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Commit 52f90890 authored by Kees Cook's avatar Kees Cook Committed by Linus Torvalds
Browse files

ipc/msg: avoid ipc_rcu_alloc() 

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.

Link: http://lkml.kernel.org/r/20170525185107.12869-12-manfred@colorfullife.com


Signed-off-by: default avatarKees Cook <keescook@chromium.org>
Signed-off-by: default avatarManfred Spraul <manfred@colorfullife.com>
Cc: Davidlohr Bueso <dave@stgolabs.net>
Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
parent 3e0c2404

ipc/msg.c

+14 −4
Original line number Diff line number Diff line
@@ -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;