CVE-2026-68157: NULL Pointer Dereference

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

libceph: guard missing CRUSH type name lookup

Localized read selection can walk a parent bucket whose name exists in the CRUSH map while its type has no matching entry in type_names. get_immediate_parent() then dereferences a NULL type_cn and passes an invalid pointer into strcmp(), causing a null-ptr-deref.

Skip such malformed parent buckets unless both the bucket name and type name metadata are present. This keeps malformed hierarchy data from crashing locality lookup and safely falls back to "not local".

[ idryomov: add WARN_ON_ONCE ]