Fix ringbuf reserve size mismatch in uprobe_finish_op

bpf_ringbuf_reserve() was using sizeof(struct op_v) but the code
copies a struct client_op_v into the reserved buffer. With the
acting[] array expansion this became a detectable OOB write caught
by the BPF verifier.

Signed-off-by: Seyeong Kim <seyeong.kim@canonical.com>

Author: xtrusia

src/radostrace.bpf.c

@@ -320,7 +320,7 @@ int uprobe_finish_op(struct pt_regs *ctx) {
   opv->finish_stamp = bpf_ktime_get_boot_ns();
   opv->pid = get_pid();
   // submit to ringbuf
-  struct client_op_v *e = bpf_ringbuf_reserve(&rb, sizeof(struct op_v), 0);
+  struct client_op_v *e = bpf_ringbuf_reserve(&rb, sizeof(struct client_op_v), 0);
   if (NULL == e) {
     return 0;
   }