From: Manfred Spraul <manfred@xxxxxxxxxxxxxxxx> Subject: ipc/msg.c: avoid ipc_rcu_putref for failed ipc_addid() Loosely based on a patch from Kees Cook <keescook@xxxxxxxxxxxx>: - 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@xxxxxxxxxxxxxxxx Signed-off-by: Manfred Spraul <manfred@xxxxxxxxxxxxxxxx> Cc: Kees Cook <keescook@xxxxxxxxxxxx> Cc: Davidlohr Bueso <dave@xxxxxxxxxxxx> Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx> --- ipc/msg.c | 10 +++++----- 1 file changed, 5 insertions(+), 5 deletions(-) diff -puN ipc/msg.c~ipc-msgc-avoid-ipc_rcu_putref-for-failed-ipc_addid ipc/msg.c --- a/ipc/msg.c~ipc-msgc-avoid-ipc_rcu_putref-for-failed-ipc_addid +++ a/ipc/msg.c @@ -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 * 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); _ -- To unsubscribe from this list: send the line "unsubscribe mm-commits" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
