selftests/bpf: Add negtive test cases for task iter

Incorporate a test case to assess the handling of invalid flags or
task__nullable parameters passed to bpf_iter_task_new(). Prior to the
preceding commit, this scenario could potentially trigger a kernel panic.
However, with the previous commit, this test case is expected to function
correctly.

Signed-off-by: Yafang Shao <laoar.shao@gmail.com>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Link: https://lore.kernel.org/bpf/20240217114152.1623-3-laoar.shao@gmail.com

diff --git a/tools/testing/selftests/bpf/prog_tests/iters.c b/tools/testing/selftests/bpf/prog_tests/iters.c
index bf84d4a..3c44037 100644 (file)
--- a/tools/testing/selftests/bpf/prog_tests/iters.c
+++ b/tools/testing/selftests/bpf/prog_tests/iters.c
@@ -193,6 +193,7 @@ static void subtest_task_iters(void)
        ASSERT_EQ(skel->bss->procs_cnt, 1, "procs_cnt");
        ASSERT_EQ(skel->bss->threads_cnt, thread_num + 1, "threads_cnt");
        ASSERT_EQ(skel->bss->proc_threads_cnt, thread_num + 1, "proc_threads_cnt");
+       ASSERT_EQ(skel->bss->invalid_cnt, 0, "invalid_cnt");
        pthread_mutex_unlock(&do_nothing_mutex);
        for (int i = 0; i < thread_num; i++)
                ASSERT_OK(pthread_join(thread_ids[i], &ret), "pthread_join");

diff --git a/tools/testing/selftests/bpf/progs/iters_task.c b/tools/testing/selftests/bpf/progs/iters_task.c
index c9b4055..e4d53e4 100644 (file)
--- a/tools/testing/selftests/bpf/progs/iters_task.c
+++ b/tools/testing/selftests/bpf/progs/iters_task.c
@@ -10,7 +10,7 @@
 char _license[] SEC("license") = "GPL";
 
 pid_t target_pid;
-int procs_cnt, threads_cnt, proc_threads_cnt;
+int procs_cnt, threads_cnt, proc_threads_cnt, invalid_cnt;
 
 void bpf_rcu_read_lock(void) __ksym;
 void bpf_rcu_read_unlock(void) __ksym;
@@ -26,6 +26,16 @@ int iter_task_for_each_sleep(void *ctx)
        procs_cnt = threads_cnt = proc_threads_cnt = 0;
 
        bpf_rcu_read_lock();
+       bpf_for_each(task, pos, NULL, ~0U) {
+               /* Below instructions shouldn't be executed for invalid flags */
+               invalid_cnt++;
+       }
+
+       bpf_for_each(task, pos, NULL, BPF_TASK_ITER_PROC_THREADS) {
+               /* Below instructions shouldn't be executed for invalid task__nullable */
+               invalid_cnt++;
+       }
+
        bpf_for_each(task, pos, NULL, BPF_TASK_ITER_ALL_PROCS)
                if (pos->pid == target_pid)
                        procs_cnt++;