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 void __list_del_entry(struct list_head *entry) 43 { 44 struct list_head *prev, *next; 45 46 prev = entry->prev; 47 next = entry->next; 48 49 if (WARN(next == LIST_POISON1, 50 "list_del corruption, %p->next is LIST_POISON1 (%p)\n", 51 entry, LIST_POISON1) || 52 WARN(prev == LIST_POISON2, 53 "list_del corruption, %p->prev is LIST_POISON2 (%p)\n", 54 entry, LIST_POISON2) || 55 WARN(prev->next != entry, 56 "list_del corruption. prev->next should be %p, " 57 "but was %p\n", entry, prev->next) || 58 WARN(next->prev != entry, 59 "list_del corruption. next->prev should be %p, " 60 "but was %p\n", entry, next->prev)) 61 return; 62 63 __list_del(prev, next); 64 } 65 EXPORT_SYMBOL(__list_del_entry); 66 67 /** 68 * list_del - deletes entry from list. 69 * @entry: the element to delete from the list. 70 * Note: list_empty on entry does not return true after this, the entry is 71 * in an undefined state. 72 */ 73 void list_del(struct list_head *entry) 74 { 75 __list_del_entry(entry); 76 entry->next = LIST_POISON1; 77 entry->prev = LIST_POISON2; 78 } 79 EXPORT_SYMBOL(list_del); 80