CVE-2024-35860 bpf: support deferring bpf_link dealloc to after RCU grace period

In the Linux kernel, the following vulnerability has been resolved: bpf: support deferring bpflink dealloc to after RCU grace period BPF link for some program types is passed as a "context" which can be used by those BPF programs to look up additional information. E.g., for multi-kprobes and...

CVE-2024-35860

CVE-2024-35860 affects the Linux kernel. The issue is a runtime dependency in bpf_link where, after the link’s refcnt hits zero, active BPF programs may still access link data. The patch adds two deallocation callbacks (synchronous and deferred) and makes bpf_link_free() schedule deallocation aft...