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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: Kees Cook <keescook@chromium.org>
Signed-off-by: Manfred Spraul <manfred@colorfullife.com>
Cc: Davidlohr Bueso <dave@stgolabs.net>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
This commit is contained in:
Kees Cook 2017-07-12 14:35:07 -07:00 committed by Linus Torvalds
parent 3e0c24042e
commit 52f908904e
1 changed files with 14 additions and 4 deletions
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18
ipc/msg.c
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@ -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;