drivers/gpu/drm/i915/i915_user_extensions.c

   1 /*
   2  * SPDX-License-Identifier: MIT
   3  *
   4  * Copyright © 2018 Intel Corporation
   5  */
   6
   7 #include <linux/nospec.h>
   8 #include <linux/sched/signal.h>
   9 #include <linux/uaccess.h>
  10
  11 #include <uapi/drm/i915_drm.h>
  12
  13 #include "i915_user_extensions.h"
  14 #include "i915_utils.h"
  15
  16 int i915_user_extensions(struct i915_user_extension __user *ext,
  17                          const i915_user_extension_fn *tbl,
  18                          unsigned int count,
  19                          void *data)
  20 {
  21         unsigned int stackdepth = 512;
  22
  23         while (ext) {
  24                 int i, err;
  25                 u32 name;
  26                 u64 next;
  27
  28                 if (!stackdepth--) /* recursion vs useful flexibility */
  29                         return -E2BIG;
  30
  31                 err = check_user_mbz(&ext->flags);
  32                 if (err)
  33                         return err;
  34
  35                 for (i = 0; i < ARRAY_SIZE(ext->rsvd); i++) {
  36                         err = check_user_mbz(&ext->rsvd[i]);
  37                         if (err)
  38                                 return err;
  39                 }
  40
  41                 if (get_user(name, &ext->name))
  42                         return -EFAULT;
  43
  44                 err = -EINVAL;
  45                 if (name < count) {
  46                         name = array_index_nospec(name, count);
  47                         if (tbl[name])
  48                                 err = tbl[name](ext, data);
  49                 }
  50                 if (err)
  51                         return err;
  52
  53                 if (get_user(next, &ext->next_extension) ||
  54                     overflows_type(next, ext))
  55                         return -EFAULT;
  56
  57                 ext = u64_to_user_ptr(next);
  58         }
  59
  60         return 0;
  61 }