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/slob.c b/mm/slob.c
index a886e83..de5d556 100644
--- a/mm/slob.c
+++ b/mm/slob.c
@@ -484,7 +484,8 @@ size_t ksize(const void *block)
 {
 	struct slob_page *sp;
 
-	if (unlikely(ZERO_OR_NULL_PTR(block)))
+	BUG_ON(!block);
+	if (unlikely(block == ZERO_SIZE_PTR))
 		return 0;
 
 	sp = (struct slob_page *)virt_to_page(block);