bpf: making bpf_prog_test run aware of possible data_end ptr change

after introduction of bpf_xdp_adjust_tail helper packet length
could be changed not only if xdp->data pointer has been changed
but xdp->data_end as well. making bpf_prog_test_run aware of this
possibility

Signed-off-by: Nikita V. Shirokov <tehnerd@tehnerd.com>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>

net/bpf/test_run.c

@@ -170,7 +170,8 @@ int bpf_prog_test_run_xdp(struct bpf_prog *prog, const union bpf_attr *kattr,
 	xdp.rxq = &rxqueue->xdp_rxq;
 
 	retval = bpf_test_run(prog, &xdp, repeat, &duration);
-	if (xdp.data != data + XDP_PACKET_HEADROOM + NET_IP_ALIGN)
+	if (xdp.data != data + XDP_PACKET_HEADROOM + NET_IP_ALIGN ||
+	    xdp.data_end != xdp.data + size)
 		size = xdp.data_end - xdp.data;
 	ret = bpf_test_finish(kattr, uattr, xdp.data, size, retval, duration);
 	kfree(data);