From 19da3dd157f8db6fe727ff268dab4791d55a6371 Mon Sep 17 00:00:00 2001 From: David Rientjes Date: Mon, 21 Sep 2009 17:04:31 -0700 Subject: flex_array: poison free elements Newly initialized flex_array's and/or flex_array_part's are now poisoned with a new poison value, FLEX_ARRAY_FREE. It's value is similar to POISON_FREE used in the various slab allocators, but is different to distinguish between flex array's poisoned kmem and slab allocator poisoned kmem. This will allow us to identify flex_array_part's that only contain free elements (and free them with an addition to the flex_array API). This could also be extended in the future to identify `get' uses on elements that have not been `put'. If __GFP_ZERO is passed for a part's gfp mask, the poisoning is avoided. These elements are considered to be in-use since they have been initialized. Signed-off-by: David Rientjes Cc: Dave Hansen Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- include/linux/poison.h | 3 +++ 1 file changed, 3 insertions(+) (limited to 'include') diff --git a/include/linux/poison.h b/include/linux/poison.h index 6729f7dcd60..7fc194aef8c 100644 --- a/include/linux/poison.h +++ b/include/linux/poison.h @@ -65,6 +65,9 @@ #define MUTEX_DEBUG_INIT 0x11 #define MUTEX_DEBUG_FREE 0x22 +/********** lib/flex_array.c **********/ +#define FLEX_ARRAY_FREE 0x6c /* for use-after-free poisoning */ + /********** security/ **********/ #define KEY_DESTROY 0xbd -- cgit v1.2.3