26.572Z

Reserved: 2026-08-26T14:34:25.767Z

Link: CVE-2026-80561

cve-icon Vulnrichment

No data.

cve-icon NVD

Status : Received

Published: 2026-08-26T15:17:11.007

Modified: 2026-08-26T15:17:11.007

Link: CVE-2026-80561

cve-icon Redhat

No data.

cve-icon OpenCVE Enrichment

Updated: 2026-08-26T19:15:10Z

Weaknesses