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 
__list_add_valid(struct list_head * new,struct list_head * prev,struct list_head * next)20 bool __list_add_valid(struct list_head *new, struct list_head *prev,
21 		      struct list_head *next)
22 {
23 	if (CHECK_DATA_CORRUPTION(prev == NULL,
24 			"list_add corruption. prev is NULL.\n") ||
25 	    CHECK_DATA_CORRUPTION(next == NULL,
26 			"list_add corruption. next is NULL.\n") ||
27 	    CHECK_DATA_CORRUPTION(next->prev != prev,
28 			"list_add corruption. next->prev should be prev (%px), but was %px. (next=%px).\n",
29 			prev, next->prev, next) ||
30 	    CHECK_DATA_CORRUPTION(prev->next != next,
31 			"list_add corruption. prev->next should be next (%px), but was %px. (prev=%px).\n",
32 			next, prev->next, prev) ||
33 	    CHECK_DATA_CORRUPTION(new == prev || new == next,
34 			"list_add double add: new=%px, prev=%px, next=%px.\n",
35 			new, prev, next))
36 		return false;
37 
38 	return true;
39 }
40 EXPORT_SYMBOL(__list_add_valid);
41 
__list_del_entry_valid(struct list_head * entry)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 (CHECK_DATA_CORRUPTION(next == NULL,
50 			"list_del corruption, %px->next is NULL\n", entry) ||
51 	    CHECK_DATA_CORRUPTION(prev == NULL,
52 			"list_del corruption, %px->prev is NULL\n", entry) ||
53 	    CHECK_DATA_CORRUPTION(next == LIST_POISON1,
54 			"list_del corruption, %px->next is LIST_POISON1 (%px)\n",
55 			entry, LIST_POISON1) ||
56 	    CHECK_DATA_CORRUPTION(prev == LIST_POISON2,
57 			"list_del corruption, %px->prev is LIST_POISON2 (%px)\n",
58 			entry, LIST_POISON2) ||
59 	    CHECK_DATA_CORRUPTION(prev->next != entry,
60 			"list_del corruption. prev->next should be %px, but was %px. (prev=%px)\n",
61 			entry, prev->next, prev) ||
62 	    CHECK_DATA_CORRUPTION(next->prev != entry,
63 			"list_del corruption. next->prev should be %px, but was %px. (next=%px)\n",
64 			entry, next->prev, next))
65 		return false;
66 
67 	return true;
68 
69 }
70 EXPORT_SYMBOL(__list_del_entry_valid);
71