selftest/bpf/benchs: Add benchmark for sockmap usage

Hello Jiayuan Chen,

Commit 7b2fa44de5e7 ("selftest/bpf/benchs: Add benchmark for sockmap usage") from Apr 7, 2025 (linux-next), leads to the following Smatch static checker warning:

tools/testing/selftests/bpf/benchs/bench_sockmap.c:129 bench_sockmap_prog_destroy()
error: buffer overflow 'ctx.fds' 5 <= 19

tools/testing/selftests/bpf/benchs/bench_sockmap.c

    123 static void bench_sockmap_prog_destroy(void)
    124 {
    125         int i;
    126 
    127         for (i = 0; i < sizeof(ctx.fds); i++) {
                                ^^^^^^^^^^^^^^^

This should be ARRAY_SIZE(ctx.fds) otherwise it's a buffer overflow.

    128                 if (ctx.fds[0] > 0)
                            ^^^^^^^^^^

Instead of .fds[0] it should be .fds[i], right?

--> 129                         close(ctx.fds[i]);
    130         }
    131 
    132         bench_sockmap_prog__destroy(ctx.skel);
    133 }

regards,
dan carpenter