// SPDX-License-Identifier: GPL-2.0
/* Copyright (c) 2026 Qi Tang */

#include <vmlinux.h>
#include <bpf/bpf_helpers.h>
#include "bpf_misc.h"

char _license[] SEC("license") = "GPL";

/* Verify that the verifier rejects direct access to nullable PTR_TO_BUF. */
SEC("iter/bpf_map_elem")
__failure __msg("invalid mem access")
int iter_buf_null_deref(struct bpf_iter__bpf_map_elem *ctx)
{
        /*
         * ctx->key is PTR_TO_BUF | PTR_MAYBE_NULL | MEM_RDONLY.
         * Direct access without null check must be rejected.
         */
        volatile __u32 v = *(__u32 *)ctx->key;

        (void)v;
        return 0;
}

/* Verify that access after a null check is still accepted. */
SEC("iter/bpf_map_elem")
__success
int iter_buf_null_check_ok(struct bpf_iter__bpf_map_elem *ctx)
{
        __u32 *key = ctx->key;

        if (!key)
                return 0;

        volatile __u32 v = *key;

        (void)v;
        return 0;
}