selftests/bpf: Add test for abnormal cnt during multi-kprobe attachment

If an abnormally huge cnt is used for multi-kprobes attachment, the
following warning will be reported:

  ------------[ cut here ]------------
  WARNING: CPU: 1 PID: 392 at mm/util.c:632 kvmalloc_node+0xd9/0xe0
  Modules linked in: bpf_testmod(O)
  CPU: 1 PID: 392 Comm: test_progs Tainted: G ...... 6.7.0-rc3+ #32
  Hardware name: QEMU Standard PC (i440FX + PIIX, 1996)
  ......
  RIP: 0010:kvmalloc_node+0xd9/0xe0
   ? __warn+0x89/0x150
   ? kvmalloc_node+0xd9/0xe0
   bpf_kprobe_multi_link_attach+0x87/0x670
   __sys_bpf+0x2a28/0x2bc0
   __x64_sys_bpf+0x1a/0x30
   do_syscall_64+0x36/0xb0
   entry_SYSCALL_64_after_hwframe+0x6e/0x76
  RIP: 0033:0x7fbe067f0e0d
  ......
   </TASK>
  ---[ end trace 0000000000000000 ]---

So add a test to ensure the warning is fixed.

Signed-off-by: Hou Tao <houtao1@huawei.com>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Acked-by: Jiri Olsa <jolsa@kernel.org>
Acked-by: Andrii Nakryiko <andrii@kernel.org>
Link: https://lore.kernel.org/bpf/20231215100708.2265609-6-houtao@huaweicloud.com

diff --git a/tools/testing/selftests/bpf/prog_tests/kprobe_multi_test.c b/tools/testing/selftests/bpf/prog_tests/kprobe_multi_test.c
index 6079611b5df4b23fd244d17a4270fca5712d6af2..05000810e28ea9331f27cd18790a7ee476351b60 100644 (file)
--- a/tools/testing/selftests/bpf/prog_tests/kprobe_multi_test.c
+++ b/tools/testing/selftests/bpf/prog_tests/kprobe_multi_test.c
@@ -306,6 +306,21 @@ static void test_attach_api_fails(void)
        if (!ASSERT_EQ(saved_error, -EINVAL, "fail_5_error"))
                goto cleanup;
 
+       /* fail_6 - abnormal cnt */
+       opts.addrs = (const unsigned long *) addrs;
+       opts.syms = NULL;
+       opts.cnt = INT_MAX;
+       opts.cookies = NULL;
+
+       link = bpf_program__attach_kprobe_multi_opts(skel->progs.test_kprobe_manual,
+                                                    NULL, &opts);
+       saved_error = -errno;
+       if (!ASSERT_ERR_PTR(link, "fail_6"))
+               goto cleanup;
+
+       if (!ASSERT_EQ(saved_error, -E2BIG, "fail_6_error"))
+               goto cleanup;
+
 cleanup:
        bpf_link__destroy(link);
        kprobe_multi__destroy(skel);