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From: Hou Tao <houtao@huaweicloud.com>
To: bpf@vger.kernel.org
Cc: Martin KaFai Lau <martin.lau@linux.dev>,
	Alexei Starovoitov <alexei.starovoitov@gmail.com>,
	Andrii Nakryiko <andrii@kernel.org>,
	Song Liu <song@kernel.org>,
	Hao Luo <haoluo@google.com>,
	Yonghong Song <yonghong.song@linux.dev>,
	Daniel Borkmann <daniel@iogearbox.net>,
	KP Singh <kpsingh@kernel.org>,
	Stanislav Fomichev <sdf@google.com>,
	Jiri Olsa <jolsa@kernel.org>,
	John Fastabend <john.fastabend@gmail.com>,
	xingwei lee <xrivendell7@gmail.com>,
	houtao1@huawei.com
Subject: [PATCH bpf-next 3/4] selftests/bpf: Add test for abnormal cnt during multi-kprobe attachment
Date: Mon, 11 Dec 2023 19:28:42 +0800
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From: Hou Tao <houtao1@huawei.com>

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>
---
 .../selftests/bpf/prog_tests/kprobe_multi_test.c   | 14 ++++++++++++++
 1 file changed, 14 insertions(+)

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 4041cfa670eb..a340b6047657 100644
--- a/tools/testing/selftests/bpf/prog_tests/kprobe_multi_test.c
+++ b/tools/testing/selftests/bpf/prog_tests/kprobe_multi_test.c
@@ -300,6 +300,20 @@ static void test_attach_api_fails(void)
 	if (!ASSERT_EQ(libbpf_get_error(link), -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);
+	if (!ASSERT_ERR_PTR(link, "fail_6"))
+		goto cleanup;
+
+	if (!ASSERT_EQ(libbpf_get_error(link), -ENOMEM, "fail_6_error"))
+		goto cleanup;
+
 cleanup:
 	bpf_link__destroy(link);
 	kprobe_multi__destroy(skel);
-- 
2.29.2