1 files changed, 72 insertions, 0 deletions
diff --git a/lib/list_debug.c b/lib/list_debug.c
new file mode 100644
index 0000000000..db602417fe
--- /dev/null
+++ b/lib/list_debug.c
@@ -0,0 +1,72 @@
+/*
+ * Copyright 2006, Red Hat, Inc., Dave Jones
+ * Released under the General Public License (GPL).
+ *
+ * This file contains the linked list validation and error reporting for
+ * LIST_HARDENED and DEBUG_LIST.
+ */
+
+#include <linux/export.h>
+#include <linux/list.h>
+#include <linux/bug.h>
+#include <linux/kernel.h>
+#include <linux/rculist.h>
+
+/*
+ * Check that the data structures for the list manipulations are reasonably
+ * valid. Failures here indicate memory corruption (and possibly an exploit
+ * attempt).
+ */
+
+__list_valid_slowpath
+bool __list_add_valid_or_report(struct list_head *new, struct list_head *prev,
+				struct list_head *next)
+{
+	if (CHECK_DATA_CORRUPTION(prev == NULL,
+			"list_add corruption. prev is NULL.\n") ||
+	    CHECK_DATA_CORRUPTION(next == NULL,
+			"list_add corruption. next is NULL.\n") ||
+	    CHECK_DATA_CORRUPTION(next->prev != prev,
+			"list_add corruption. next->prev should be prev (%px), but was %px. (next=%px).\n",
+			prev, next->prev, next) ||
+	    CHECK_DATA_CORRUPTION(prev->next != next,
+			"list_add corruption. prev->next should be next (%px), but was %px. (prev=%px).\n",
+			next, prev->next, prev) ||
+	    CHECK_DATA_CORRUPTION(new == prev || new == next,
+			"list_add double add: new=%px, prev=%px, next=%px.\n",
+			new, prev, next))
+		return false;
+
+	return true;
+}
+EXPORT_SYMBOL(__list_add_valid_or_report);
+
+__list_valid_slowpath
+bool __list_del_entry_valid_or_report(struct list_head *entry)
+{
+	struct list_head *prev, *next;
+
+	prev = entry->prev;
+	next = entry->next;
+
+	if (CHECK_DATA_CORRUPTION(next == NULL,
+			"list_del corruption, %px->next is NULL\n", entry) ||
+	    CHECK_DATA_CORRUPTION(prev == NULL,
+			"list_del corruption, %px->prev is NULL\n", entry) ||
+	    CHECK_DATA_CORRUPTION(next == LIST_POISON1,
+			"list_del corruption, %px->next is LIST_POISON1 (%px)\n",
+			entry, LIST_POISON1) ||
+	    CHECK_DATA_CORRUPTION(prev == LIST_POISON2,
+			"list_del corruption, %px->prev is LIST_POISON2 (%px)\n",
+			entry, LIST_POISON2) ||
+	    CHECK_DATA_CORRUPTION(prev->next != entry,
+			"list_del corruption. prev->next should be %px, but was %px. (prev=%px)\n",
+			entry, prev->next, prev) ||
+	    CHECK_DATA_CORRUPTION(next->prev != entry,
+			"list_del corruption. next->prev should be %px, but was %px. (next=%px)\n",
+			entry, next->prev, next))
+		return false;
+
+	return true;
+}
+EXPORT_SYMBOL(__list_del_entry_valid_or_report);