lib/list_debug.c

   1 /*
   2  * Copyright 2006, Red Hat, Inc., Dave Jones
   3  * Released under the General Public License (GPL).
   4  *
   5  * This file contains the linked list validation for DEBUG_LIST.
   6  */
   7
   8 #include <linux/export.h>
   9 #include <linux/list.h>
  10 #include <linux/bug.h>
  11 #include <linux/kernel.h>
  12 #include <linux/rculist.h>
  13
  14 /*
  15  * Check that the data structures for the list manipulations are reasonably
  16  * valid. Failures here indicate memory corruption (and possibly an exploit
  17  * attempt).
  18  */
  19
  20 bool __list_add_valid(struct list_head *new, struct list_head *prev,
  21                       struct list_head *next)
  22 {
  23         if (unlikely(next->prev != prev)) {
  24                 WARN(1, "list_add corruption. next->prev should be prev (%p), but was %p. (next=%p).\n",
  25                         prev, next->prev, next);
  26                 return false;
  27         }
  28         if (unlikely(prev->next != next)) {
  29                 WARN(1, "list_add corruption. prev->next should be next (%p), but was %p. (prev=%p).\n",
  30                         next, prev->next, prev);
  31                 return false;
  32         }
  33         if (unlikely(new == prev || new == next)) {
  34                 WARN(1, "list_add double add: new=%p, prev=%p, next=%p.\n",
  35                         new, prev, next);
  36                 return false;
  37         }
  38         return true;
  39 }
  40 EXPORT_SYMBOL(__list_add_valid);
  41
  42 bool __list_del_entry_valid(struct list_head *entry)
  43 {
  44         struct list_head *prev, *next;
  45
  46         prev = entry->prev;
  47         next = entry->next;
  48
  49         if (unlikely(next == LIST_POISON1)) {
  50                 WARN(1, "list_del corruption, %p->next is LIST_POISON1 (%p)\n",
  51                         entry, LIST_POISON1);
  52                 return false;
  53         }
  54         if (unlikely(prev == LIST_POISON2)) {
  55                 WARN(1, "list_del corruption, %p->prev is LIST_POISON2 (%p)\n",
  56                         entry, LIST_POISON2);
  57                 return false;
  58         }
  59         if (unlikely(prev->next != entry)) {
  60                 WARN(1, "list_del corruption. prev->next should be %p, but was %p\n",
  61                         entry, prev->next);
  62                 return false;
  63         }
  64         if (unlikely(next->prev != entry)) {
  65                 WARN(1, "list_del corruption. next->prev should be %p, but was %p\n",
  66                         entry, next->prev);
  67                 return false;
  68         }
  69         return true;
  70
  71 }
  72 EXPORT_SYMBOL(__list_del_entry_valid);