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-rw-r--r--lib/list_debug.c48
1 files changed, 23 insertions, 25 deletions
diff --git a/lib/list_debug.c b/lib/list_debug.c
index 3859bf63561c..149dd57b583b 100644
--- a/lib/list_debug.c
+++ b/lib/list_debug.c
@@ -2,8 +2,7 @@
* Copyright 2006, Red Hat, Inc., Dave Jones
* Released under the General Public License (GPL).
*
- * This file contains the linked list implementations for
- * DEBUG_LIST.
+ * This file contains the linked list validation for DEBUG_LIST.
*/
#include <linux/export.h>
@@ -13,33 +12,32 @@
#include <linux/rculist.h>
/*
- * Insert a new entry between two known consecutive entries.
- *
- * This is only for internal list manipulation where we know
- * the prev/next entries already!
+ * Check that the data structures for the list manipulations are reasonably
+ * valid. Failures here indicate memory corruption (and possibly an exploit
+ * attempt).
*/
-void __list_add(struct list_head *new,
- struct list_head *prev,
- struct list_head *next)
+bool __list_add_valid(struct list_head *new, struct list_head *prev,
+ struct list_head *next)
{
- WARN(next->prev != prev,
- "list_add corruption. next->prev should be "
- "prev (%p), but was %p. (next=%p).\n",
- prev, next->prev, next);
- WARN(prev->next != next,
- "list_add corruption. prev->next should be "
- "next (%p), but was %p. (prev=%p).\n",
- next, prev->next, prev);
- WARN(new == prev || new == next,
- "list_add double add: new=%p, prev=%p, next=%p.\n",
- new, prev, next);
- next->prev = new;
- new->next = next;
- new->prev = prev;
- WRITE_ONCE(prev->next, new);
+ if (unlikely(next->prev != prev)) {
+ WARN(1, "list_add corruption. next->prev should be prev (%p), but was %p. (next=%p).\n",
+ prev, next->prev, next);
+ return false;
+ }
+ if (unlikely(prev->next != next)) {
+ WARN(1, "list_add corruption. prev->next should be next (%p), but was %p. (prev=%p).\n",
+ next, prev->next, prev);
+ return false;
+ }
+ if (unlikely(new == prev || new == next)) {
+ WARN(1, "list_add double add: new=%p, prev=%p, next=%p.\n",
+ new, prev, next);
+ return false;
+ }
+ return true;
}
-EXPORT_SYMBOL(__list_add);
+EXPORT_SYMBOL(__list_add_valid);
void __list_del_entry(struct list_head *entry)
{