CVE-2026-43009 bpf: Fix incorrect pruning due to atomic fetch precision tracking

In the Linux kernel, the following vulnerability has been resolved: bpf: Fix incorrect pruning due to atomic fetch precision tracking When backtrackinsn encounters a BPFSTX instruction with BPFATOMIC and BPFFETCH, the src register or r0 for BPFCMPXCHG also acts as a destination, thus receiving th...