libceph: convert ceph_snap_context.nref from atomic_t to refcount_t

refcount_t type and corresponding API should be
used instead of atomic_t when the variable is used as
a reference counter. This allows to avoid accidental
refcounter overflows that might lead to use-after-free
situations.

Signed-off-by: Elena Reshetova <elena.reshetova@intel.com>
Signed-off-by: Hans Liljestrand <ishkamiel@gmail.com>
Signed-off-by: Kees Cook <keescook@chromium.org>
Signed-off-by: David Windsor <dwindsor@gmail.com>
Signed-off-by: Ilya Dryomov <idryomov@gmail.com>

1 files changed, 2 insertions, 1 deletions

diff --git a/include/linux/ceph/libceph.h b/include/linux/ceph/libceph.h
index cecbf5a26e5a..3229ae6c7846 100644
--- a/include/linux/ceph/libceph.h
+++ b/include/linux/ceph/libceph.h
@@ -14,6 +14,7 @@
 #include <linux/wait.h>
 #include <linux/writeback.h>
 #include <linux/slab.h>
+#include <linux/refcount.h>
 
 #include <linux/ceph/types.h>
 #include <linux/ceph/messenger.h>
@@ -161,7 +162,7 @@ struct ceph_client {
  * dirtied.
  */
 struct ceph_snap_context {
-        atomic_t nref;
+        refcount_t nref;
         u64 seq;
         u32 num_snaps;
         u64 snaps[];