CVE-2026-43304: Undefined Security Weakness

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

libceph: define and enforce CEPH_MAX_KEY_LEN

When decoding the key, verify that the key material would fit into a fixed-size buffer in process_auth_done() and generally has a sane length.

The new CEPH_MAX_KEY_LEN check replaces the existing check for a key with no key material which is a) not universal since CEPH_CRYPTO_NONE has to be excluded and b) doesn't provide much value since a smaller than needed key is just as invalid as no key -- this has to be handled elsewhere anyway.