xref: /openbmc/linux/lib/list_debug.c (revision a6978d1b7bb8f3a25305e8ff7d367f7289614c5d)
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
22  bool __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,
26  			"list_add corruption. prev is NULL.\n") ||
27  	    CHECK_DATA_CORRUPTION(next == NULL,
28  			"list_add corruption. next is NULL.\n") ||
29  	    CHECK_DATA_CORRUPTION(next->prev != prev,
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,
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,
36  			"list_add double add: new=%px, prev=%px, next=%px.\n",
37  			new, prev, next))
38  		return false;
39  
40  	return true;
41  }
42  EXPORT_SYMBOL(__list_add_valid_or_report);
43  
44  __list_valid_slowpath
45  bool __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,
53  			"list_del corruption, %px->next is NULL\n", entry) ||
54  	    CHECK_DATA_CORRUPTION(prev == NULL,
55  			"list_del corruption, %px->prev is NULL\n", entry) ||
56  	    CHECK_DATA_CORRUPTION(next == LIST_POISON1,
57  			"list_del corruption, %px->next is LIST_POISON1 (%px)\n",
58  			entry, LIST_POISON1) ||
59  	    CHECK_DATA_CORRUPTION(prev == LIST_POISON2,
60  			"list_del corruption, %px->prev is LIST_POISON2 (%px)\n",
61  			entry, LIST_POISON2) ||
62  	    CHECK_DATA_CORRUPTION(prev->next != entry,
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,
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  }
72  EXPORT_SYMBOL(__list_del_entry_valid_or_report);
73