In the Linux kernel, the following vulnerability has been resolved: bpf: Fix a potential use-after-free of BTF object Refcounting in the checkpseudobtf_id() function is incorrect: the _checkpseudobtfid() function might get called with a zero refcounted btf. Fix this, and patch related code accordingly. v3: rephrase a comment (AI) v2: fix a refcount leak introduced in v1 (AI)