CVE-2026-80561

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

libceph: fix multiple unsafe decodes in decode_locker()

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

1. cephdecodecopy() at the lockeridt name field has no preceding bounds check. With p == end after cephstartdecoding() accepts structlen=0, this reads sizeof(cephentity_name) = 9 bytes past the validated buffer boundary.

2. *p += sizeof(struct cephtimespec) after the lockerinfo_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 = cephdecode32(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: cephdecodecopy -> cephdecodecopysafe *p += sizeof(...) -> cephdecodeskipn cephdecode32(p) -> cephdecode32safe *p += len -> cephdecodeskipn

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 cephdecodeskip_string() to skip description, trim changelog ]