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list: Split list_del() debug checking into separate function

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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>
This commit is contained in:
Kees Cook 2016-08-17 14:42:10 -07:00 committed by Paul E. McKenney
parent 54acd4397d
commit 0cd340dcb0
2 changed files with 32 additions and 36 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

15
include/linux/list.h
View File

@ -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

53
lib/list_debug.c
View File

@ -39,41 +39,34 @@ bool __list_add_valid(struct list_head *new, struct list_head *prev,
}
EXPORT_SYMBOL(__list_add_valid);
void __list_del_entry(struct list_head *entry)
bool __list_del_entry_valid(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;
if (unlikely(next == LIST_POISON1)) {
WARN(1, "list_del corruption, %p->next is LIST_POISON1 (%p)\n",
entry, LIST_POISON1);
return false;
}
if (unlikely(prev == LIST_POISON2)) {
WARN(1, "list_del corruption, %p->prev is LIST_POISON2 (%p)\n",
entry, LIST_POISON2);
return false;
}
if (unlikely(prev->next != entry)) {
WARN(1, "list_del corruption. prev->next should be %p, but was %p\n",
entry, prev->next);
return false;
}
if (unlikely(next->prev != entry)) {
WARN(1, "list_del corruption. next->prev should be %p, but was %p\n",
entry, next->prev);
return false;
}
return true;
__list_del(prev, next);
}
EXPORT_SYMBOL(__list_del_entry);
/**
* 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);
EXPORT_SYMBOL(__list_del_entry_valid);