bpf: mark bpf_dummy_struct_ops.test_1 parameter as nullable

In the Linux kernel, the following vulnerability has been resolved: bpf: mark bpf_dummy_struct_ops.test_1 parameter as nullable Test case dummy_st_ops/dummy_init_ret_value passes NULL as the first parameter of the test_1() function. Mark this parameter as nullable to make verifier aware of such possibility. Otherwise, NULL check in the test_1() code: SEC("struct_ops/test_1") int BPF_PROG(test_1, struct bpf_dummy_ops_state *state) { if (!state) return ...; ... access state ... } Might be removed by verifier, thus triggering NULL pointer dereference under certain conditions.