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 and error reporting for
 6 * LIST_HARDENED and DEBUG_LIST.
 7 */
 8
 9#include <linux/export.h>
10#include <linux/list.h>
11#include <linux/bug.h>
12#include <linux/kernel.h>
13#include <linux/rculist.h>
14
15/*
16 * Check that the data structures for the list manipulations are reasonably
17 * valid. Failures here indicate memory corruption (and possibly an exploit
18 * attempt).
19 */
20
21__list_valid_slowpath
22bool __list_add_valid_or_report(struct list_head *new, struct list_head *prev,
23				struct list_head *next)
24{
25	if (CHECK_DATA_CORRUPTION(prev == NULL, NULL,
26			"list_add corruption. prev is NULL.\n") ||
27	    CHECK_DATA_CORRUPTION(next == NULL, NULL,
28			"list_add corruption. next is NULL.\n") ||
29	    CHECK_DATA_CORRUPTION(next->prev != prev, next,
30			"list_add corruption. next->prev should be prev (%px), but was %px. (next=%px).\n",
31			prev, next->prev, next) ||
32	    CHECK_DATA_CORRUPTION(prev->next != next, prev,
33			"list_add corruption. prev->next should be next (%px), but was %px. (prev=%px).\n",
34			next, prev->next, prev) ||
35	    CHECK_DATA_CORRUPTION(new == prev || new == next, NULL,
36			"list_add double add: new=%px, prev=%px, next=%px.\n",
37			new, prev, next))
38		return false;
39
40	return true;
41}
42EXPORT_SYMBOL(__list_add_valid_or_report);
43
44__list_valid_slowpath
45bool __list_del_entry_valid_or_report(struct list_head *entry)
46{
47	struct list_head *prev, *next;
48
49	prev = entry->prev;
50	next = entry->next;
51
52	if (CHECK_DATA_CORRUPTION(next == NULL, NULL,
53			"list_del corruption, %px->next is NULL\n", entry) ||
54	    CHECK_DATA_CORRUPTION(prev == NULL, NULL,
55			"list_del corruption, %px->prev is NULL\n", entry) ||
56	    CHECK_DATA_CORRUPTION(next == LIST_POISON1, next,
57			"list_del corruption, %px->next is LIST_POISON1 (%px)\n",
58			entry, LIST_POISON1) ||
59	    CHECK_DATA_CORRUPTION(prev == LIST_POISON2, prev,
60			"list_del corruption, %px->prev is LIST_POISON2 (%px)\n",
61			entry, LIST_POISON2) ||
62	    CHECK_DATA_CORRUPTION(prev->next != entry, prev,
63			"list_del corruption. prev->next should be %px, but was %px. (prev=%px)\n",
64			entry, prev->next, prev) ||
65	    CHECK_DATA_CORRUPTION(next->prev != entry, next,
66			"list_del corruption. next->prev should be %px, but was %px. (next=%px)\n",
67			entry, next->prev, next))
68		return false;
69
70	return true;
71}
72EXPORT_SYMBOL(__list_del_entry_valid_or_report);