ipc: convert ipc_namespace.count 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.

Link: http://lkml.kernel.org/r/1499417992-3238-2-git-send-email-elena.reshetova@intel.com
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>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Cc: "Eric W. Biederman" <ebiederm@xmission.com>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: Alexey Dobriyan <adobriyan@gmail.com>
Cc: Serge Hallyn <serge@hallyn.com>
Cc: <arozansk@redhat.com>
Cc: Davidlohr Bueso <dave@stgolabs.net>
Cc: Manfred Spraul <manfred@colorfullife.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

1 files changed, 1 insertions, 1 deletions

diff --git a/ipc/msgutil.c b/ipc/msgutil.c
index bf74eaa5c39f..84598025a6ad 100644
--- a/ipc/msgutil.c
+++ b/ipc/msgutil.c
@@ -29,7 +29,7 @@ DEFINE_SPINLOCK(mq_lock);
  * and not CONFIG_IPC_NS.
  */
 struct ipc_namespace init_ipc_ns = {
-        .count          = ATOMIC_INIT(1),
+        .count          = REFCOUNT_INIT(1),
         .user_ns = &init_user_ns,
         .ns.inum = PROC_IPC_INIT_INO,
 #ifdef CONFIG_IPC_NS