slab: introduce kzfree()

kzfree() is a wrapper for kfree() that additionally zeroes the underlying
memory before releasing it to the slab allocator.

Currently there is code which memset()s the memory region of an object
before releasing it back to the slab allocator to make sure
security-sensitive data are really zeroed out after use.

These callsites can then just use kzfree() which saves some code, makes
users greppable and allows for a stupid destructor that isn't necessarily
aware of the actual object size.

Signed-off-by: Johannes Weiner <hannes@cmpxchg.org>
Reviewed-by: Pekka Enberg <penberg@cs.helsinki.fi>
Cc: Matt Mackall <mpm@selenic.com>
Acked-by: Christoph Lameter <cl@linux-foundation.org>
Cc: Nick Piggin <npiggin@suse.de>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

1 files changed, 1 insertions, 0 deletions

diff --git a/include/linux/slab.h b/include/linux/slab.h
index f96d13c281e8..24c5602bee99 100644
--- a/include/linux/slab.h
+++ b/include/linux/slab.h
@@ -127,6 +127,7 @@ int kmem_ptr_validate(struct kmem_cache *cachep, const void *ptr);
 void * __must_check __krealloc(const void *, size_t, gfp_t);
 void * __must_check krealloc(const void *, size_t, gfp_t);
 void kfree(const void *);
+void kzfree(const void *);
 size_t ksize(const void *);
 
 /*