Slab allocators: fail if ksize is called with a NULL parameter

A NULL pointer means that the object was not allocated.  One cannot
determine the size of an object that has not been allocated.  Currently we
return 0 but we really should BUG() on attempts to determine the size of
something nonexistent.

krealloc() interprets NULL to mean a zero sized object.  Handle that
separately in krealloc().

Signed-off-by: Christoph Lameter <clameter@sgi.com>
Acked-by: Pekka Enberg <penberg@cs.helsinki.fi>
Cc: Matt Mackall <mpm@selenic.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

1 files changed, 2 insertions, 1 deletions

diff --git a/mm/slub.c b/mm/slub.c
index b7d3664fa3a9..d7c044dbd157 100644
--- a/mm/slub.c
+++ b/mm/slub.c
@@ -2449,7 +2449,8 @@ size_t ksize(const void *object)
         struct page *page;
         struct kmem_cache *s;
 
-        if (unlikely(ZERO_OR_NULL_PTR(object)))
+        BUG_ON(!object);
+        if (unlikely(object == ZERO_SIZE_PTR))
                 return 0;
 
         page = get_object_page(object);