Skip to content

Commit

Permalink
ipc/msg: avoid ipc_rcu_alloc()
Browse files Browse the repository at this point in the history
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/[email protected]
Signed-off-by: Kees Cook <[email protected]>
Signed-off-by: Manfred Spraul <[email protected]>
Cc: Davidlohr Bueso <[email protected]>
Signed-off-by: Andrew Morton <[email protected]>
Signed-off-by: Linus Torvalds <[email protected]>
  • Loading branch information
kees authored and torvalds committed Jul 12, 2017
1 parent 3e0c240 commit 52f9089
Showing 1 changed file with 14 additions and 4 deletions.
18 changes: 14 additions & 4 deletions ipc/msg.c
Original file line number Diff line number Diff line change
Expand Up @@ -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
Expand All @@ -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;

Expand Down

0 comments on commit 52f9089

Please sign in to comment.