CVE-2026-23140 bpf, test_run: Subtract size of xdp_frame from allowed metadata size

In the Linux kernel, the following vulnerability has been resolved: bpf, testrun: Subtract size of xdpframe from allowed metadata size The xdpframe structure takes up part of the XDP frame headroom, limiting the size of the metadata. However, in bpftestrun, we don't take this into account, which...