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

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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>
This commit is contained in:
Christoph Lameter 2007-10-16 01:24:46 -07:00 committed by Linus Torvalds
parent 0da7e01f5f
commit ef8b4520bd
4 changed files with 10 additions and 5 deletions
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3
mm/slab.c
View File

@ -4446,7 +4446,8 @@ const struct seq_operations slabstats_op = {
*/ */
size_t ksize(const void *objp) size_t ksize(const void *objp)
{ {
if (unlikely(ZERO_OR_NULL_PTR(objp))) BUG_ON(!objp);
if (unlikely(objp == ZERO_SIZE_PTR))
return 0; return 0;
return obj_size(virt_to_cache(objp)); return obj_size(virt_to_cache(objp));

3
mm/slob.c
View File

@ -484,7 +484,8 @@ size_t ksize(const void *block)
{ {
struct slob_page *sp; struct slob_page *sp;
if (unlikely(ZERO_OR_NULL_PTR(block))) BUG_ON(!block);
if (unlikely(block == ZERO_SIZE_PTR))
return 0; return 0;
sp = (struct slob_page *)virt_to_page(block); sp = (struct slob_page *)virt_to_page(block);

3
mm/slub.c
View File

@ -2449,7 +2449,8 @@ size_t ksize(const void *object)
struct page *page; struct page *page;
struct kmem_cache *s; struct kmem_cache *s;
if (unlikely(ZERO_OR_NULL_PTR(object))) BUG_ON(!object);
if (unlikely(object == ZERO_SIZE_PTR))
return 0; return 0;
page = get_object_page(object); page = get_object_page(object);

6
mm/util.c
View File

@ -81,14 +81,16 @@ EXPORT_SYMBOL(kmemdup);
void *krealloc(const void *p, size_t new_size, gfp_t flags) void *krealloc(const void *p, size_t new_size, gfp_t flags)
{ {
void *ret; void *ret;
size_t ks; size_t ks = 0;
if (unlikely(!new_size)) { if (unlikely(!new_size)) {
kfree(p); kfree(p);
return ZERO_SIZE_PTR; return ZERO_SIZE_PTR;
} }
ks = ksize(p); if (p)
ks = ksize(p);
if (ks >= new_size) if (ks >= new_size)
return (void *)p; return (void *)p;