/*
 * SPDX-License-Identifier: MIT
 *
 * Copyright © 2018 Intel Corporation
 */

#include <linux/nospec.h>
#include <linux/sched/signal.h>
#include <linux/uaccess.h>

#include <uapi/drm/i915_drm.h>

#include "i915_user_extensions.h"
#include "i915_utils.h"

int i915_user_extensions(struct i915_user_extension __user *ext,
                         const i915_user_extension_fn *tbl,
                         unsigned int count,
                         void *data)
{
        unsigned int stackdepth = 512;

        while (ext) {
                int i, err;
                u32 name;
                u64 next;

                if (!stackdepth--) /* recursion vs useful flexibility */
                        return -E2BIG;

                err = check_user_mbz(&ext->flags);
                if (err)
                        return err;

                for (i = 0; i < ARRAY_SIZE(ext->rsvd); i++) {
                        err = check_user_mbz(&ext->rsvd[i]);
                        if (err)
                                return err;
                }

                if (get_user(name, &ext->name))
                        return -EFAULT;

                err = -EINVAL;
                if (name < count) {
                        name = array_index_nospec(name, count);
                        if (tbl[name])
                                err = tbl[name](ext, data);
                }
                if (err)
                        return err;

                if (get_user(next, &ext->next_extension) ||
                    overflows_type(next, uintptr_t))
                        return -EFAULT;

                ext = u64_to_user_ptr(next);
        }

        return 0;
}