From: Kees Cook <keesc...@chromium.org>
Instead of using ipc_rcu_alloc() which only performs the refcount
bump, open code it. This also allows for msg_queue structure
layout to be randomized in the future.
Signed-off-by: Kees Cook <keesc...@chromium.org>
Signed-off-by: Manfred Spraul <manf...@colorfullife.com>
---
ipc/msg.c | 18 ++++++++++++++----
1 file changed, 14 insertions(+), 4 deletions(-)
diff --git a/ipc/msg.c b/ipc/msg.c
index 25d43e2..10094a7 100644
--- a/ipc/msg.c
+++ b/ipc/msg.c
@@ -109,6 +109,19 @@ static void msg_rcu_free(struct rcu_head *head)
__msg_free(msq);
}
+static struct msg_queue *msg_alloc(void)
+{
+ struct msg_queue *msq;
+
+ msq = kvmalloc(sizeof(*msq), GFP_KERNEL);
+ if (unlikely(!msq))
+ return NULL;
+
+ atomic_set(&msq->q_perm.refcount, 1);
+
+ return msq;
+}
+
/**
* newque - Create a new msg queue
* @ns: namespace
@@ -123,10 +136,7 @@ static int newque(struct ipc_namespace *ns, struct
ipc_params *params)
key_t key = params->key;
int msgflg = params->flg;
- BUILD_BUG_ON(offsetof(struct msg_queue, q_perm) != 0);
-
- msq = container_of(ipc_rcu_alloc(sizeof(*msq)), struct msg_queue,
- q_perm);
+ msq = msg_alloc();
if (!msq)
return -ENOMEM;
--
2.9.3
