list: Split list_del() debug checking into separate function
Similar to the list_add() debug consolidation, this commit consolidates
the debug checking performed during CONFIG_DEBUG_LIST into a new
__list_del_entry_valid() function, and stops list updates when corruption
is found.
Refactored from same hardening in PaX and Grsecurity.
Signed-off-by: Kees Cook <keescook@chromium.org>
Acked-by: Steven Rostedt <rostedt@goodmis.org>
Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Acked-by: Rik van Riel <riel@redhat.com>
diff --git a/include/linux/list.h b/include/linux/list.h
index b6da9b1..d1039ec 100644
--- a/include/linux/list.h
+++ b/include/linux/list.h
@@ -32,6 +32,7 @@ static inline void INIT_LIST_HEAD(struct list_head *list)
extern bool __list_add_valid(struct list_head *new,
struct list_head *prev,
struct list_head *next);
+extern bool __list_del_entry_valid(struct list_head *entry);
#else
static inline bool __list_add_valid(struct list_head *new,
struct list_head *prev,
@@ -39,6 +40,10 @@ static inline bool __list_add_valid(struct list_head *new,
{
return true;
}
+static inline bool __list_del_entry_valid(struct list_head *entry)
+{
+ return true;
+}
#endif
/*
@@ -106,22 +111,20 @@ static inline void __list_del(struct list_head * prev, struct list_head * next)
* Note: list_empty() on entry does not return true after this, the entry is
* in an undefined state.
*/
-#ifndef CONFIG_DEBUG_LIST
static inline void __list_del_entry(struct list_head *entry)
{
+ if (!__list_del_entry_valid(entry))
+ return;
+
__list_del(entry->prev, entry->next);
}
static inline void list_del(struct list_head *entry)
{
- __list_del(entry->prev, entry->next);
+ __list_del_entry(entry);
entry->next = LIST_POISON1;
entry->prev = LIST_POISON2;
}
-#else
-extern void __list_del_entry(struct list_head *entry);
-extern void list_del(struct list_head *entry);
-#endif
/**
* list_replace - replace old entry by new one