REDHAT-BUG-2334548: Medium severity Linux Foundation Linux Kernel vulnerability

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

bpf: Fix UAF via mismatching bpfprog/attachment RCU flavors

Uprobes always use bpfprogrunarrayuprobe() under tasks-trace-RCU protection. But it is possible to attach a non-sleepable BPF program to a uprobe, and non-sleepable BPF programs are freed via normal RCU (see bpfprogputnoref()). This leads to UAF of the bpfprog because a normal RCU grace period does not imply a tasks-trace-RCU grace period.

Fix it by explicitly waiting for a tasks-trace-RCU grace period after removing the attachment of a bpfprog to a perfevent.