DEBIAN-CVE-2026-68082

In the Linux kernel, the following vulnerability has been resolved:  libceph: fix two unsafe bare decodes in decodelockers()  decodelockers() in clslockclient.c contains two bare decode operations that allow a malicious or compromised OSD to trigger slab-out-of-bounds reads:  1. cephdecode32(p) at the numlockers field has no preceding bounds    check. cephstartdecoding() accepts structlen=0 as valid -- the    internal cephdecodeneed(p, end, 0, bad) always passes -- so when an    OSD sends structlen=0, cephstartdecoding() returns success with    p == end. The immediately following bare cephdecode32(p) then reads    4 bytes past the validated buffer boundary. The garbage value is    passed directly to kzallocobjs() as the locker count.     The sibling function decodewatchers() in osdclient.c already uses    cephdecode32safe() after its own cephstartdecoding() call.    decodelockers() was the only site using the bare variant.  2. cephdecode8(p) after the decodelocker() loop has no preceding    bounds check. If an OSD crafts numlockers such that the loop    advances p exactly to end, the subsequent bare cephdecode8(p) reads    one byte past the validated buffer boundary. The result is passed    directly into *type, which is used as a lock type discriminator by    callers, giving an OSD-controlled one-byte OOB read with direct    influence over the lock type field.  Fix both by replacing bare operations with their safe variants:   cephdecode32(p) -> cephdecode32safe(p, end, numlockers,                                            errinval)   cephdecode8(p)  -> cephdecode8safe(p, end, *type,                                           errfreelockers)  The goto targets differ intentionally:   errinval: is a new label returning -EINVAL directly. It is used for   the pre-allocation failure path where lockers is not yet allocated   and must not be passed to cephfreelockers().    errfreelockers: is the existing label. It is used for the   post-allocation failure path where *lockers is allocated and must   be freed.  ret is set to -EINVAL before cephdecode8safe() so that errfreelockers returns the correct error code on bounds violation. Without this, errfreelockers would return a stale ret value (0 from the successful decodelocker() loop), silently swallowing the error.  -EINVAL is correct for both failure paths. The data received from the OSD is structurally malformed. -ENOMEM would misrepresent the failure class to callers and to stable@ backporters triaging error paths.  Attacker model: a malicious or compromised OSD in a multi-tenant Ceph deployment can trigger this against any kernel client that issues the lock.getinfo class method (e.g. during RBD exclusive lock acquisition).  [ idryomov: trim changelog, formatting ]