lib/list_debug.c

/*
 * Copyright 2006, Red Hat, Inc., Dave Jones
 * Released under the General Public License (GPL).
 *
 * This file contains the linked list validation for DEBUG_LIST.
 */

#include <linux/export.h>
#include <linux/list.h>
#include <linux/bug.h>
#include <linux/kernel.h>
#include <linux/rculist.h>
#include <linux/bug.h>

/*
 * Check that the data structures for the list manipulations are reasonably
 * valid. Failures here indicate memory corruption (and possibly an exploit
 * attempt).
 */

bool __list_add_valid(struct list_head *new, struct list_head *prev,
		      struct list_head *next)
{

	if (CHECK_DATA_CORRUPTION(next->prev != prev,
                        "list_add corruption. next->prev should be prev (%p), but was %p. (next=%p).\n",
                        prev, next->prev, next) ||
            CHECK_DATA_CORRUPTION(prev->next != next,
                        "list_add corruption. prev->next should be next (%p), but was %p. (prev=%p).\n",
                        next, prev->next, prev) ||
            CHECK_DATA_CORRUPTION(new == prev || new == next,
                        "list_add double add: new=%p, prev=%p, next=%p.\n",
                        new, prev, next))
                return false;

	next->prev = new;
	new->next = next;
	new->prev = prev;
	WRITE_ONCE(prev->next, new);

	return true;
}
EXPORT_SYMBOL(__list_add_valid);

bool __list_del_entry_valid(struct list_head *entry)
{
	struct list_head *prev, *next;

	prev = entry->prev;
	next = entry->next;

	if (CHECK_DATA_CORRUPTION(next == LIST_POISON1,
			"list_del corruption, %p->next is LIST_POISON1 (%p)\n",
			entry, LIST_POISON1) ||
	    CHECK_DATA_CORRUPTION(prev == LIST_POISON2,
			"list_del corruption, %p->prev is LIST_POISON2 (%p)\n",
			entry, LIST_POISON2) ||
	    CHECK_DATA_CORRUPTION(prev->next != entry,
			"list_del corruption. prev->next should be %p, but was %p\n",
			entry, prev->next) ||
	    CHECK_DATA_CORRUPTION(next->prev != entry,
			"list_del corruption. next->prev should be %p, but was %p\n",
			entry, next->prev))
		return false;

	return true;

}
EXPORT_SYMBOL(__list_del_entry_valid);