Commit 51c23b7b authored by Manfred Spraul's avatar Manfred Spraul Committed by Linus Torvalds

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.comSigned-off-by: default avatarManfred Spraul <manfred@colorfullife.com>
Cc: Kees Cook <keescook@chromium.org>
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 a2642f87
...@@ -132,7 +132,7 @@ static struct msg_queue *msg_alloc(void) ...@@ -132,7 +132,7 @@ static struct msg_queue *msg_alloc(void)
static int newque(struct ipc_namespace *ns, struct ipc_params *params) static int newque(struct ipc_namespace *ns, struct ipc_params *params)
{ {
struct msg_queue *msq; struct msg_queue *msq;
int id, retval; int retval;
key_t key = params->key; key_t key = params->key;
int msgflg = params->flg; int msgflg = params->flg;
...@@ -160,10 +160,10 @@ static int newque(struct ipc_namespace *ns, struct ipc_params *params) ...@@ -160,10 +160,10 @@ static int newque(struct ipc_namespace *ns, struct ipc_params *params)
INIT_LIST_HEAD(&msq->q_senders); INIT_LIST_HEAD(&msq->q_senders);
/* ipc_addid() locks msq upon success. */ /* ipc_addid() locks msq upon success. */
id = ipc_addid(&msg_ids(ns), &msq->q_perm, ns->msg_ctlmni); retval = ipc_addid(&msg_ids(ns), &msq->q_perm, ns->msg_ctlmni);
if (id < 0) { if (retval < 0) {
ipc_rcu_putref(&msq->q_perm, msg_rcu_free); call_rcu(&msq->q_perm.rcu, msg_rcu_free);
return id; return retval;
} }
ipc_unlock_object(&msq->q_perm); ipc_unlock_object(&msq->q_perm);
......
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