1 files changed, 46 insertions, 74 deletions

diff --git a/lib/list_debug.c b/lib/list_debug.c
index c24c2f7e296f..ee7eeeb8f92c 100644
--- a/lib/list_debug.c
+++ b/lib/list_debug.c
@@ -2,8 +2,8 @@
  * 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 and error reporting for
+ * LIST_HARDENED and DEBUG_LIST.
  */
 
 #include <linux/export.h>
@@ -13,88 +13,60 @@
 #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)
+__list_valid_slowpath
+bool __list_add_valid_or_report(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;
-	prev->next = new;
+	if (CHECK_DATA_CORRUPTION(prev == NULL, NULL,
+			"list_add corruption. prev is NULL.\n") ||
+	    CHECK_DATA_CORRUPTION(next == NULL, NULL,
+			"list_add corruption. next is NULL.\n") ||
+	    CHECK_DATA_CORRUPTION(next->prev != prev, next,
+			"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, prev,
+			"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, NULL,
+			"list_add double add: new=%px, prev=%px, next=%px.\n",
+			new, prev, next))
+		return false;
+
+	return true;
 }
-EXPORT_SYMBOL(__list_add);
+EXPORT_SYMBOL(__list_add_valid_or_report);
 
-void __list_del_entry(struct list_head *entry)
+__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 (WARN(next == LIST_POISON1,
-		"list_del corruption, %p->next is LIST_POISON1 (%p)\n",
-		entry, LIST_POISON1) ||
-	    WARN(prev == LIST_POISON2,
-		"list_del corruption, %p->prev is LIST_POISON2 (%p)\n",
-		entry, LIST_POISON2) ||
-	    WARN(prev->next != entry,
-		"list_del corruption. prev->next should be %p, "
-		"but was %p\n", entry, prev->next) ||
-	    WARN(next->prev != entry,
-		"list_del corruption. next->prev should be %p, "
-		"but was %p\n", entry, next->prev))
-		return;
-
-	__list_del(prev, next);
-}
-EXPORT_SYMBOL(__list_del_entry);
+	if (CHECK_DATA_CORRUPTION(next == NULL, NULL,
+			"list_del corruption, %px->next is NULL\n", entry) ||
+	    CHECK_DATA_CORRUPTION(prev == NULL, NULL,
+			"list_del corruption, %px->prev is NULL\n", entry) ||
+	    CHECK_DATA_CORRUPTION(next == LIST_POISON1, next,
+			"list_del corruption, %px->next is LIST_POISON1 (%px)\n",
+			entry, LIST_POISON1) ||
+	    CHECK_DATA_CORRUPTION(prev == LIST_POISON2, prev,
+			"list_del corruption, %px->prev is LIST_POISON2 (%px)\n",
+			entry, LIST_POISON2) ||
+	    CHECK_DATA_CORRUPTION(prev->next != entry, prev,
+			"list_del corruption. prev->next should be %px, but was %px. (prev=%px)\n",
+			entry, prev->next, prev) ||
+	    CHECK_DATA_CORRUPTION(next->prev != entry, next,
+			"list_del corruption. next->prev should be %px, but was %px. (next=%px)\n",
+			entry, next->prev, next))
+		return false;
 
-/**
- * list_del - deletes entry from list.
- * @entry: the element to delete from the list.
- * Note: list_empty on entry does not return true after this, the entry is
- * in an undefined state.
- */
-void list_del(struct list_head *entry)
-{
-	__list_del_entry(entry);
-	entry->next = LIST_POISON1;
-	entry->prev = LIST_POISON2;
-}
-EXPORT_SYMBOL(list_del);
-
-/*
- * RCU variants.
- */
-void __list_add_rcu(struct list_head *new,
-		    struct list_head *prev, struct list_head *next)
-{
-	WARN(next->prev != prev,
-		"list_add_rcu corruption. next->prev should be prev (%p), but was %p. (next=%p).\n",
-		prev, next->prev, next);
-	WARN(prev->next != next,
-		"list_add_rcu corruption. prev->next should be next (%p), but was %p. (prev=%p).\n",
-		next, prev->next, prev);
-	new->next = next;
-	new->prev = prev;
-	rcu_assign_pointer(list_next_rcu(prev), new);
-	next->prev = new;
+	return true;
 }
-EXPORT_SYMBOL(__list_add_rcu);
+EXPORT_SYMBOL(__list_del_entry_valid_or_report);