[PATCH 21/23] usercopy: Restrict non-usercopy caches to size 0

From: Kees Cook
Date: Mon Jun 19 2017 - 19:43:25 EST

With all known usercopied cache whitelists now defined in the kernel, switch
the default usercopy region of kmem_cache_create() to size 0. Any new caches
with usercopy regions will now need to use kmem_cache_create_usercopy()
instead of kmem_cache_create().

This patch is modified from Brad Spengler/PaX Team's PAX_USERCOPY
whitelisting code in the last public patch of grsecurity/PaX based on my
understanding of the code. Changes or omissions from the original code are
mine and don't reflect the original grsecurity/PaX code.

Signed-off-by: Kees Cook <keescook@xxxxxxxxxxxx>
Cc: David Windsor <dave@xxxxxxxxxxxx>
mm/slab_common.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/mm/slab_common.c b/mm/slab_common.c
index 685321a0d355..2365dd21623d 100644
--- a/mm/slab_common.c
+++ b/mm/slab_common.c
@@ -512,7 +512,7 @@ struct kmem_cache *
kmem_cache_create(const char *name, size_t size, size_t align,
unsigned long flags, void (*ctor)(void *))
- return kmem_cache_create_usercopy(name, size, align, flags, 0, size,
+ return kmem_cache_create_usercopy(name, size, align, flags, 0, 0,