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ipc/msg.c: avoid ipc_rcu_putref for failed ipc_addid() 

Loosely based on a patch from Kees Cook <keescook@chromium.org>:
 - id and retval can be merged
 - if ipc_addid() fails, then use call_rcu() directly.

The difference is that call_rcu is used for failed ipc_addid() calls, to
continue to guaranteed an rcu delay for security_msg_queue_free().

Link: http://lkml.kernel.org/r/20170525185107.12869-16-manfred@colorfullife.com
Signed-off-by: Manfred Spraul <manfred@colorfullife.com>
Cc: Kees Cook <keescook@chromium.org>
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:
Manfred Spraul 2017-07-12 14:35:19 -07:00 committed by Linus Torvalds
parent a2642f8770
commit 51c23b7b7d
1 changed files with 5 additions and 5 deletions
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10
ipc/msg.c
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@ -132,7 +132,7 @@ static struct msg_queue *msg_alloc(void)
static int newque(struct ipc_namespace *ns, struct ipc_params *params)
{
struct msg_queue *msq;
int id, retval;
int retval;
key_t key = params->key;
int msgflg = params->flg;
@ -160,10 +160,10 @@ static int newque(struct ipc_namespace *ns, struct ipc_params *params)
INIT_LIST_HEAD(&msq->q_senders);
/* ipc_addid() locks msq upon success. */
id = ipc_addid(&msg_ids(ns), &msq->q_perm, ns->msg_ctlmni);
if (id < 0) {
ipc_rcu_putref(&msq->q_perm, msg_rcu_free);
return id;
retval = ipc_addid(&msg_ids(ns), &msq->q_perm, ns->msg_ctlmni);
if (retval < 0) {
call_rcu(&msq->q_perm.rcu, msg_rcu_free);
return retval;
}
ipc_unlock_object(&msq->q_perm);